4-6

Rev. 1.0

11/2/99

US3022

BLOCK DIAGRAM

BLOCK DIAGRAM

Figure 1 - Simplified block diagram of the US3022.

PWM

Control

V12

V12

3022blk1-1.0

Osc

Slope

Comp

+

1.26V

4Bit

DAC

Enable

Soft

Start &

Fault

Logic

200uA

0.9Vset

1.1Vset

1.17Vset

Vset

Enable

UVLO

Vset

Enable

PGood

Vsen2

Drive4

Select

Drive3

Vsen1

Drive2

V5

V12

SS

Gnd

Fault / Rt

Phase

OCSet

LGate

UGate

Fb

Vsen4

Vsen3

PGnd

Over

Current

Over

Voltage

Vaux

Vref

VID3

VID2

VID1

VID0

R

3R

R

3R

1.5V

3.3V

Vsen5

Drive5

R

3R

2.5V

+

2V