Reinforced Isolated Delta-Sigma Modulator for Voltage SensingFebruary 05, 2020 by Paul Shepard
The AMC1336 from Texas Instruments 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 8000 VPEAK according to the DIN VDE V 0884-11 and UL1577 standards.
Used in conjunction with isolated power supplies, this isolated modulator separates parts of the system that operate on different common-mode voltage levels and protects lower-voltage parts from damage.
The unique wide, bipolar ±1-V input voltage range of the AMC1336 and its high input resistance support direct connection of the device to resistive dividers in high-voltage applications. When used with a digital filter (for instance, as integrated in the TMS320F28004x, TMS320F2807x or TMS320F2837x microcontroller families) to decimate the output bitstream, the device can achieve 16 bits of resolution with a dynamic range of 87 dB at a data rate of 82 kSPS.
On the high-side, the AMC1336 is supplied by a 3.3-V or 5-V power supply. The isolated digital interface operates from a 3.0-V, 3.3-V or 5-V power supply.
The AMC1336 performance is specified over the extended industrial temperature range of –40°C to +125°C.
Summary of Features
- Input structure optimized for voltage measurements:
- Input voltage range: ±1V
- Input resistance: 1.5GΩ (typ)
- Excellent dc performance:
- Offset error: ±0.5mV (max)
- Offset drift: ±4µV/°C (max)
- Gain error: ±0.25% (max)
- Gain drift: ±40ppm/°C (max)
- Transient immunity: 115kV/µs (typ)
- Missing high-side supply detection
- Safety-related certifications:
- 8000-VPEAK reinforced isolation per DIN VDE V 0884-11: 2017-01
- 5700-VRMS isolation for 1 minute per UL1577
- IEC 62368-1 end equipment standard