Sigma-delta modulator eval kits aid industrial and automotive designs

At PCIM 2018, the company showcased its isolated three-phase current/voltage sense module, with the ACPL-0873 three-channel digital filter. It also offers the isolated current/voltage sense module with Sinc3 Filter using Xilinx’s Spartan FPGA. For automotive battery management systems, there is an isolated 500A current sense module.

The evaluation kits feature programmable digital filters, sampling time synchronisation, fast over-range detection, offset calibration and programmable input configuration.

A Window-based GUI allows engineers to configure the digital filter and read the real-time current or voltage measurements from the evaluation kit to the computer via a USB interface.

Chun Keong Tee, product manager, Broadcom, explained that the optically isolated sigma-delta modulator converts an analogue input signal into a high-speed data stream with galvanic isolation based on optical coupling technology. It is an alternative to capacitive or magnetic-coupling-based designs and is claimed to deliver high noise margins and immunity against isolation-mode transients for reinforces insulation and high working insulation voltage.

The modulators are offered in SSO-8 and SO-16 packages for current measurement at a lower price point than traditional current transducers.

The evaluation kits are available with a choice of isolated sigma-delta modulators. The ACPL-C799/C799T is a ±50mV model with 10MHz internal clock, the ACPL-C740 operates at ±200mV and has a 20MHz internal clock, the ACPL-796J is a ±200mV version with an external clock and the ACPL-798J is ±200mV rated with an LVDS interface and an external clock. A ±50mV version, the ACPL-736J/ACPL-738J with an external clock is currently under development.