AMC1304x Delta-Sigma Modulators

By Texas Instruments 44

AMC1304x Delta-Sigma Modulators

Texas Instruments’ AMC1304x is a precision delta-sigma (ΔΣ) modulator with the output separated from the input circuitry by a capacitive double-isolation barrier that is highly resistant to magnetic interference. This barrier is certified to provide reinforced isolation of up to 7,000 VPEAK according to the DIN V VDE V 0884-10, UL1577, and CSA standards. Used in conjunction with isolated power supplies, the device prevents noise currents on a high common-mode voltage line from entering the local-system ground and interfering with or damaging low voltage circuitry.

The input of the AMC1304x is optimized for direct connection to shunt resistors or other low voltage-level signal sources. The unique low input voltage range of the ±50 mV device allows significant reduction of the power dissipation through the shunt while supporting excellent AC and DC performance. By using an appropriate digital filter (that is, as integrated on the TMS320F2807x or TMS320F2837x families) to decimate the bit stream, the device can achieve 16 bits of resolution with a dynamic range of 81 dB (13.2 ENOB) at a data rate of 78 kSPS.

On the high-side, the modulator is supplied by an integrated low-dropout (LDO) regulator that allows an unregulated input voltage between 4 V and 18 V (LDOIN). The isolated digital interface operates from a 3.3 V or 5 V power supply (DVDD).

Features
  • Pin-compatible family optimized for shunt-resistor-based current measurements:
    • ±50 mV or ±250 mV input-voltage ranges
    • CMOS or LVDS digital interface options
  • Excellent DC performance, supporting high-precision sensing on system level:
    • Offset error: ±50 µV or ±100 µV (max.)
    • Offset drift: 1.3 µV/°C (max.)
    • Gain error: ±0.2% or ±0.3% (max.)
    • Gain drift: ±40 ppm/°C (max.)
  • High electromagnetic-field immunity
  • Certified isolation barrier:
    • Reinforced isolation rating
    • DIN VDE V 0884-10, UL1577, and CSA approved
    • Isolation voltages: 7,000 VPEAK, 10,000 VSURGE
    • Working voltages: 1,500 VDC, 1,000 VAC RMS
    • Transient immunity: 15 kV/µs (min.)
  • External 5 MHz to 20 MHz clock input for easier system-level synchronization
  • On-chip 18 V LDO regulator
  • Fully specified over the extended industrial temperature range

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