TPS6755

ADJUSTABLE INVERTING DC/DC CONVERTER

SLVS155A – NOVEMBER 1996 REVISED DECEMBER 1996

5

POST OFFICE BOX 655303

SS clamp

The SS clamp circuit limits the signal level on error-amplifier output during start-up. The voltage on SS is

amplified and used to override the error-amplifier output until the error-amplifier voltage rises above that output,

at which point the error amplifier takes over. This prevents the input to the PWM comparator from exceeding

its common-mode range (i.e., error amplifier output too high to be reached by the current ramp) by limiting the

maximum voltage on the error-amplifier output during start-up.

Soft start causes the output voltage to increase to the regulation point at the controlled rate. The voltage on the

charging soft-start capacitor gradually raises the clamp on the error amplifier output voltage, limiting surge

currents at power up by increasing the current limit threshold on a cycle-by-cycle basis. A soft-start cycle is

initiated when either the enable (EN) signal is switched high or an overcurrent fault condition triggers the

discharge of the soft-start capacitor.

DISSIPATION RATING TABLE

PACKAGE

TA ≤ 25°C

POWER RATING

DERATING FACTOR

ABOVE TA = 25°C

TA = 70°C

POWER RATING

TA = 85°C

POWER RATING

D

725 mW

5.8 mW/

°C

464 mW

377 mW

P

1175 mW

9.4 mW/

°C

752 mW

611 mW

–0.3 V to 9 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12.5 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FB (see Note 1)

25 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SS, COMP, EN voltage range (see Note 1)

. . . . . . . . . . . . . . . . . . . . . . . .

Peak switch current

2 A

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reference current

2.5 mA

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Continuous total power dissipation

See Dissipation Rating Table

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

–40

°C to 85°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

–65

°C to 150°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Lead temperature 1,6mm (1/16 inch) from case for 10 s

260

°C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and

functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not

implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTE 1: All voltage values are with respect to network terminal ground.

recommended operating conditions

MIN

NOM

MAX

UNIT

Supply voltage

2.7

9

V

Decoupling capacitor

1

µF

Input capacitor

47

µF

Reference capacitor

10

µF

Output capacitor

100

µF

Compensation capacitor

82

pF

Inductor

10

µH