FAN604

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3

PIN FUNCTION DESCRIPTION

Pin No.

Pin Name

Description

1

HV

High Voltage. This pin connects to DC bus for high-voltage startup.

2

NC

No Connect.

3

CS

Current Sense. This pin connects to a current-sense resistor to sense the MOSFET current for Peak-Current-Mode

control for output regulation. The current sense information is also used to estimate the output current for CC

regulation.

4

GATE

PWM Signal Output. This pin has an internal totem-pole output driver to drive the power MOSFET. The gate

driving voltage is internally clamped at 7.5V.

5

VDD

Power Supply. IC operating current and MOSFET driving current are supplied through this pin. This pin is typically

connected to an external VDD capacitor.

6

VS

Voltage Sense. The VS voltage is used to detect resonant valleys for quasi-resonant switching. This pin detects

the output voltage information and diode current discharge time based on the auxiliary winding voltage. It also

senses input voltage for Brown-out protection.

7

CCR

Constant Current Reference. This pin connects to external resistor to program the reference voltage of constant

output current.

8

SD

Shut Down. This pin is implemented for external over-temperature-protect by connecting NTC thermistor.

9

FB

Feedback. Typically Opto-Coupler is connected to this pin to provide feedback information to the internal PWM

comparator. This feedback is used to control the duty cycle in CV regulation.

10

GND

Ground.

5.25V

FB

CS

LEB

VDD

HV

Start-up

HV

VS

7

CCR

1

S/H

S/H = Sampling and Hold

Valley

Detection

Forced Frequency

Modulation

OSC

3

6

9

VDD OVP Fault

VDD UVLO

17.2V/5.5V

5

Debounce

VD

D

C

Q

Q

CLK

VDD

Driver

Control

GATE

Maximum

On Time

4

Burst/Green

Mode

10

GND

Peak Current

Auto-Restart

Protection

OTP Fault

Brown OUT

VDD UVLO

VDD UVLO

5V

Brown IN

HV

5V

SD Fault

8

SD

SD Fault

VS Protection

5V

CS

Protection

Figure 2 FAN604 Block Diagram