HCPL-788J Datasheet, PDF (14/20 Pages) AVAGO TECHNOLOGIES LIMITED – Isolation Amplifier with Short Circuit and Overload Detection SO-16 Package

R2
39 Ω
INPUT
+
CURRENT _RSHUNT
0.02 Ω
R1
.01 μF
C3
0.1 μF
ISOLATED +5 V
C1
0.1 μF
1
C2
2
V_IN+
V_IN-
HCPL-788J
GND₂ 16
V_DD2 15
3 C_H
FAULT 14
4 C_L
ABSVAL 13
5 V_DD1
V_OUT 12
6 V_LED1+
V_REF 11
7 V_DD1
V_DD2 10
8 GND₁
GND₂ 9
C6
0.1 μF
R3 4.7 kΩ
μC
TO OTHER
PHASE OUTPUTS
C8 C4 C7 C5
A/D
V_REF
GND
Figure 25. Recommended applications circuit.
+5 V
C5 = C7 = C8 = 470 pF
C4 = 0.1 μF
HV+
GATE DRIVE
CIRCUIT
R4
+
FLOATING
POWER
SUPPLY
–
MOTOR
+ ^R1 +
R_SENSE
R2
39 Ω
D1
5.1 V
HV-
Figure 26. Recommended supply and sense resistor connections.
C1
0.1 μF
C2
0.01 μF
5 V_DD1
HCPL-788J
GND₂ 16
1 V_IN+
V_DD2 15
2 V_IN-
FAULT 14
8 GND₁
ABSVAL 13
7 V_DD1
V_OUT 12
3 C_H
V_REF 11
4 C_L
V_DD2 10
6 V_LED+
GND₂ 9
Analog Interfacing
Power Supplies and Bypassing
The recommended supply connections are shown in
Figure 26. A floating power supply (which in many ap-
plications could be the same supply that is used to drive
the high-side power transistor) is regulated to 5 V us-
ing a simple zener diode (D1); the value of resistor R4
should be chosen to supply sufficient current from the
existing floating supply. The voltage from the current
sensing resistor (Rsense) is applied to the input of the
HCPL-788J through an RC anti-aliasing filter (R2 and C2).
Although the application circuit is relatively simple, a few
recommendations should be followed to ensure optimal
performance.
The power supply for the HCPL-788J is most often ob-
tained from the same supply used to power the power
transistor gate drive circuit. If a dedicated supply is re-
quired, in many cases it is possible to add an additional
winding on an existing transformer. Otherwise, some
sort of simple isolated supply can be used, such as a line
powered transformer or a high-frequency DC-DC con-
verter.
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