NCP1234 データシートの表示（PDF） - ON Semiconductor

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NCP1234

Fixed Frequency Current Mode Controller for Flyback Converters

ON Semiconductor 

NCP1234

SIMPLIFIED INTERNAL BLOCK SCHEMATIC

VDD

INTC

INTC

+

+

−

VOVP

blanking

tLatch(OVP)

HV

HV

Latch

1 kW

Vclamp

−

+

+

VOTP

blanking

tLatch(OTP)

S

Q

R

Soft−start

end

Reset

TSD

Latch

UVLO

VDD

IC Start

TSD

Dual HV

start−up

current source

TSD HV current

Reset

UVLO

VDD

Start

VCC

management

VFB(ref)

20 kW

−

+

+

Vskip

/5

slope

FB

comp.

VCC

HV sample

V to I

IOPC = 0.5m x

(VHV − 125)

VFB(OPC)

blanking

tLEB

CS

blanking

tBCS

PWM

+

−

Soft−start

+

−

Soft−start ramp Start

End tSSTART Reset

IC Start

IC Stop

Soft−start end

+

+

−

VILIM

ILIMIT

IC stop

Jitter

Sawtooth

Stop Foldback

Oscillator

S

Q

R

Clamp

ILIMIT

S

Fault Flag

Q

R

PWM

+

+

−

VCS(stop)

tfault timer

Fault

Protection

Mode

release

For

Autorecovery

protection

mode only

timer

tautorec

Reset

Figure 2. Simplified Internal Block Schematic

http://onsemi.com

3

Latch

TSD

UVLO

DRV

GND

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