User Manual
21
Revision 1.2
2018-09-23
EVAL-M1-36-84A User Manual
iMOTION
™
Modular Application Design Kit
Schematics and Layout
6.3
Current Measurement and Over Current Circuit
The resistors RS1 to RS3 are purposed to generate a voltage proportional to the emitter current. These voltages
are available at 20 pin interface connector to give feedback to the controller. In combination with resistors R70
to R72 they are used to generate common current signal V_TRIP for all three phases. V_TRIP is always on
highest level of all three phase current. This signal is used to generate gate-kill signal I_TRIP.
Figure 13 is the over current circuitry shown. Capacitor C77 and resistor R81 are filtering voltage spikes and
noise on V_TRIP to avoid incident turn off.
The comparator threshold can be set through the voltage divider provided by resistors R82 and R83. By default
for emitter-shunt trip, R7 is 1k
Ω
. In single shunt application R7 needs to be changed to 3.48k
Ω
.
Figure 13
Over current protection circuit on the EVAL-M1-36-84A evaluation board
C77
470pf
C78
0.1uf
R83
2.00k, 1%
R82
31.0k
C79
0.01uf
R81
1k
R84
4.7K
3
2
1
8
4
U5A
Comment: LM393A
+3.3V
VCC
+3.3V
1
TP15
ITRIP
C114
0.1uf
V Trip
1
TP16
V_TRIP
ITRIP
R82:
For single shunt use 10k
For leg shunts use 31k
5
6
7
U5B
Comment: LM393A
1
TP21
Par1
+3.3V
R96
4.7k
R97
4.7k
GATEKILL level set at:
2k/33k * 3.3V = 0.2V
0.2V/0.5Ohms * 3 = 1.2A