UCC29421, UCC29422, UCC39421, UCC39422

MULTIMODE HIGHFREQUENCY PWM CONTROLLER

SLUS246C − OCTOBER 1999 − REVISED FEBRUARY 2005

26

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

non−synchronous boost for higher output voltage applications (continued)

UDG−98212

RT

100 K

RCOMPC

COMP

Q1

(N)

RG1

4.7

RSENSE

0.05

Ω

COUT

100

µF

16V

CIN

100

µF

16V

0.1

µF

+VIN

12V

R3

249 K

1%

R2

17.8 K

1%

R1

11 K

1%

+

+

RSLOPE

1.5 K

CPOLE

1.25 V

3.0 V TO 8.0V

L1

6.8

µH

1

2

3

4

5

6

7

10

9

8

UCC39421

16

15

14

13

12

11

ISENSE

VOUT

RSEN

VGRECT

PGND

VGCHRG

VPUMP

CP

VIN

RSEL

RT

GND

PFM

FB

COMP

SYNC/SD

D1

MBR0530T

N/C

Figure 16. Non-Synchronous Boost Converter for Higher Output Voltages

UCC39422 features

The UCC39422 is a 20-pin device that adds a reset function and an uncommitted comparator to the UCC39421.

A simplified diagram of the reset circuit is shown in Figure 17.

UDG−98206

17

20

1

RESET

RSADJ

SQ

Q

R

1 µA

C RESET

+

+

8 pF

1.175 V

+

FB

g

m

=1/26 k

1.175 V

1.175 V

V

IN

Figure 17. Reset Circuitry