LD7576GS datasheet(14/22 Pages) LEADTREND

14 / 22 page

LD7576/76H/76J/76K

Leadtrend Technology Corporation

www.leadtrend.com.tw

LD7576-DS-04a

December 2009

Fig. 20

Pull-Low Resistor on the Gate Pin of

MOSFET

The LD7576X series is internally equipped with an

anti-floating resistor on the OUT pin to protect the output

from abnormal operation or false triggering of MOSFET.

Even so, we still recommend adding an external one on

the MOSFET gate terminal to provide more protection in

case of disconnection of gate resistor RG during power-on.

In such single-fault condition, as show in figure 22, the

resistor R8 can provide a discharge path to avoid the

MOSFET from being falsely-triggered by the current

through the gate-to-drain capacitor CGD. Therefore, the

MOSFET is always pulled low and placed in the off-state

even if the gate resistor is disconnected or opened in any

case.

Fig. 21

Cgd

bulk

⋅

Fig. 22

Protection Resistor on the Hi-V Path

In some other Hi-V process and design, there may be a

parasitic SCR caused around HV pin, Vcc and GND.

shown in figure 23, a small negative spike on the HV pin

may trigger this parasitic SCR and cause latchup between

Vcc and GND.

It will intend to damage the chip because

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