±50mV Optically Isolated Sigma-Delta Modulator

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The ACPL-C799 is a 1-bit, second-order sigma-delta (Σ-Δ) modulator that converts an analog input signal into a high-speed data stream with galvanic isolation based on optical coupling technology. The ACPL-C799 operates from a 5V power supply with dynamic range of 77 dB with an appropriate digital filter. The differential inputs of ±50 mV (full scale ±80 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 a means of sigma-delta over-sampling using an on-board clock. The signal information is contained in the modulator data, as a density of ones with data rate of 10 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 serial interface for data and clock 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-C799 provides reliable reinforced insulation 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. Offered in a Stretched SO-8 (SSO-8) package, the isolated ADC delivers the reliability, small size, superior isolation and over-temperature performance motor drive designers need to accurately measure current at much lower price compared to traditional current transducers.


  • 10 MHz internal clock
  • 1-bit, second-order sigma-delta modulator
  • 16 bits resolution no missing codes (12 bits ENOB)
  • 77 dB SNR typ
  • 1.3 μV/°C maximum offset drift
  • ±1% gain error
  • Internal reference voltage
  • ±50 mV linear range with single 5 V supply (±80 mV full scale)
  • 3 V to 5.5 V wide supply range for digital interface
  • –40°C to +105°C operating temperature range
  • SSO-8 package
  • 25 kVμs 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 isolation voltage
    • CSA: Component Acceptance Notice #5


  • Servo drives and motors
  • Motor phase and rail current sensing
  • Power inverter current sensing
  • Industrial Process Control
  • Data Acquisition Systems
  • General purpose current sensing
  • Traditional current transducer replacements

Lifecycle Status


Substance Compliance

  • RoHS6
    Fully Compliant
Specification Value
Lifecycle Active
Distrib. Inventory Yes
RoHS6 Compliant Y
Product Type Isolated Modulator
Package Stretched SO8
Gain Error at 25 Deg C (%) Max ±1
VDD2 (V) 3 - 5.5
CMR (min.) (V/µs) 25000.0
Vcm (V) 1000.0
UL Insulation Rating Viso (VRMS) 5000.0
IEC Maximum Working Insulation Voltage Viorm (VPEAK) 1414.0
IEC Highest Allowable Overvoltage Viotm (VPEAK) 8000
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