1-213

Fault Circuit Operation

A typical desaturation protected

IGBT gate drive application

circuit using the HCPL-3160 is

shown in Figure 1. The IGBT

collector to emitter voltage

exceeds the internal reference

voltage of 7 V the IGBT gate is

“softly” turned-off by M2 to

prevent large di/dt generation.

The LED2 driver is also activated,

which drives the internal

feedback LED2 and notifies the

controller of the IGBT fault by

bringing the FAULT output low.

The FAULT output remains

low until RESET is brought low.

(Note if a separate reset line

is not required, RESET can be

connected to Vin on the circuit

board. In this case, the FAULT

output will be reset on the next

PWM cycle that Vin goes low.)

The FAULT output is an open

collector which allows the FAULT

outputs from all the HCPL-3160s

in a drive to be connected

together in a “wired OR” forming

Q R

Q S

SHIELD

GND

FAULT

RESET

ENABLE

LED1+

LED1–

GND

BUFFER IC

LED1

R Q

S Q

D

R

I

V

E

R

–

+

+

–

+

–

+

–

+

–

+

–

0.1 µF

TRIPLE

DARLINGTON

UVLO

Q1

7 V

DESAT

M2

1X

12 V/11 V

LED2

SHIELD

(OPTIONAL)

M1

33X

A3

LED2

DRIVER

DETECTOR IC

HCPL-3160

Figure 1. IGBT Gate Drive with Desaturation Protection and Fault Feedback.

a single fault bus for interfacing

with the micro-controller. The

ENABLE input can also be

connected to this fault bus. With

this connection all IGBTs in a

drive are shutdown without

micro-controller intervention

once a fault is detected on a

single IGBT.

detection circuitry for a time

period sufficient for normal IGBT

Q1 when the IGBT is off.