User Manual
20
Revision 1.0
2019-07-25
EVAL-M1-36-44A 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 C32 and resistor R39 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 R36 and R40. By default
for emitter-shunt trip, R40 is 3.2k
.
Figure 13
Over current protection circuit on the EVAL-M1-36-44A evaluation board
C32
470pf
C30
0.1uf
R40
3.2k,1%
R36
31.0k
C33
0.01uf
R39
1k
R38
4.7K
3
2
1
8
4
U5A
Comment: LM393A
+3.3V
VCC
5
6
7
U5B
Comment: LM393A
+3.3V
GATEKILL level set at:
2k/33k * 3.3V = 0.2V
0.2V/0.5Ohms * 3 = 1.2A
1
TP17
ITRIP
C31
0.1uf
V Trip
1
TP16
V_TRIP
ITRIP
R36:
For single shunt use 10k
For leg shunts use 31k
1
TP18
Par1
+3.3V
R37
4.7k
R41
4.7k