LD7750E 데이터 시트보기 (PDF) - Unspecified

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LD7750E

High Voltage Green-Mode PWM Controller with Over Temperature Protection

Unspecified 

VOTP

OTP Release

1.05V

0.95V

OTP

t

VCC

UVLO(on)

UVLO(off)

t

AC input Voltage

LD7750E

Therefore, the MOSFET should be always pulled-low to

persist in off-state.

t

OUT

Switching

Switching Non-Switching

t

Fig. 19

Pull-Low Resistor on the Gate Pin of

MOSFET

An anti-floating resistor is built in with the OUT pin to

prevent the output from any uncertain state. Otherwise, it

may cause the MOSFET work abnormally or mis-trigger.

However, such design won’t cover the condition of

disconnection between the OUT pin and the gate terminal

for the MOSFET. Thus it is still strongly recommended

to have a resistor connected at the MOSFET gate

terminal (as shown in Fig. 20) to provide extra protection

for fault conditions.

This external pull-low resistor is to prevent the MOSFET

from being damaged during power-on when the gate

resistor RG is disconnected. In such fault condition, as

show in Fig. 21, the resistor R8 will provide a discharge

path to avoid the MOSFET from being falsely triggered by

the current through the gate-to-drain capacitor CGD.

Fig. 20

i = Cgd ⋅ dVbulk

dt

Fig. 21

Leadtrend Technology Corporation

LD7750E-DS-00 February 2012

13

www.leadtrend.com.tw

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