Galvanically Isolated Sigma-Delta Modulators to Boost Accuracy and Reliability in Industrial Applications


ByRajni Setia 0

Galvanically Isolated Sigma-Delta Modulators

STMicroelectronics has released two galvanic isolated Sigma-Delta modulators, ISOSD61 and ISOSD61L for delivering enhanced performance and reliability in motor control, electric-vehicle charging stations, solar inverters, UPS, and server and telecom power supplies, and other industrial applications. While the ISOSD61 modulator has TTL/CMOS-compatible clock-input and data-output signal levels, the ISOSD61L is compatible with Low-Voltage Differential Signaling (LVDS).

Both the ISOSD61 modulator and ISOSD61L modulator are feature 86dB Signal-to-Noise Ratio (SNR) and 16-bit analog-to-digital converter (ADC). These devices are designed to convert an analog input signal with an amplitude of up to ±320mV into a high-speed 1-bit digital data stream at up to 25Msamples/s. Isolation between the two sides is guaranteed up to 6kV maximum transient and surge isolation voltages, and up to 1.2kV maximum working voltage, under normal working conditions.

The 30kV/μs common-mode transient immunity enables these modulators to be used in motor control, electric-vehicle charging stations, solar inverters, UPS, and server and telecom power supplies. The 25MHz sampling frequency makes them suitable for very wide input signal bandwidths thereby translating into high-frequency signal-processing capability and measurement accuracy. The ADC and isolated UART peripheral functions integrated into a single chip reduces the bill of materials and increases noise immunity and reliability thereby lowering overall end-application cost.

Key Features of ISOSD61 and ISOSD61L Modulators

  • Up to 25 MHz external clock input for easier synchronization
  • ±320 mV full-scale analog input range
  • 16-bit resolution, no missing codes
  • 13-bit typical ENOB
  • 86 dB typical SNR
  • -83 dB typical THD
  • 30 kV/µs typical High Common-mode transient immunity
  • 6000 VPEAK Isolation Voltage VIOTM
  • 1200 VPEAK Working Voltage VIORM
  • –40°C to +125°C extended industrial temperature range

Get Our Weekly Newsletter!

Subscribe below to receive most popular news, articles and DIY projects from Circuit Digest


Log in or register to post Comment