ACPL-798J Datasheet, PDF (1/17 Pages) AVAGO TECHNOLOGIES LIMITED – Optically Isolated Sigma-Delta Modulator with LVDS Interface

ACPL-798J
Optically Isolated Sigma-Delta Modulator with LVDS Interface
Data Sheet
Lead (Pb) Free
RoHS 6 fully
compliant
RoHS 6 fully compliant options available;
-xxxE denotes a lead-free product
Description
The ACPL-798J is a 1-bit, second-order sigma-delta (Σ-∆)
modulator that oversamples an analog input signal into
a highspeed data stream with galvanic isolation based
on optical coupling technology. The ACPL-798J operates
from a 5 V power supply with dynamic range of 82 dB with
an appropriate digital filter. The differential inputs of ±200
mV (full scale ±320 mV) are ideal for direct connection to
shunt resistors or other low-level signal sources in applica-
tions 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 25 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 filter. The
ACPL-798J comes with an LVDS interface on both clock
inputs and data outputs for better signal integrity.
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-798J
provides reliable double protection and high working in-
sulation voltage, which is suitable for fail-safe designs.
This outstanding isolation performance is superior to al-
ternatives including devices based on capacitive or mag-
netic-coupling with DTI in micro-meter range. Offered in
an SO-16 package, the isolated ADC delivers the reliability,
small size, superior isolation and over-temperature perfor-
mance motor drive designers need to accurately measure
current at much lower price compared to traditional
current transducers.
Features
• Up to 25 MHz external clock input range
• LVDS clock and data interface.
• 1-bit, second-order sigma-delta modulator
• 16 bits resolution no missing codes (12 bits ENOB)
• 75dB Typical SNDR
• 3.5mV/°C maximum offset drift
• ±1% maximum gain error
• ±200 mV linear range with single 5 V supply
• –40°C to +105°C operating temperature range
• SO-16 package
• 25 kV/µs common-mode transient immunity
• Safety and regulatory approval (pending):
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 replacement
Functional Block Diagram
V_DD1
V_IN +
Σ−∆
MODULATOR/
LED
DRIVER
DECODER
V _IN –
ENCODER
SHIELD
VDD2
MDAT+
MDAT-
VREF
GND1
Figure 1.
CLOCK
DETECTOR
SHIELD
LED
DRIVER
ACPL-798J
MCLKIN+
MCLKIN-
GND2
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.