Application Information
1. FAULT-OUT DURATION TIME (TDUR)
1) Two modes in Fault-Out Duration.
- OCP mode
Fault-Out Duration operates after TOCP.
- SCP mode
If Vpin8 is over 6.5V, Fault-Out Duration will operate after TSCP.
2) TDUR (It can be adjusted by external capacitor (CDUR) is
TDUR = CDUR ⁄ 55µA × (5V – 1.4V)
= 2.7nF ⁄ 55µA × (5V – 1.4V)
= 176µs
2. SLOW TURN-OFF (TSLOW)
Internal Circuit
Low
Low
Q1
5
Q2
Q3
Vlink
L
O
A
D
FAN8800 (KA3162)
1) When SCP (Short Circuit Protection) is operated, Q3 turns on and Q2 turns on.
2) In the upper condition, Q2 flows the constant current of 35mA.
3) The capacitance of IGBT as the load is discharging by 35mA, that is Slow Turn-off.
4) Slow Turn-off time is
TSLOW = CIGBT ⁄ 35mA × (V5max – V5min)
= 4.7nF ⁄ 35mA × (15V – 1V)
= 1.9µs
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