ST619LB
DC-DC converter regulated 5 V charge pump
Features
Regulated 5 V 4 % charge pump Output current guaranteed over temperature: 20 mA (VI 2 V), 30 mA (VI 3 V) No inductors; very low EMI noise Uses small, inexpensive capacitors Logic controlled 1 A max shut-down supply current Shut down disconnects load from input Available in SO-8 and DIP-8 packages
SO-8
Description
The ST619LB is a step-up charge pump DC-DC converter which delivers a regulated 5 V 4 % output at 30 mA and over temperature. The input voltage range is 2 V to 3.6 V (two battery cells). It requires only four external capacitor: two 0.22 F flying capacitors, and 10 F capacitors at the input and output. Low operating supply current (typ. 200 A) make the device ideal for small, portable and battery powered applications. When shut down the load is disconnected from the input and the supply current is typically 0.02 A. The ST619LB is available in SO-8 package.
Table 1.
Device summary
Order codes ST619LB SO-8 (tape & reel) ST619LBDR
November 2007
Rev. 4
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ST619LB
Contents
1 2 3 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Operating principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Shut down mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 5 6 7
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1 7.2 7.3 Charge pump capacitors C1 and C2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Input and output capacitors C3 and C4 . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Layout consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8 9
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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ST619LB
Schematic
1
Figure 1.
Schematic
Schematic diagram
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Pin configuration
ST619LB
2
Figure 2.
Pin configuration
Pin connections (top view)
Table 2.
Pin n 1 2 3 4 5 6 7 8
Pin description
Symbol C1+ IN OUT C2+ C2GND SHDN C1Name and function Positive terminal for the first charge pump capacitor Input supply voltage 5V output voltage. VO=0V when in shutdown mode. Positive terminal for the second charge pump capacitor Negative terminal for the second charge pump capacitor Ground Active high C-MOS logic level shutdown input. SHDN is connected to GND for normal operation. Negative terminal for the first charge pump capacitor
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ST619LB
Operating principle
3
Operating principle
The ST619LB is able to provide a regulated 5 V output from a 2 V to 3.6 V (two battery cells) input. Internal charge pump and external capacitors generate the 5 V output, eliminating the need for inductors. The output voltage is regulated to 5 V, 4 % by a pulse skipping controller that turns on the charge pump when the output voltage begins to drop. To maintain the greatest efficiency the internal charge pump of the device operates as a voltage doubler when VI ranges from 3.0 V to 3.6 V and as a voltage triple when VI ranges from 2.0 V to 2.5 V. When VI ranges from 2.5 V to 3.0 V, the ST619LB switches between doubler and triple mode on alternating cycles, making a 2.5 x VI charge pump. To further enhance the efficiency over the input range, an internal comparator selects the higher of VI or VO to run the ST619LB's circuitry. With VI = 2 V and IO = 20 mA the typical efficiency value is 80%. In triple mode (see block diagram), when the S1 switches close, the S2 switches open and capacitors C1 and C2 charge up to VI. On the second half of the cycle, C1 and C2 are connected in series between IN and OUT when the S1 switches open and S2 switches close. In the doubler mode only C2 is used. During one oscillator cycle, energy is transferred from the input to the charge pump capacitors, and then from the charge pump capacitors to the output capacitors and load. The number of cycles within a given time frame increases as the load increases or as the input supply voltage decreases. In the limiting case, the charge pumps operate continuously, and the oscillator frequency is nominally 500 kHz.
3.1
Shut down mode
The ST619LB enters low power shut down mode when SHDN is a logic high. In shut down mode, OUT is disconnected from the IN and VO falls to 0V. The SHDN pin is connected to ground for normal operation. SHDN is a CMOS compatible input.
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Maximum ratings
ST619LB
4
Table 3.
Symbol VI VO VSHDN IO TSTG TOP
Maximum ratings
Absolute maximum ratings
Parameter DC input voltage Output voltage Shutdown input voltage Output current continuous Storage temperature range Operating junction temperature range Value -0.3 to 5.5 -0.3 to 5.5 -0.3 to (VI + 0.3) 120 -55 to +150 -40 to +85 Unit V V V mA C C
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. Thermal data
Parameter Thermal resistance junction-ambient (1) SO-8 160 Unit C/W
Table 4.
Symbol RthJA
1. This value depends from thermal design of PCB on which the device is mounted.
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ST619LB
Electrical characteristics
5
Table 5.
Symbol VI VO
Electrical characteristics
Electrical characteristics (VI = 2 to 3.6 V, C1 = C2 = 0.22 F, C3 = C4 = 10 F, TA = -40 to 85C, unless otherwise specified. Typical value are referred at TA = 25 C)
Parameter Input voltage Output voltage VI = 2 to 3.6V, IO =0 to 20mA VI = 3 to 3.6V, IO=0 to 30mA No load, Full load VI = 2 to 3V, No load VI = 3 to 3.6V, No load Shutdown supply current VI = 2 to 3.6V, No Load, VSHDN = VI VI = 3V, IO =20mA Efficiency VI = 3V, IO =30mA VI = 2V, IO =20mA fOSC VIH VIL IIH Switching frequency SHDN input threshold SHDN input threshold SHDN input current VSHDN = VI 0.005 Full load 0.7VI 0.4 1 Test conditions Min. 2 4.8 4.8 5 5 100 200 75 0.02 82 82 80 500 kHz V V A % 300 A 150 1 A Typ. Max. 3.6 5.2 5.2 Unit V V V mV
VRIPPLE Output voltage ripple Ii ISHDN No load supply current
Note:
Do not overload or short the output to ground. If the above conditions are not observed the device may be damaged.
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Typical performance characteristics
ST619LB
6
Figure 3.
Typical performance characteristics
No load supply current vs input voltage Figure 4. Shutdown supply current vs input voltage
Figure 5.
Maximum output current vs input voltage
Figure 6.
Output voltage vs output current
Figure 7.
Efficiency vs output current
Figure 8.
Efficiency vs input voltage
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ST619LB
Typical performance characteristics
Figure 9.
Output voltage vs input voltage
Figure 10. Start-up
Figure 11. Output voltage vs temperature
Figure 12. Line transient response
RL = 250
Figure 13. Load transient response
VI = 3 V, IO = 0 to 25 mA
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Application information
ST619LB
7
7.1
Application information
Charge pump capacitors C1 and C2
The values of charge pump capacitors C1 and C2 are critical to ensure adequate output current and avoid excessive peak currents. It is suggested to use values in the range of 0.22 F to 1.0 F and avoid the use of higher values of CO capacitors, in order to obtain best performance. Ceramic or tantalum capacitors are recommended.
7.2
Input and output capacitors C3 and C4
The type of input capacitor (C3) and output filter capacitor (C4) used is not critical, but it does affect performance. Tantalum, ceramics or aluminium electrolytic are suggested. For lowest ripple, use large, low effective series resistance (ESR) ceramic tantalum capacitors. If the input supply source impedance is very low, C3 can be omitted. The typical application circuit shows the component values for proper operation using minimal board space. The input bypass capacitor (C3) and output filter capacitor (C4) should be at least 10 F. Many capacitors exhibit 40% to 50% variation over temperature. Compensate for capacitor temperature coefficient by selecting a large nominal value to ensure proper operation over temperature.
7.3
Layout consideration
In the below figure, the typical application evaluation board of ST619LB is reported. A good layout ensures stability and helps maintain the output voltage under heavy loads. For best performance, use very short connections to the capacitors.
Figure 14. Typical application circuit
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ST619LB Figure 15. Typical application evaluation board
Application information
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Package mechanical data
ST619LB
8
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com.
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ST619LB
Package mechanical data
SO-8 mechanical data
Dim. A A1 A2 B C D E e H h L k ddd 0.1 5.80 0.25 0.40 mm. Min. 1.35 0.10 1.10 0.33 0.19 4.80 3.80 1.27 6.20 0.50 1.27 8 (max.) 0.04 0.228 0.010 0.016 Typ. Max. 1.75 0.25 1.65 0.51 0.25 5.00 4.00 Min. 0.053 0.04 0.043 0.013 0.007 0.189 0.150 0.050 0.244 0.020 0.050 inch. Typ. Max. 0.069 0.010 0.065 0.020 0.010 0.197 0.157
0016023/C
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Package mechanical data
ST619LB
Tape & reel SO-8 mechanical data
mm. Dim. Min. A C D N T Ao Bo Ko Po P 8.1 5.5 2.1 3.9 7.9 12.8 20.2 60 22.4 8 .5 5.9 2.3 4.1 8.1 0.319 0.216 0.082 0.153 0.311 Typ. Max. 330 13.2 0.504 0.795 2 .362 0.882 0.335 0.232 0.090 0.161 0.319 Min. Typ. Max. 12.992 0.519 inch.
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ST619LB
Revision history
9
Table 6.
Date
Revision history
Document revision history
Revision 3 4 Added Table 1. Changes
21-Jun-2004 07-Nov-2007
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ST619LB
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