ACPL-796J
Optically Isolated Sigma-Delta Modulator
Data Sheet
Description
The ACPL-796J is a 1-bit, second-order sigma-delta ()
modulator converts an analog input signal into a high-
speed data stream with galvanic isolation based on optical
coupling technology. The ACPL-796J operates from a 5 V
power supply with dynamic range of 80 dB with an appro-
priate digital lter. The di erential inputs of ±200 mV (full
scale ±320 mV) are ideal for direct connection to shunt
resistors or other low-level signal sources in applications
such as motor phase current measurement.
The analog input is continuously sampled by means of
sigma-delta over-sampling using external clock, coupled
across the isolation barrier, which allows synchronous
operation with any digital controller. The signal infor-
mation is contained in the modulator data, as a density
of ones with data rate up to 20 MHz, and the data are
encoded and transmitted across the isolation boundary
where they are recovered and decoded into high-speed
data stream of digital ones and zeros. The original signal
information can be reconstructed with a digital lter. The
serial interface has a wide supply range of 3 V to 5.5 V.
Combined with superior optical coupling technology,
the modulator delivers high noise margins and excellent
immunity against isolation-mode transients. With 0.5 mm
minimum distance through insulation (DTI), the ACPL-796J
provides reliable double protection and high working
insulation voltage, which is suitable for fail-safe designs.
This outstanding isolation performance is superior to
alternatives including devices based on capacitive- or
magnetic-coupling with DTI in micro-meter range. O ered
in an SO-16 package, the isolated ADC delivers the reli-
ability, small size, superior isolation and over-temperature
performance motor drive designers need to accurately
measure current at much lower price compared to tradi-
tional current transducers.
The internal clock version modulators, HCPL-7860 (DIP-8/
gull wing surface mount package) and HCPL-786J (SO-16
package), are also available.
Features
5 MHz to 20 MHz external clock input range
1-bit, second-order sigma-delta modulator
16 bits resolution no missing codes (12 bits ENOB)
74 dB minimum SNR
3.5 V/°C maximum o set drift
±1% maximum gain error
Internal reference voltage
±200 mV linear range with single 5 V supply
3 V to 5.5 V wide supply range for digital interface
–40°C to +105°C operating temperature range
SO-16 package
25 kV/s common-mode transient immunity
Safety and regulatory approval:
IEC/EN/DIN EN 60747-5-5: 1414 Vpeak working
insulation voltage
UL 1577: 5000 Vrms/1min double protection rating
CSA: Component Acceptance Notice #5
Applications
Motor phase and rail current sensing
Power inverter current and voltage sensing
Industrial process control
Data acquisition systems
General purpose current and voltage sensing
Traditional current transducer replacements
Functional Block Diagram
Figure 1.
Σ−Δ
MODULATOR/
ENCODER
V
IN
SHIELD
V
IN
BUF
V
REF
LED
DRIVER
CLOCK
DETECTOR
SHIELD
DECODER
LED
DRIVER
MCLKIN
MDAT
V
DD2
GND2GND1
V
DD1
ACPL-796J
+
−
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. The components
featured in this datasheet are not to be used in military or aerospace applications or environments.
