Datasheet

V
IN+
V
IN-
V
CC1
GND1
RESET
FAULT
µC
ISO5500
1
2
3
6
5
4
8
7
NC
GND1
V
IN+
V
IN-
V
CC1
GND1
RESET
FAULT
µC
1
2
3
6
5
4
8
7
NC
GND1
ISO5500
V
IN+
V
IN-
V
CC1
GND1
RESET
FAULT
µC
ISO5500
1
2
3
6
5
4
8
7
NC
GND1
V
IN+
V
IN-
V
CC1
GND1
RESET
FAULT
µC
ISO5500
1
2
3
6
5
4
8
7
NC
GND1
ISO5500
www.ti.com SLLSE64C –SEPTEMBER 2011–REVISED JUNE 2013
Figure 66. Auto Reset for Non-inverting and Inverting Input Configuration
RESETTING FOLLOWING A FAULT CONDITION
To resume normal switching operation following a fault condition (FAULT output low), the gate control signal
must be driven into a 'gate low' state before asserting RESET low. This can be accomplished with a micro-
controller, or an additional logic gate that synchronizes the RESET signal with the appropriate input signal.
Figure 67. Auto Reset with Prior Gate-low Assertion for Non-inverting and Inverting Input Configuration
DESAT PIN PROTECTION
Switching inductive loads causes large instantaneous forward voltage transients across the freewheeling diodes
of IGBTs. These transients result in large negative voltage spikes on the DESAT pin which draw substantial
current out of the device. To limit this current below damaging levels, a 100 Ω to 1 kΩ resistor is connected in
series with the DESAT diode. The added resistance neither alters the DESAT threshold nor the DESAT blanking
time.
Further protection is possible through an optional Schottky diode, whose low forward voltage assures clamping of
the DESAT input to V
E
potential at low voltage levels.
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