Broadcom Inc. Optically Isolated Sigma-Delta Modulator ACPL-C797

The ACPL-C797 is a 1-bit, second-order sigma-delta modulator that converts an analog input signal into a high-speed data stream through integration of galvanic isolation based on optical coupling technology. The ACPL-C797 uses a 5 V power supply with dynamic range of 80 dB and 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 applications such as motor phase current measurement. The analog input is continuously measured by the sigma-delta modulator by 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. Data is then encoded and transmitted across the isolation boundary where it is 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 C797 provides reliable reinforced insulation and high working insulation voltage, which is suitable for fail-safe designs. This isolation performance is superior to alternatives including devices based on capacitive- or magnetic-coupling with DTI in micro-meter range. Offered in a SO-16 package, the isolated ADC delivers the reliability, small size, superior isolation and over-temperature performance motor drive designers need to accurately measure current. This design alternative delivers a lower price when compared to traditional current transducers. An external clock version modulator ACPL-796J (SO-16 package) is also available. Features 10 MHz internal clock 1-bit, second-order sigma-delta modulator 16 bits resolution no missing codes (12 bits ENOB) TBD dB minimum SNR 3.5 µV/°C maximum offset drift ±1% maximum gain error Internal reference voltage ±200 mV linear range with single 5 V supply (±320 mV full scale) 3 V to 5.5 V wide supply range for digital interface –40°C to +105°C operating temperature range Stretched SO-8 package 25 kV/µs common-mode transient immunity Safety and regulatory Approval (pending): UL 1577 (5000 Vrms/1 min.) CSA IEC/EN/DIN EN 60747-5-5 Options available are : 000E: Lead Free Option 060E: IEC/EN/DIN EN 60747-5-5 Option 500E: Tape and Reel Packaging Option 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