ld7577j Leadtrend Technology, ld7577j Datasheet - Page 14

• Manufacturer Part Number: ld7577j
• Description: High Voltage Green-mode Pwm Controller With Brown-out Protection
• Manufacturer: Leadtrend Technology

Pull-Low Resistor on the Gate Pin of
MOSFET
An anti-floating resistor is implemented in the OUT pin to
prevent any uncertain output, which may cause MOSFET
to work abnormally or false trigger on. However, such
design may not apply in all the disconnection of gate
resistor R
resistor connected at the MOSFET gate terminal (as
shown in figure 22) to provide extra protection in fault
conditions.
This external pull-low resistor is to prevent the MOSFET
from being damaged during power-on when the gate
resistor is disconnected. In such single-fault condition,
as shown in figure 23, the resistor R8 can provide a
discharge path to avoid the MOSFET from being
false-triggered by the coupling through the gate-to-drain
capacitor C
pulled low to maintain in a off-state no matter the gate
resistor is disconnected or opened in any case.
Leadtrend Technology Corporation
LD7577J-DS-00b July 2009
UVLO- OFF
UVLO - ON
Voltage
1.05V
Line
V
4.16
3.92
Vcc
OUT
BNO
G
. It is still strongly recommended to have a
GD
AC OK area
Switching
. Therefore, the MOSFET gate should be
Fig.21
Non- Switching
www.leadtrend.com.tw
AC OK area
Switching
t
t
t
t
14
Fig. 22
Fig. 23
i
=
LD7577J
Cgd
⋅
dV
dt
bulk