ASIC

VC ORE

VC CI O

PTH12010L

1

10

4

5

6

2

3

9

Tra ck

GND

Inhibit

7

Vadj

Sense

+

C2

330 F

m

C4

330 F

m

C6

0.68 F

m

C5

0.1 F

m

C3

330 F

m

C1

330 F

m

R1

2kW

R5

10kW

R4

100kW

R3

11kW

R2

130 W

+

+

PTH12020W

7

10

4

5

6

2

3

9

Tra ck

V

I

V

I

V =12V

I

V 1=3.3V

O

V 2=1.8V

O

I 2

O

V

O

V

O

GND

Inhibit

1

Up

Adjust

+

TL7702B

V

CC

GND

SENSE

RESIN

REF

CT

RESET

RESET

8

7

2

1

3

5

6

4

+

Dn

Sense

8

8

PTH12040W

SLTS237G – DECEMBER 2004 – REVISED MARCH 2009............................................................................................................................................... www.ti.com

Figure 20. Application Circuit Demonstrating Prebias Startup

Note

1. The prebias start-up feature is not compatible with Auto-Track. If the rise in the output is limited by the

voltage applied to the Track control pin, the output sinks current during the period that the Track control

voltage is below that of the back-feeding source. For this reason, it is recommended that Auto-Track be

disabled when not being used. This is accomplished by connecting the Track pin to the input voltage, VI. This

raises the Track pin voltage well above the set-point voltage prior to the module’s start up, thereby defeating

the Auto-Track feature.

22

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