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TPS6734I

FIXED 12-V 120-mA BOOST-CONVERTER SUPPLY

SLVS127A – AUGUST 1995 – REVISED JANUARY 1999

1

POST OFFICE BOX 655303

3.75-V or Higher Input

Shutdown

120-mA Output)

Temperature Range

description

The TPS6734 is a fixed 12-V output boost converter capable of delivering 120 mA from inputs as low as

3.75 V. The device is pin-for-pin compatible with the MAX734 regulator and offers the following advantages:

lower supply current, wider operating input-voltage range, and higher output currents. As shown in Figure 1,

the only external components required are: an inductor, a Schottky rectifier, an output filter capacitor, an input

PCB space when implemented with surface-mount components. An enable input is provided to shut down the

converter and reduce the supply current to 3

µA when 12 V is not needed.

The TPS6734 is a 170-kHz current-mode PWM ( pulse-width modulation) controller with an n-channel MOSFET

power switch. Gate drive for the switch is derived from the 12-V output after start-up to minimize the die area

needed to realize the 0.7-

Ω MOSFET and improve efficiency at input voltages below 5 V. Soft start is

accomplished with the addition of one small capacitor. A 1.22-V reference (pin 2) is brought out for external use.

High efficiency at low supply voltages and low supply current in shutdown make the TPS6734 particularly

attractive for flash memory programming supplies, PCMCIA cards, and operational amplifiers in

battery-powered equipment. The TPS6734 is available in 8-pin DIP and SOIC packages and operates over a

free-air temperature range of – 40

°C to 85°C.

VCC

FB

OUT

GND

EN

REF

SS

COMP

1

2

3

4

8

7

6

5

TPS6734

0.001

µF

18

µH

1A, 20 V

VI

3.75 V to 12 V

ENABLE

+

33

µF

VO

12 V, 120 mA

Figure 1. Typical Operating Circuit

1

2

3

4

8

7

6

5

EN

REF

SS

COMP

FB

OUT

GND

D OR P PACKAGE

(TOP VIEW)

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright

© 1999, Texas Instruments Incorporated