NCP1254 查看數據表（PDF） - ON Semiconductor

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NCP1254

Current-Mode PWM Controller for Off-line Power Supplies featuring Peak Power Excursion

ON Semiconductor 

OPP

Vlatch

NCP1254

600−ns time

constant

OVP

gone?

Up counter

RST

4

S

Q

Q

R

Power on

reset

Jitter mod.

Vcc and logic

management

UVLO

double hiccup

Vdd power

on reset

100% to

25% change

VOVP

SC

Vcc

option

20 ms latch/AR

1−ms

blanking

65 kHz

clock

Rlimit

Vcc

Vref

Clamp

S

Q

Q

R

Frequency

increase to

130 kHz

Frequency

foldback

IpFlag,

PON reset

Vcc

Drv

VFswp

Vskip

Vfold

vdd

RFB

/4

FB

CS

VSC

LEB

Rramp

SC

4 ms

SS

The soft−start is

activated during:

Ip flag

− the startup sequence

− the auto−recovery burst mode

VFB < 1 V ? setpoint = 250 mV

VOPP

250 mV

peak current

freeze

Vlimit + VOPP

+

Vlimit

Figure 2. Internal Circuit Architecture

GND

http://onsemi.com

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