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AV02-1670EN - July 27, 2016
Voltage Sensing
The ACPL-796J can also be used to isolate signals with am-
plitudes larger than its recommended input range with
the use of a resistive voltage divider at its input. The only
restrictions are that the impedance of the divider be rela-
tively small (less than 1 k) so that the input resistance
(33 k) and input bias current (0.5 A) do not a ect the
accuracy of the measurement. An input bypass capacitor
is still required, although the 39 series damping resistor
Figure 19. Schematic for three conductor shunt connection.
NON-
ISOLATED
5 V/3.3 V
FLOATING POSITIVE
SUPPLY
V
IN
+
V
IN
–
V
DD1
GND1
MCLKIN
MDAT
V
DD2
GND2
C3
0.1 PF
ISOLATION
BARRIER
GATE
DRIVE
CIRCUIT
HV+
C1
0.1 PF
D1
5.1 V
R1
ACPL-796J GND2
C4
10 PF
C5
10 PF
R
SENSE
HV–
C2a
10 nF
MOTOR
R2a 39 :
C2b
10 nF
R2b 39 :
+–
GND1
is not (the resistance of the voltage divider provides the
same function). The low-pass lter formed by the divider
resistance and the input bypass capacitor may limit the
achievable bandwidth. To obtain higher bandwidth, the
input bypass capacitor (C2) can be reduced, but it should
not be reduced much below 1000 pF to maintain adequate
input bypassing of the isolated modulator.
