Datasheets | Clocks and Timing Circuits | Timekeeper | Timekeepers

5.0 V PC real-time clock

Datasheet

Format: (311 kb)

Last Updated: 08/12/2008

Pages: 36

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M48T86
5.0 V PC real-time clock
Not For New Design

Features

Drop-in replacement for PC computer clock/calendar Counts seconds, minutes, hours, days, day of the week, date, month, and year with leap year compensation Clock accuracy better than 1 minute per month Interfaced with software as 128 RAM locations: 14 bytes of clock and control registers 114 bytes of general purpose RAM Selectable bus timing (Intel/Motorola) Three interrupts are separately softwaremaskable and testable Time-of-day alarm (once/second to once/day) Periodic rates from 122 s to 500 ms End-of-clock update cycle Programmable square wave output 10 years of data retention and clock operation in the absence of power Self-contained battery and crystal in the CAPHATTM DIP package Packaging includes a 28-lead SOIC and SNAPHAT top (to be ordered separately) SOIC package provides direct connection for a SNAPHAT top contains the battery and crystal Pin and function compatible with bq3285/7A and DS12887 RoHS compliant Lead-free second level interconnect

24 1

PCDIP24 (PC) Battery/Crystal CAPHAT

SNAPHAT (SH) Battery/Crystal

28 1

SOH28 (MH)

December 2008

Rev 7

1/36
www.st.com 1

This is information on a product still in production but not recommended for new designs.

Contents

M48T86

Contents
1 2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Signal description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 VCC, VSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 SQW (square wave output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 AD0-AD7 (multiplexed bidirectional address/data bus) . . . . . . . . . . . . . . 9 AS (address strobe input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 MOT (mode select) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 DS (data strobe input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 E (chip enable input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 IRQ (interrupt request output) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 RST (reset input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 RCL (RAM clear) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 R/W (read/write input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Non-volatile RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3

Clock operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 Address map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Time, calendar, and alarm locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Periodic interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Alarm interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Update cycle interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Oscillator control bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Update cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Square wave output selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Register A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.10.1 3.10.2 3.10.3 UIP update in progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 OSC0, OSC1, OSC2 oscillator control . . . . . . . . . . . . . . . . . . . . . . . . . 19 RS3, RS2, RS1, RS0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.11

Register B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.11.1 SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2/36

M48T86 3.11.2 3.11.3 3.11.4 3.11.5 3.11.6 3.11.7 3.11.8

Contents PIE: periodic interrupt enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 AIE: alarm interrupt enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 UIE: update ended interrupt enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 SQWE: square wave enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 DM: data mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 24/12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 DSE: daylight savings enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.12

Register C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.12.1 3.12.2 3.12.3 3.12.4 3.12.5 IRQF: interrupt request flag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 PF: periodic interrupt flag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 AF: alarm flag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 UF: update ended interrupt flag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 BIT 0 through 3: unused bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.13

Register D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.13.1 3.13.2 VRT: valid RAM and time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 BIT 0 through 6: unused bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.14

VCC noise and negative going transients . . . . . . . . . . . . . . . . . . . . . . . . . 23

4 5 6 7 8 9

Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Environmental information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

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List of tables

M48T86

List of tables
Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. Table 17. Table 18. Table 19. Table 20. Table 21. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Time, calendar, and alarm formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Square wave frequency/periodic interrupt rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Register A MSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Register B MSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Register C MSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Register D MSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Operating and AC measurement conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 DC characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Power down/up mode AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Power down/up trip points DC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 PCDIP24 24-pin plastic DIP, battery CAPHATTM, package mechanical data . . . . . . . . . 29 SOH28 28-lead plastic small outline, 4-socket battery SNAPHAT, package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 SH 4-pin SNAPHAT housing for 48 mAh battery and crystal, package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 SH 4-pin SNAPHAT housing for 120 mAh battery and crystal, package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 SNAPHAT battery table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4/36

M48T86

List of figures

List of figures
Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 24-pin DIP connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 28-pin SOIC connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Intel bus read AC waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Intel bus write mode AC waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Motorola bus read/write mode AC waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Address map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Update period timing and UIP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Update-ended/periodic interrupt relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Supply voltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 AC testing load circuit (no IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 AC testing load circuit (with IRQ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Power down/up mode AC waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 PCDIP24 24-pin plastic DIP, battery CAPHATTM, package outline . . . . . . . . . . . . . . . . . 29 SOH28 28-lead plastic small outline, 4-socket SNAPHAT, package outline . . . . . . . . . 30 SH 4-pin SNAPHAT housing for 48 mAh battery and crystal, package outline . . . . . . . 31 SH 4-pin SNAPHAT housing for 120 mAh battery and crystal, package outline . . . . . . 32 Recycling symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5/36

Description

M48T86

1

Description
The M48T86 is an industry standard real-time clock (RTC). The M48T86 is composed of a lithium energy source, quartz crystal, write protection circuitry, and a 128-byte RAM array. This provides the user with a complete subsystem packaged in either a 24-pin DIP CAPHATTM or 28-pin SNAPHAT SOIC. Functions available to the user include a nonvolatile time-of-day clock, alarm interrupts, a one-hundred-year clock with programmable interrupts, square wave output, and 128 bytes of non-volatile static RAM. The 24-pin, 600 mil DIP CAPHAT houses the M48T86 silicon with a quartz crystal and a long-life lithium button cell in a single package. The 28-pin, 330 mil SOIC provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing containing the battery and crystal. The unique design allows the SNAPHAT battery package to be mounted on top of the SOIC package after the completion of the surface mount process. Inser tion of the SNAPHAT housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device surface-mounting. The SNAPHAT housing is keyed to prevent reverse insertion. The SOIC and battery packages are shipped separately in plastic anti-static tubes or in tape & reel form. For the 28-lead SOIC, the battery/crystal package part number is "M4T28-BR12SH" (see Table 20 on page 33). Figure 1. Logic diagram
VCC

8 AD0-AD7 E R/W DS AS RST RCL MOT M48T86 SQW IRQ

VSS
AI01640

6/36

M48T86 Table 1. Signal names
Multiplexed address/data bus Chip enable input WRITE enable input Data strobe input Address strobe input Reset Input RAM clear input Bus type select input Square wave output Interrupt request output (open drain) Supply voltage Ground Not connected internally

Description

AD0-AD7 E R/W DS AS RST RCL MOT SQW IRQ VCC VSS NC

Figure 2.

24-pin DIP connections
MOT NC NC AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 VSS 1 2 3 4 5 6 M48T86 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 VCC SQW NC RCL NC IRQ RST DS NC R/W AS E

AI01641

7/36

Description Figure 3. 28-pin SOIC connections
NC MOT NC NC AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 VSS VSS 1 2 3 4 5 6 7 M48T86 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 NC VCC SQW NC RCL NC IRQ RST DS NC R/W AS E NC

M48T86

AI01642

Figure 4.

Block diagram

OSCILLATOR

/8

/ 64

/ 64

E VCC VBAT

POWER SWITCH AND WRITE PROTECT

VCC POK

PERIODIC INTERRUPT/SQUARE WAVE SELECTOR

SQUARE WAVE OUTPUT

SQW

IRQ RST

REGISTERS A,B,C,D

CLOCK/ CALENDAR UPDATE

CLOCK CALENDAR, AND ALARM RAM

DOUBLE BUFFERED

DS R/W AS BUS INTERFACE BCD/BINARY INCREMENT STORAGE REGISTERS (114 BYTES) RCL

AD0-AD7

AI01643

8/36

M48T86

Operation

2

Operation
The M48T86 clock is driven by a quartz-controlled oscillator with a nominal frequency of 32,768 Hz. The devices are tested not to exceed 23 ppm (parts per million) oscillator frequency error at 25C, which equates to approximately 1 minute per month. Automatic deselection of the device ensures the data integrity is not compromised should VCC fall below specified power-fail deselect voltage (VPFD) levels (see Figure 14 on page 27). The automatic deselection of the device remains in effect upon power up for a period of 200ms (max) after VCC rises above VPFD, provided that the real-time clock is running and the countdown chain is not reset. This allows sufficient time for VCC to stabilize and gives the system clock a wake-up period so that a valid system reset can be established. The block diagram in Figure 4 on page 8 shows the pin connections and the major internal functions of the M48T86.

2.1
2.1.1

Signal description
VCC, VSS
DC power is provided to the device on these pins.The M48T86 uses a 5 V VCC.

2.1.2

SQW (square wave output)
During normal operation (e.g., valid VCC), the SQW pin can output a signal from one of 13 taps. The frequency of the SQW pin can be changed by programming Register A as shown in Table 4 on page 18. The SQW signal can be turned on and off using the SQWE bit (Register B; Bit 3). The SQW signal is not available when VCC is less than VPFD.

2.1.3

AD0-AD7 (multiplexed bidirectional address/data bus)
The M48T86 provides a multiplexed bus in which address and data information share the same signal path. The bus cycle consists of two stages; first the address is latched, followed by the data. Address/Data multiplexing does not slow the access time of the M48T86, because the bus change from address to data occurs during the internal RAM access time. Addresses must be valid prior to the falling edge of AS (see Figure 5 on page 11), at which time the M48T86 latches the address present on AD0-AD7. Valid WRITE data must be present and held stable during the latter portion of the R/W pulse (see Figure 6 on page 11). In a READ cycle, the M48T86 outputs 8 bits of data during the latter portion of the DS pulse. The READ cycle is terminated and the bus returns to a high impedance state upon a high transition on R/W.

2.1.4

AS (address strobe input)
A positive going pulse on the Address Strobe (AS) input serves to demultiplex the bus. The falling edge of AS causes the address present on AD0-AD7 to be latched within the M48T86.

9/36

Operation

M48T86

2.1.5

MOT (mode select)
The MOT pin offers the flexibility to choose between two bus types (see Figure 7 on page 12). When connected to VCC, Motorola bus timing is selected. When connected to VSS or left disconnected, Intel bus timing is selected. The pin has an internal pull-down resistance of approximately 20 K.

2.1.6

DS (data strobe input)
The DS pin is also referred to as READ (RD). A falling edge transition on the Data Strobe (DS) input enables the output during a a READ cycle. This is very similar to an Output Enable (G) signal on other memory devices.

2.1.7

E (chip enable input)
The chip enable pin must be asserted low for a bus cycle in the M48T86 to be accessed. Bus cycles which take place without asserting E will latch the addresses present, but no data access will occur.

2.1.8

IRQ (interrupt request output)
The IRQ pin is an open drain output that can be used as an interrupt input to a processor. The IRQ output remains low as long as the status bit causing the interrupt is present and the corresponding interrupt-enable bit is set. IRQ returns to a high impedance state whenever Register C is read. The RST pin can also be used to clear pending interrupts. The IRQ bus is an open drain output so it requires an external pull-up resistor to VCC.

2.1.9

RST (reset input)
The M48T86 is reset when the RST input is pulled low. With a valid VCC applied and a low on RST, the following events occur: 1. 2. 3. 4. 5. 6. 7. 8. 9. Periodic Interrupt Enable (PIE) bit is cleared to a zero (Register B; Bit 6); Alarm Interrupt Enable (AIE) bit is cleared to a zero (Register B; Bit 5); Update Ended Interrupt Request (UF) bit is cleared to a zero (Register C; Bit 4); Interrupt Request (IRQF) bit is cleared to a zero (Register C Bit 7); Periodic Interrupt Flag (PF) bit is cleared to a zero (Register C; Bit 6); The device is not accessible until RST is returned high; Alarm Interrupt Flag (AF) bit is cleared to a zero (Register C; Bit 5); The IRQ pin is in the high impedance state Square Wave Output Enable (SQWE) bit is cleared to zero (Register B; Bit 3); and

10. Update Ended Interrupt Enable (UIE) is cleared to a zero (Register B; Bit 4).

2.1.10

RCL (RAM clear)
The RCL pin is used to clear all 114 storage bytes, excluding clock and control registers, of the array to FF(hex) value. The array will be cleared when the RCL pin is held low for at least 100 ms with the oscillator running. Usage of this pin does not affect battery load. This function is applicable only when VCC is applied.

10/36

M48T86

Operation

2.1.11

R/W (read/write input)
The R/W pin is used to latch data into the M48T86 and provides functionality similar to W in other memory systems.

2.1.12

Non-volatile RAM
The 114 general-purpose non-volatile RAM bytes are not dedicated to any special function within the M48T86. They can be used by the processor program as non-volatile memory and are fully accessible during the update cycle.

Figure 5.

Intel bus read AC waveform
tCYC AS tASW DS tDSL R/W tDAS E tAS AD0-AD7 tAH tDHR tCS tOD tCH tDSH tASD

AI01647

Figure 6.

Intel bus write mode AC waveform
tCYC AS tDAS DS tDSL R/W tCS E tAS AD0-AD7 tAH tDW tDHW tCH tDSH tASW tASD

AI01648

11/36

Operation Figure 7. Motorola bus read/write mode AC waveforms

M48T86

AS tDAS tASW tASD tCYC DS tDSL tRWS R/W tCS E tAH tAS AD0-AD7 (Write) tAS tAH AD0-AD7 (Read)
AI01649

tDSH tRWH

tCH

tDW

tDHW

tOD tDHR

12/36

M48T86 Table 2.
Symbol t CYC t DSL t DSH tRWH tRWS tCS tCH tDHR tDHW tAS tAH tDAS tASW tASD tOD tDW tBUC tPI(2) tUC Cycle time Pulse width, data strobe low or R/W high Pulse width, data strobe high or R/W low R/W hold time R/W setup time Chip select setup time Chip select hold time READ data hold time WRITE data hold time Address setup time Address hold time Delay time, data strobe to address strobe rise Pulse width address strobe high Delay time, address strobe to data strobe rise Output data delay time from data strobe rise WRITE setup time Delay time before update cycle Periodic interrupt time interval Time of update cycle 30 244 1

Operation AC characteristics
Parameter(1) Min 160 80 55 0 10 5 0 0 0 20 5 10 30 35 50 25 M48T86 Unit Typ Max ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns s

s

1. Valid for ambient operating temperature: TA = 0 to 70C; VCC = 4.5 to 5.5 V (except where noted). 2. See Table 4 on page 18.

13/36

Clock operations

M48T86

3
3.1

Clock operations
Address map
The address map of the M48T86 is shown in Figure 8. It consists of 114 bytes of user RAM, 10 bytes of RAM that contain the RTC time, calendar and alarm data, and 4 bytes which are used for control and status. All bytes can be read or written to except for the following: 1. 2. Registers C & D are "Read only." Bit 7 of Register A is "Read only."

The contents of the four Registers A, B, C, and D are described in the "Registers" section.

3.2

Time, calendar, and alarm locations
The time and calendar information is obtained by reading the appropriate memory bytes. The time, calendar, and alarm registers are set or initialized by writing the appropriate RAM bytes. the contents of the time, calendar, and alarm bytes can be either binary or binarycoded decimal (BCD) format. Before writing the internal time, calendar, and alarm register, the SET bit (Register B; Bit 7) should be written to a logic '1.' This will prevent updates from occurring while access is being attempted. In addition to writing the time, calendar, and alarm registers in a selected format (binary or BCD), the data mode (DM) bit (Register B; Bit 2), must be set to the appropriate logic level ('1' signifies binary data; '0' signifies binary coded decimal (BCD data). All time, calendar, and alarm bytes must use the same data mode. The SET bit should be cleared after the data mode bit has been written to allow the real-time clock to update the time and calendar bytes. Once initialized, the real-time clock makes all updates in the selected mode. The data mode cannot be changed without reinitializing the ten data bytes. Table 3 on page 15 shows the binary and BCD formats of the time, calendar, and alarm locations. The 24/12 bit (Register B; Bit 1) cannot be changed without reinitializing the hour locations. When the 12-hour format is selected, a logic '1' in the high order bit of the hours byte represents PM. The time, calendar, and alarm bytes are always accessible because they are double-buffered. Once per second the ten bytes are advanced by one second and checked for an alarm condition. If a READ of the time and calendar data occurs during an update, a problem exists where data such as seconds, minutes, or hours may not correlate. However, the probability of reading incorrect time and calendar data is low. Methods of avoiding possible incorrect time and calendar READs are reviewed later in this text.

14/36

M48T86 Figure 8. Address map

Clock operations

0 14 BYTES 13 14 CLOCK AND CONTROL STATUS REGISTERS

00

0 1 2 3 4 5 6 7 8 9

SECONDS SECONDS ALARM MINUTES MINUTES ALARM HOURS HOURS ALARM DAY OF WEEK DATE OF MONTH MONTH YEAR REGISTER A REGISTER B REGISTER C REGISTER D BCD OR BINARY FORMAT

0D 0E

114 BYTES

STORAGE REGISTERS

10 11 12 13

127

7F
AI01650

Table 3.
Address 0 1 2 3

Time, calendar, and alarm formats
Range RTC bytes Decimal Seconds Seconds alarm Minutes Minutes alarm Hours, 12-hrs 0-59 0-59 0-59 0-59 1-12 0-23 1-12 0-23 1 -7 1-31 1-12 0-99 Binary 00-3B 00-3B 00-3B 00-3B 01-0C AM 81-8C PM 00-17 01-0C AM 81-8C PM 00-17 01-07 01-1F 01-0C 00-63 BCD 00-59 00-59 00-59 00-59 01-12 AM 81-92 PM 00-23 01-12 AM 81-92 PM 00-23 01-07 01-31 01-12 00-99

4 Hours, 24-hrs Hours alarm, 12-hrs 5 Hours alarm, 24-hrs 6 7 8 9 Day of week (1 = Sun) Day of month Month Year

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Clock operations

M48T86

3.3

Interrupts
The RTC plus RAM includes three separate, fully automatic sources of interrupt (alarm, periodic, update-in-progress) available to a processor. The alarm interrupt can be programmed to occur at rates from once per second to once per day. The periodic interrupt can be selected from rates of 500 ms to 122 s. The update-ended interrupt can be used to indicate that an update cycle has completed. The processor program can select which interrupts, if any, are going to be used. Three bits in Register B enable the interrupts. Writing a logic '1' to an interrupt-enable bit (Register B; Bit 6 = PIE; Bit 5 = AIE; Bit 4 = UIE) permits an interrupt to be initialized when the event occurs. A '0' in an interrupt-enable bit prohibits the IRQ pin from being asserted from that interrupt condition. If an interrupt flag is already set when an interrupt is enabled, IRQ is immediately set at an active level, although the interrupt initiating the event may have occurred much earlier. As a result, there are cases where the program should clear such earlier initiated interrupts before first enabling new interrupts. When an interrupt event occurs, the related flag bit (Register C; Bit 6 = PF; Bit 5 = AF; Bit 4 = UF) is set to a logic '1.' These flag bits are set independent of the state of the corresponding enable bit in Register B and can be used in a polling mode without enabling the corresponding enable bits. The interrupt flag bits are status bits which software can interrogate as necessary. When a flag is set, an indication is given to software that an interrupt event has occurred since the flag bit was last read; however, care should be taken when using the flag bits as all are cleared each time Register C is read. Double latching is included with Register C so that bits which are set remain stable throughout the READ cycle. All bits which are set high are cleared when read. Any new interrupts which are pending during the READ cycle are held until after the cycle is completed. One, two, or three bits can be set when reading Register C. Each utilized flag bit should be examined when read to ensure that no interrupts are lost. The second flag bit usage method is with fully enabled interrupts. When an interrupt flag bit is set and the corresponding enable bit is also set, the IRQ pin is asserted low. IRQ is asserted as long as at least one of the three interrupt sources has its flag and enable bits both set. The IRQF bit (Register C; Bit 7) is a '1' whenever the IRQ pin is being driven low. Determination that the RTC initiated an interrupt is accomplished by reading Register C. A logic '1' in the IRQF bit indicates that one or more interrupts have been initiated by the M48T86. The act of reading Register C clears all active flag bits and the IRQF bit.

3.4

Periodic interrupt
The periodic interrupt will cause the IRQ pin to go to an active state from once every 500 ms to once every 122 s. This function is separate from the alarm interrupt which can be output from once per second to once per day. The periodic interrupt rate is selected using the same Register A bits which select the square wave frequency (see Table 4 on page 18). Changing the Register A bits affects both the square wave frequency and the periodic interrupt output. However, each function has a separate enable bit in Register B. The periodic interrupt is enabled by the PIE bit (Register B; Bit 6). The periodic interrupt can be used with software counters to measure inputs, create output intervals, or await the next needed software function.

16/36

M48T86

Clock operations

3.5

Alarm interrupt
The alarm interrupt provides the system processor with an interrupt when a match is made between the RTC's hours, minutes, and seconds bytes and the corresponding alarm bytes. The three alarm bytes can be used in two ways. First, when the alarm time is written in the appropriate hours, minutes, and seconds alarm locations, the alarm interrupt is initiated at the specified time each day if the Alarm Interrupt Enable bit (Register B; Bit 5) is high. The second use is to insert a "Don't care" state in one or more of the three alarm bytes. The "Don't care" code is any hexadecimal value from C0 to FF. The two most significant bits of each byte set the "Don't care" condition when at logic '1.' An alarm will be generated each hour when the "Don't care" is are set in the hours byte. Similarly, an alarm is generated every minute with "Don't care" codes in the hour and minute alarm bytes. The "Don't care" codes in all three alarm bytes create an interrupt every second.

3.6

Update cycle interrupt
After each update cycle, the Update Cycle Ended Flag bit (UF) (Register C; Bit 4) is set to a '1.' If the Update Interrupt Enable bit (UIE) (Register B; Bit 4) is set to a '1,' and the SET bit (Register B; Bit 7) is a '0,' then an interrupt request is generated at the end of each update cycle.

3.7

Oscillator control bits
When the M48T86 is shipped from the factory the internal oscillator is turned off. This feature prevents the lithium energy cell from being discharged until it is installed in a system. A pattern of "010" in Bits 4-6 of Register A will turn the oscillator on and enable the countdown chain. A pattern of "11X" will turn the oscillator on, but holds the countdown chain of the oscillator in reset. All other combinations of Bits 4-6 keep the oscillator off.

3.8

Update cycle
The M48T86 executes an update cycle once per second regardless of the SET bit (Register B; Bit 7). When the SET bit is asserted, the user copy of the double buffered time, calendar, and alarm bytes is frozen and will not update as the time increments. However, the time countdown chain continues to update the internal copy of the buffer. This feature allows accurate time to be maintained, independent of reading and writing the time, calendar, and alarm buffers. This also guarantees that the time and calendar information will be consistent. The update cycle also compares each alarm byte with the corresponding time byte and issues an alarm if a match or if a "Don't care" code is present in all three positions. There are three methods of accessing the real time clock that will avoid any possibility of obtaining inconsistent time and calendar data. The first method uses the update-ended interrupt. If enabled, an interrupt occurs after every update cycle which indicates that over 999ms are available to read valid time and date information. If this interrupt is used, the IRQF Bit (Register C; Bit 7) should be cleared before leaving the interrupt routine. A second method uses the Update-In-Progress (UIP) bit (Register A; Bit 7) to determine if the update cycle is in progress. The UIP bit will pulse once per second. After the UIP bit goes high, the update transfer occurs 244 s later. If a low is read on the UIP bit, the user has at least 244 s before the time/calendar data will be changed. Therefore, the user

17/36

Clock operations

M48T86

should avoid interrupt service routines that would cause the time needed to read valid time/calendar data to exceed 244 s. The third method uses a periodic interrupt to determine if an update cycle is in progress. The UIP bit is set high between the setting of the PF bit (Register C; Bit 6). Periodic interrupts that occur at a rate greater than tBUC allow valid time and date information to be reached at each occurrence of the periodic interrupt.The READs should be completed within 1/(tPL/2 + tBUC) to ensure that data is not read during the update cycle.

3.9

Square wave output selection
Thir teen of the 15 divider taps are made available to a 1-of-15 selector, as shown in the block diagram of Figure 4 on page 8. The purpose of selecting a divider tap is to generate a square wave output signal on the SQW pin. The RS3-RS0 bits in Register A establish the square wave output frequency. These frequencies are listed in Table 4 on page 18. The SQW frequency selection shares the 1-of-15 selector with the periodic interrupt generator. Once the frequency is selected, the output of the SQW pin can be turned on and off under program control with the Square Wave Enabled (SQWE) bit. Table 4. Square wave frequency/periodic interrupt rate
Register A bits RS3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 RS2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 RS1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 RS0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Square wave Frequency None 256 128 8.192 4.096 2.048 1.024 512 256 128 64 32 16 8 4 2 Hz Hz kHz kHz kHz kHz Hz Hz Hz Hz Hz Hz Hz Hz Hz Units Periodic interrupt Period None 3.90625 7.8125 122.070 244.141 488.281 976.5625 1.953125 3.90625 7.8125 15.625 31.25 62.5 125 250 500 ms ms us us us us ms ms ms ms ms ms ms ms ms Units

18/36

M48T86

Clock operations

3.10
3.10.1

Register A
UIP update in progress
The Update in Progress (UIP) bit is a status flag that can be monitored. When the UIP bit is '1,' the update transfer will soon occur (see Figure 9). When UIP is a '0,' the update transfer will not occur for at least 244 s. The time, calendar, and alarm information in RAM is fully available for access when the UIP bit is '0.' The UIP bit is "Read only" and is not affected by RST. Writing the SET bit in Register B to a '1' inhibits any update transfer and clears the UIP Status bit.

3.10.2

OSC0, OSC1, OSC2 oscillator control
These three bits are used to control the oscillator and reset the countdown chain. A pattern of "010" enables operation by turning on the oscillator and enabling the divider chain. A pattern of 11X turns the oscillator on, but keeps the frequency divider disabled. When "010" is written, the first update begins after 500 ms.

3.10.3

RS3, RS2, RS1, RS0
These four rate-selection bits select one of the 13 taps on the 15-stage divider or disable the divider output. The tap selected may be used to generate an output square wave (SQW pin) and/or a periodic interrupt. The user may do one of the following: 1. or 2. or 3. or 4. Enable neither. Table 4 on page 18 lists the periodic interrupt rates and the square wave frequencies that may be chosen with the RS bits. These four READ/WRITE bits are not affected by RST. Enable both at the same time and same rate; Enable the SQW output with the SQWE bit; Enable the interrupt with the PIE bit;

Table 5.
BIT7 UIP

Register A MSB
BIT6 OSC2 BIT5 OSC1 BIT4 OSC0 BIT3 RS3 BIT2 RS2 BIT1 RS1 BIT0 RS0

Figure 9.

Update period timing and UIP

UPDATE PERIOD (1sec)

UIP

tBUC

tUC
AI01651

19/36

Clock operations

M48T86

3.11
3.11.1

Register B
SET
When the SET bit is a '0,' the update transfer functions normally by advancing the counts once per second. When the SET bit is written to a '1,' any update transfer is inhibited and the program may initialize the time and calendar bytes without an update occurring. READ cycles can be executed in a similar manner. SET is a READ/WRITE bit which is not modified by RST or internal functions of the M48T86.

3.11.2

PIE: periodic interrupt enable
The Periodic Interrupt Enable bit (PIE) is a READ/WRITE bit which allows the Periodic Interrupt Flag (PF) bit in Register C to cause the IRQ pin to be driven low (see Figure 10 on page 21 for the relationship between PIE and UIE). When the PIE bit is set to '1,' periodic interrupts are generated by driving the IRQ pin low at a rate specified by the RS3-RS0 bits of Register A. A '0' in the PIE bit blocks the IRQ output from being driven by a periodic interrupt, but the Periodic Flag (PF) bit is still set at the periodic rate. PIE is not modified by any internal M48T86 functions, but is cleared to '0' on RST.

3.11.3

AIE: alarm interrupt enable
The Alarm Interrupt Enable (AIE) bit is a READ/WRITE bit which, when set to a '1,' permits the Alarm Flag (AF) bit in Register C to assert IRQ. An alarm interrupt occurs for each second that the three time bytes equal the three alarm bytes including a "Don't care" alarm code of binary 1XXXXXXX. When the AIE bit is set to '0,' the AF bit does not initiate the IRQ signal. The RST pin clears AIE to '0.' The internal functions of the M48T86 do not affect the AIE Bit.

3.11.4

UIE: update ended interrupt enable
The Update Ended Interrupt Enable (UIE) bit is a READ/WRITE bit which enables the Update End Flag (UF) bit in Register C to assert IRQ. A transition low on the RST pin or the SET bit going high clears the UIE bit.

3.11.5

SQWE: square wave enable
When the Square Wave Enable (SQWE) bit is set to a '1,' a square wave signal is driven out on the SQW pin. The frequency is determined by the rate-selection bits RS3-RS0. When the SQWE bit is set to '0,' the SQW pin is held low. The SQWE bit is cleared by the RST pin. SQWE is a READ/WRITE bit.

3.11.6

DM: data mode
The Data Mode (DM) bit indicates whether time and calendar information are in binary or BCD format. The DM bit is set by the program to the appropriate format and can be read as required. This bit is not modified by internal function or RST. A '1' in DM signifies binary data and a '0' specifies binary coded decimal (BCD) data.

20/36

M48T86

Clock operations

3.11.7

24/12
The 24/12 Control bit establishes the format of the hours byte. A '1' indicates the 24-hour mode and a '0' indicates the 12-hour mode. This bit is READ/WRITE and is not affected by internal functions or RST.

3.11.8

DSE: daylight savings enable
The Daylight Savings Enable (DSE) bit is a READ/WRITE bit which enables two special updates when set to a '1.' On the first Sunday in April, the time increments from 1:59:59AM to 3:00:00 AM. On the last Sunday in October, when the time reaches 1:59:59 AM, it changes to 1:00:00 AM. These special updates do not occur when the DSE bit is a '0.' This bit is not affected by internal functions or RST.

Table 6.
BIT7 SET

Register B MSB
BIT6 PIE BIT5 AIE BIT4 UIE BIT3 SQWE BIT2 DM BIT1 24/12 BIT0 DSE

Figure 10. Update-ended/periodic interrupt relationship
UPDATE PERIOD (1sec)

UIP

tBUC tPI PF tPI tPI

tUC

UF

AI01652B

3.12
3.12.1

Register C
IRQF: interrupt request flag
The Interrupt Request Flag (IRQF) bit is set to a '1' when one or more of the following are true: PF = PIE = 1 AF = AIE = 1 UF = UIE = 1 (e.g., IRQF = PF*PIE+AF*AIE+UF*UIE)

21/36

Clock operations

M48T86

3.12.2

PF: periodic interrupt flag
The Periodic Interrupt Flag (PF) is a "Read only" bit which is set to a '1' when an edge is detected on the selected tap of the divider chain. The RS3-RS0 bits establish the periodic rate. PF is set to a '1' independent of the state of the PIE Bit. The IRQ signal is active and will set the IRQF bit. The PF bit is cleared by a RST or a software READ of Register C.

3.12.3

AF: alarm flag
A '1' in the AF (Alarm Interrupt Flag) bit indicates that the current time has matched the alarm time. If the AIE bit is also a '1,' the IRQ pin will go low and a '1' will appear in the IRQF Bit. A RST or a READ of Register C will clear AF.

3.12.4

UF: update ended interrupt flag
The Update Ended Interrupt Flag (UF) bit is set after each update cycle. When the UIE bit is set to a '1,' the '1' in the UF bit causes the IRQF bit to be a '1.' This will assert the IRQ pin. UF is cleared by reading Register C or a RST.

3.12.5

BIT 0 through 3: unused bits
Bit 3 through Bit 0 are unused. These bits always read '0' and cannot be written.

3.13
3.13.1

Register D
VRT: valid RAM and time
The Valid RAM and Time (VRT) bit is set to the '1' state by STMicroelectronics prior to shipment. This bit is not writable and should always be a '1' when read. If a '0' is ever present, an exhausted internal lithium cell is indicated and both the contents of the RTC data and RAM data are questionable. This bit is unaffected by RST.

3.13.2

BIT 0 through 6: unused bits
The remaining bits of Register D are not usable. They cannot be written and when read, they will always read '0.' Table 7.
BIT7 IRQF

Register C MSB
BIT6 PF BIT5 AF BIT4 UF BIT3 0 BIT2 0 BIT1 0 BIT0 0

Table 8.
BIT7 VRT

Register D MSB
BIT6 0 BIT5 0 BIT4 0 BIT3 0 BIT2 0 BIT1 0 BIT0 0

22/36

M48T86

Clock operations

3.14

VCC noise and negative going transients
ICC transients, including those produced by output switching, can produce voltage fluctuations, resulting in spikes on the VCC bus. These transients can be reduced if capacitors are used to store energy which stabilizes the VCC bus. The energy stored in the bypass capacitors will be released as low going spikes are generated or energy will be absorbed when overshoots occur. A ceramic bypass capacitor value of 0.1 F (as shown in Figure 11) is recommended in order to provide the needed filtering. In addition to transients that are caused by normal SRAM operation, power cycling can generate negative voltage spikes on VCC that drive it to values below VSS by as much as one volt. These negative spikes can cause data corruption in the SRAM while in battery backup mode. To protect from these voltage spikes, it is recommended to connect a schottky diode from VCC to VSS (cathode connected to VCC, anode to VSS). Schottky diode 1N5817 is recommended for through hole and MBRS120T3 is recommended for surface mount. Figure 11. Supply voltage protection

VCC VCC

0.1F

DEVICE

VSS

AI02169

23/36

Maximum ratings

M48T86

4

Maximum ratings
Stressing the device above the rating listed in the absolute maximum ratings table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the Operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents. Table 9.
Symbol TA TSTG TSLD(1),(2),(3) VIO VCC PD

Absolute maximum ratings
Parameter Ambient operating temperature Storage temperature (VCC off, oscillator off) Lead solder temperature for 10 seconds Input or output voltages Supply voltage Power dissipation Value 0 to 70 40 to 85 260 0.3 to 7.0 0.3 to 7.0 1 Unit C C C V V W

1. For DIP package: soldering temperature not to exceed 260C for 10 seconds (total thermal budget not to exceed 150C for longer than 30 seconds). 2. For SOH28 package, standard (SnPb) lead finish: reflow at peak temperature of 225C (the time above 220C must not exceed 20 seconds). 3. For SOH28 package, lead-free (Pb-free) lead finish: reflow at peak temperature of 260C (the time above 255C must not exceed 30 seconds).

Warning:

Negative undershoots below 0.3 V are not allowed on any pin while in the battery backup mode.

Warning:

Do NOT wave solder SOIC to avoid damaging SNAPHAT sockets.

24/36

M48T86

DC and AC parameters

5

DC and AC parameters
This section summarizes the operating and measurement conditions, as well as the DC and AC characteristics of the device. The parameters in the following DC and AC Characteristic tables are derived from tests performed under the measurement conditions listed in the relevant tables. Designers should check that the operating conditions in their projects match the measurement conditions when using the quoted parameters. Table 10. Operating and AC measurement conditions
Parameter Supply voltage (VCC) Ambient operating temperature (TA) Load capacitance (CL) Input rise and fall times Input pulse voltages Input and output timing ref. voltages M48T86 4.5 to 5.5 0 to 70 100 5 0 to 3 1.5 Unit V C pF ns V V

Note:

Output Hi-Z is defined as the point where data is no longer driven. Figure 12. AC testing load circuit (no IRQ)
5V

960 FOR ALL OUTPUTS EXCEPT IRQ 510 50pF

AI01644

25/36

DC and AC parameters Figure 13. AC testing load circuit (with IRQ)

M48T86

5V

1.15k

IRQ

130pF

AI01645

Table 11.
Symbol CIN CIO(3)

Capacitance
Parameter(1)(2) Input capacitance Input / output capacitance Min M ax 7 5 Unit pF pF

1. Effective capacitance measured with power supply at 5 V; sampled only, not 100% tested. 2. At 25C, f = 1 MHz. 3. Outputs deselected.

Table 12.
Symbol ILI ILO
(2)

DC characteristics
Parameter Input leakage current Output leakage current Supply current Input low voltage Input high voltage Output low voltage IOL = 4 mA IOL = 0.5 mA IOH = 1 mA 2.4 Test Condition(1) 0V VIN VCC 0V VOUT VCC Outputs open 0.3 2.2 Min Max 1 1 15 0.8 VCC + 0.3 0.4 0.4 Unit A A mA V V V V V

ICC VIL VIH VOL VOH

Output low voltage (IRQ) Output high voltage

1. Valid for ambient operating temperature: TA = 0 to 70C; VCC = 4.5 to 5.5 V (except where noted). 2. Outputs deselected.

26/36

M48T86 Figure 14. Power down/up mode AC waveforms
VCC 4.5V VPFD VSO tF

DC and AC parameters

tR

trec E

AI01646

Table 13.

Power down/up mode AC characteristics
Parameter(1) VCC fall time VCC rise time VPFD to E high Min 300 100 20 200 Max Unit s s ms

Symbol tF(2) tR trec

1. Valid for ambient operating temperature: TA = 0 to 70C; VCC = 4.5 to 5.5 V (except where noted). 2. VCC fall time of less than tF may result in deselection/write protection not occurring until 200 s after VCC passes VPFD.

Table 14.
Symbol VPFD VSO tDR(3)

Power down/up trip points DC characteristics
Parameter(1)(2) Power-fail deselect voltage Battery backup switchover voltage Expected data retention time 10 Min 4.0 3.0 Typ Max 4.35 Unit V V YEARS

P

1. Valid for ambient operating temperature: TA = 0 to 70C; VCC = 4.5 to 5.5 V (except where noted). 2. All voltages referenced to VSS. 3. At 25C, VCC = 0 V.

27/36

Package mechanical data

M48T86

6

Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available at: www.st.com. ECOPACK is an ST trademark.

28/36

M48T86

Package mechanical data Figure 15. PCDIP24 24-pin plastic DIP, battery CAPHATTM, package outline

A2

A

A1 B1 B e3 D
N

L eA

C

e1

E
1 PCDIP

Note:

Drawing is not to scale. Table 15. PCDIP24 24-pin plastic DIP, battery CAPHATTM, package mechanical data
mm Symb Typ A A1 A2 B B1 C D E e1 e3 eA L N Min 8.89 0.38 8.36 0.38 1.14 0.20 34.29 17.83 2.29 25.15 15.24 3.05 24 Max 9.65 0.76 8.89 053 1.78 0.31 34.80 18.34 2.79 30.73 16.00 3.81 Typ Min 0.3500 0.0150 0.3291 0.0150 0.0449 0.0079 1.3500 0.7020 0.0902 0.9902 0.6000 0.1201 24 Max 0.3799 0.0299 0.3500 0.0209 0.0701 0.0122 1.3701 0.7220 0.1098 1.2098 0.6299 0.1500 inches

29/36

Package mechanical data

M48T86

Figure 16. SOH28 28-lead plastic small outline, 4-socket SNAPHAT, package outline

A2 B e

A C eB CP

D
N

E

H A1 L

1 SOH-A

Note:

Drawing is not to scale. Table 16. SOH28 28-lead plastic small outline, 4-socket battery SNAPHAT, package mechanical data
mm Symb Typ A A1 A2 B C D E e eB H L a N CP 1.27 0.05 2.34 0.36 0.15 17.71 8.23 3.20 11.51 0.41 0 28 0.10 Min Max 3.05 0.36 2.69 0.51 0.32 18.49 8.89 3.61 12.70 1.27 8 0.0500 0.0020 0.0921 0.0142 0.0059 0.6972 0.3240 0.1260 0.4531 0.0161 0 28 0.0039 Typ Min Max 0.1201 0.0142 0.1059 0.0201 0.0126 0.7280 0.3500 0.1421 0.5000 0.0500 8 inches

30/36

M48T86

Package mechanical data Figure 17. SH 4-pin SNAPHAT housing for 48 mAh battery and crystal, package outline

A1

A2 A A3

eA D

B eB

L

E

SH

Note:

Drawing is not to scale. Table 17. SH 4-pin SNAPHAT housing for 48 mAh battery and crystal, package mechanical data
mm Symb Typ A A1 A2 A3 B D E eA eB L 0.46 21.21 14.22 15.55 3.20 2.03 6.73 6.48 Min Max 9.78 7.24 6.99 0.38 0.56 21.84 14.99 15.95 3.61 2.29 0.0181 0.8350 0.5598 0.6122 0.1260 0.0799 0.2650 0.2551 Typ Min Max 0.3850 0.2850 0.2752 0.0150 0.0220 0.8598 0.5902 0.6280 0.1421 0.0902 inches

31/36

Package mechanical data

M48T86

Figure 18. SH 4-pin SNAPHAT housing for 120 mAh battery and crystal, package outline

A1

A2 A A3

eA D

B eB

L

E

SHTK-A

Note:

Drawing is not to scale. Table 18. SH 4-pin SNAPHAT housing for 120 mAh battery and crystal, package mechanical data
mm Symb Typ A A1 A2 A3 B D E eA eB L 0.46 21.21 17.27 15.55 3.20 2.03 8.00 7.24 Min Max 10.54 8.51 8.00 0.38 0.56 21.84 18.03 15.95 3.61 2.29 0.018 0.835 0.680 0.612 0.126 0.080 0.315 0.285 Typ Min Max 0.415 .0335 0.315 0.015 0.022 0.860 .0710 0.628 0.142 0.090 inches

32/36

M48T86

Part numbering

7

Part numbering
Table 19.
Example: Device type M48T

Ordering information scheme
M48T 86 MH 1 E

Supply voltage and write protect voltage 86 = VCC = 4.5 to 5.5 V; VPFD = 4.2 to 4.5 V Package PC = PCDIP24 MH(1) = SOH28

Temperature range 1 = 0 to 70C

Shipping method For SOH28: Blank = Tubes (Not for New Design - use E) E = Lead-free package (ECOPACK), tubes F = Lead-free package (ECOPACK), tape & reel TR = Tape & reel (Not for New Design - use F) For PCDIP24: Blank = Tubes
1. The SOIC package (SOH28) requires the SNAPHAT battery/crystal package which is ordered separately under the part number "M4T28-BR12SH" in plastic tube or "M4T28-BR12SHTR" in tape & reel form (see Table 20).

Warning:

Do not place the SNAPHAT battery package "M4TXXBR12SH" in conductive foam as it will drain the lithium button-cell battery.

For other options, or for more information on any aspect of this device, please contact the ST sales office nearest you. Table 20. SNAPHAT battery table
Description Lithium battery (48 mAh) SNAPHAT Lithium battery (120 mAh) SNAPHAT Package SH SH

Part number M4T28-BR12SH M4T32-BR12SH

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Environmental information

M48T86

8

Environmental information
Figure 19. Recycling symbols

This product contains a non-rechargeable lithium (lithium carbon monofluoride chemistry) button cell battery fully encapsulated in the final product. Recycle or dispose of batteries in accordance with the battery manufacturer's instructions and local/national disposal and recycling regulations. Please refer to the following web site address for additional information regarding compliance statements and waste recycling. Go to www.st.com/rtc, then select "Lithium Battery Recycling" from "Related Topics".

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M48T86

Revision history

9

Revision history
Table 21.
Date Mar-1999 04-May-2000 31-Jul-2001 20-May-2002 01-Apr-2003 02-Apr-2004 20-Feb-2007 05-Jul-2007

Document revision history
Revision 1 1.1 2 2.1 3 4 5 6 First Issue Page layout changed Reformatted; temp/voltage info. added to tables (Table 12, 2, 13,14) Modify reflow time and temperature footnotes (Table 9) V2.2 template applied; test condition updated (Table 14 ) Reformatted; update Lead-free package information (Table 9,19) Updated cover page (features) and Section 2: Operation on page 9. Added RoHS compliant and lead-free second level interconnect information to cover page and Section 6: Package mechanical data; updated Figure 5 and 7. Updated cover page as product "not recommended for new design"; updated footnotes for Table 9; updated text in Section 6: Package mechanical data; added Section 8: Environmental information; minor formatting changes Changes

04-Dec-2008

7

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M48T86

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