NCP1338 查看數據表（PDF） - ON Semiconductor

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NCP1338

PWM Current-Mode Controller for Free Running Quasi-Resonant Operation

ON Semiconductor 

NCP1338

PIN FUNCTION DESCRIPTION

Pin No.

Symbol

Function

1

BO

Brown−out and external

triggering

2

FB

Sets the peak current

setpoint

3

CS

Current sense input and

overpower compensation

adjustment

4

GND

IC ground

5

DRV

Output driver

6

VCC

IC supply

8

HV

High−voltage pin

Description

• By connecting this pin to the input voltage through a resistor divider, the

controller ensures operation at a safe mains level, thanks to a 500 mV

brown−out comparator.

• If an external event brings this pin above 3.0 V, the controller’s output is

disabled.

• If an external event brings this pin above 5.0 V, the controller is

permanently latched−off.

• By connecting an optocoupler or an auxiliary winding to this pin, the peak

current setpoint is adjusted accordingly to the output power demand.

• When the requested peak current setpoint is below the internal standby

level, the device enters Soft−Skip mode.

• This pin senses the primary current and routes it to the internal comparator

via an L.E.B.

• Inserting a resistor in series with the pin allows to control the overpower

compensation level.

• To be connected to an external MOSFET.

• Connected to a tank capacitor (and possibly an auxiliary winding).

• When VCC reaches 18.6 V, an internal OVP stops the output pulses.

• Connected to the high−voltage rail, this pin injects a constant current into

the VCC bulk capacitor and ensures a clean lossless startup sequence.

BO

+

Cbulk

NCP1338

1

8

2

3

6

4

5

Rcomp

VCC

+

VOUT

+

VCC

Figure 1. Typical Application Schematic

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