ACPL-C78A, ACPL-C780, ACPL-C784
Miniature Isolation Ampliers
Data Sheet
CAUTION: It is advised that normal static precautions be taken in handling and assembly
of this component to prevent damage and/or degradation which may be induced by ESD.
NOTE: A 0.1 μF bypass capacitor must be connected between pins 1 and
4 and between pins 5 and 8.
Description
The ACPL-C78A/C780/C784 family of isolation ampli-
ers is designed for current sensing in electronic motor
drives. In a typical implementation, motor currents ow
through an external resistor and the resulting analog
voltage drop is sensed by the ACPL-C78A/C780/C784. A
dierential output voltage is created on the other side of
the ACPL-C78A/C780/C784 optical isolation barrier. This
dierential output voltage is proportional to the motor
current and can be converted to a single-ended signal
by using an op-amp as shown in the recommended ap-
plication circuit. Since common-mode voltage swings
of several hundred volts in tens of nanoseconds are
common in modern switching inverter motor drives, the
ACPL-C78A/C780/C784 is designed to ignore very high
common-mode transient slew rates (of at least 10 kV/μs).
The high CMR capability of the ACPL-C78A/C780/C784
isolation amplier provides the precision and stability
needed to accurately monitor motor current in high noise
motor control environments, providing for smoother
control (less “torque ripple”) in various types of motor
control applications.
The product can also be used for general analog signal
isolation applications requiring high accuracy, stability,
and linearity under similarly severe noise conditions. For
general applications, we recommend the ACPL-C780 (gain
tolerance of ±3%) and the ACPL-C784 (gain tolerance of
±5%). For precision applications Avago Technologies oers
the ACPL-C78A with part-to-part gain tolerance of ±1%.
The ACPL-C78A/C780/C784 utilizes sigma-delta (∑-∆) an-
alog-to-digital converter technology, chopper stabilized
ampliers, and a fully dierential circuit topology.
Together, these features deliver unequaled isolation-
mode noise rejection, as well as excellent oset and gain
accuracy and stability over time and temperature. This
performance is delivered in a compact, auto-insertable,
Stretched SO-8 (SSO-8) package that meets worldwide
regulatory safety standards.
Features
• 15 kV/μs Common-Mode Rejection at V
CM
= 1000 V
• Compact, Auto-Insertable Stretched SO-8 Package
• 0.00025 V/V/°C Gain Drift vs. Temperature
• 0.3 mV Input Oset Voltage
• 100 kHz Bandwidth
• 0.004% Nonlinearity
• Worldwide Safety Approval: UL 1577 (5000 Vrms/1 min.),
CSA and IEC/EN/DIN EN 60747-5-5
• Advanced Sigma-Delta (∑-∆) A/D Converter Technology
• Fully Dierential Amplier
Applications
• Motor Phase and Rail Current Sensing
• Inverter Current Sensing
• DC bus voltage sensing
• General Purpose Current Sensing and Monitoring
• General Purpose Analog Signal Isolation
Functional Diagram
1
2
3
4
8
7
6
5
I
DD1
V
DD1
V
IN+
V
IN-
GND1
I
DD2
V
DD2
V
OUT+
V
OUT-
GND2
+
-
+
-
SHIELD
