ML4902

6

Figure 1. Typical VRM Circuit

UNDERVOLTAGE LOCKOUT

The ML4902 has hysteretic undervoltage lockout

supplies. During an input undervoltage condition, the

internal reference and voltage monitor circuits remain in

operation, but N DRV H and N DRV L are disabled and

the PWR GOOD output will be false (low).

COMPENSATION

The COMP pin is connected to the output of the

transconductance amplifier which forms the gain block

for the proportional control loop of the ML4902. An RC

network from this pin to GND is used to compensate the

amplifier.

VID4

R5

100

Ω

12VIN

5VIN

C4-C9

L2

1.4µH

R4

470k

Ω

C13

1nF

C14

220nF

16V

C20

22µF

25V

C10

220nF

16V

C12

220nF

16V

R3

1M

Ω

OUTEN

VID0

VID1

VID2

VID3

PWRGD

C3

C1

C2

Q1, Q2

2X IRF7413

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

R2

1k

Ω

C11

220nF

16V

Q3, Q4

2X IRF7413

VCCP

VSS

C1 - C9 - 1500µF, 6.3V, Sanyo 6MV1500GX

C15, C19 - 100nF ceramic

U1

ML4902

C15

C19

R1

12

Ω

C22

1nF

PROTECT

VDD

VCC

N DRV H

N DRV L

PWR GND

NC

COMP

ISENSE

VFB

D0

D1

D2

D3

RANGE

SHDN

NC

PWR GOOD

VREF

GND

L1

1µH