F72820

Jul 2007

V0.24P

-3-

F72820

5V

PWM

CONTROLLER

VOUT

Q1

Q2

BOOT

VIN

Figure 2: Simplified power system diagram

5. Pin Description

AIN

- Input pin(Analog)

AOUT

- Output pin(Analog)

P

- Power

Pin No

Pin Name

TYPE

PWR

Description

1

BOOT

P

Provide ground reference voltage for high side MOSFET by bootstrap

circuit or ATX 12V.

2

UGATE

AOUT

BOOT

Higher gate drive output. Connect this pin to gate of the high side

MOSFET

3

GND

P

Power ground pin for the chip

4

LGATE

AOUT

VCC

Lower gate drive output. Connect this pin to gate of the low side

MOSFET

5

VCC

P

IC supply voltage. This voltage is monitored for power-on-reset purpose.

6

FB

AIN

VCC

Inverting input of the error amplifier used to compensate the feedback

loop of the PWM controller.

7

OCSET/SD

AOUT/AIN

VCC

This is multi-function pin. Connecting a resistor from this pin to drain of

high side MOSFET and an internal 40uA current source to ground.

OCSET voltage is reference for over current detect. When OCSET

voltage is under 1.25V, shut down function will be enabled.

8

PHASE

AIN

VCC

Connect to high side MOSFET source and monitor its voltage drop for

over current protection.