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FR9701-1.1-FEB-2012

FR9701

85T

fitipower integrated technology lnc.

Functional Pin Description

Pin Name

Pin Function

BS

Bootstrap.

A 22nF capacitor is connected between SW and BS pins to drive the power switch’s gate above the

supply voltage.

GND

Ground Pin.

FB

Feedback.

An external resistor divider from the output to GND, tapped to the FB pin sets the output voltage.

EN

On/Off Control Input.

Pull EN above 1.2V and below 5V to turn the device on.

VIN

Power Supply Input.

Drive 4.5V to 23V voltage to this pin to power on this chip.

Connect a 10

μF ceramic bypass

capacitor between VIN and GND to eliminate noise.

SW

Switch Output.

Connect this pin to the switch end of the inductor.

Block Diagram

PWM

Control

Driver

Logic

BS

SW

R

OTP

UVLO

Current

Comparator

S

Oscillator

High-Side

MOSFET

ISEN

FB

0.805V

UVLO

&

POR

VIN

VCC

GND

Current

Limit

OTP

Internal

Regulator

VCC

EN

Error

Amplifier

950K

OVP

OVP

Figure 3. Block Diagram of FR9701