NCP1654BD200R2G 데이터 시트보기 (PDF) - ON Semiconductor

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NCP1654BD200R2G

Power Factor Controller for Compact and Robust, Continuous Conduction Mode Pre-Converters

ON Semiconductor 

NCP1654

Soft Start

The block diagram and timing diagram of soft start

function are as shown in Figure 42 and Figure 43. The

device provides no output (or no duty ratio) when the

Vcontrol is lower than VCONTROL(min). Vcontrol is pulled low

when:

• Brown−out, or

• Undervoltage Protection

When the IC recovers from one of the following

conditions; Undervoltage Lockout, Brown−out or

Undervoltage Protection, the 200 mA current source block

keeps off. Hence only the Operating Trans−conductance

Amplifier (OTA) raises the Vcontrol. And Vcontrol rises

slowly. This is to obtain a slow increasing duty cycle and

hence reduce the voltage and current stress on the

MOSFET. A soft−start operation is obtained.

Vdd

Off

Bias

BO UVLO UVP

SQ

RQ

Vdd

200 mA

Vfb

6

Vcontrol

5

-

95%

+

VREF

-

Vout Low Detect

±20 mA

VREF

+ OTA

BO UVLO

UVLO, BO, or UVP

Vdd

Vdd Rising

Vfb

Vout Low Detect

Set

Reset

Q

Period I

Figure 42. Soft Start Block Diagram

Period II

95% VREF

Figure 43. Soft Start Timing Diagram

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