Isolated ICs exhibit low temperature drift for green energy

Isolated analogue amplifiers, voltage sensors and delta-sigma modulator (DSM) devices released by Silicon Labs, are based on the third generation isolation technology, designed to provide accurate current and voltage measurement with very low drift across temperature.

The Si89xx family provides flexible voltage, current, output and package options to help developers reduce the bill of materials and shrink board space for a range of industrial and green-energy applications including electric vehicle (EV) battery management and charging systems, dc/dc converters, and motor, solar and wind turbine inverters.

Precise current and voltage measurement is essential for accurate operation of power control systems. To maximise efficiency and respond quickly to faults or changes in load, system controllers require current and voltage information from high-voltage rails. Silicon Labs’ third-generation isolation technology keeps controllers safe across wide temperature variations with 1414V working voltage and 13kV bipolar surge, exceeding stringent industry requirements, reports the company.

The Si89xx family consists of the Si892x, a group of isolated analogue amplifiers optimised for shunt-current sensing. The other three groups within the family are the Si8931 and Si8932 isolated analogue amplifiers for general-purpose voltage sensing, the Si8935, Si8936 and Si8937 isolated DSM devices for voltage sensing. This is an industry first, claims Silicon Labs. Finally, there is the Si8941, Si8946 and Si8947 isolated DSM devices for shunt-current sensing.

Automotive battery and motor or photovoltaic (PV) inverter systems require reliable current monitoring with robust noise immunity. The Si89xx devices provide up to three times higher common-mode transient immunity (CMTI) than competing products. The devices’ 75kV/micro seconds immunity to fast transients ensures reliable and accurate current readings in demanding industrial applications. The Si89xx family also supports a fail-safe indication to the host controller if the high-side supply voltage is not detected.

The Si89xx devices provide typical offset error as low as ±40 microV and ±0.1 per cent gain error, enabling precise measurements. Typical offset drift as low as ±0.15 microV/˚ degrees C and typical gain drift as low as –6 ppm/ degrees C ensure exceptional accuracy across temperature, claims Silicon Labs. The devices offer the industry’s highest typical signal-to-noise ratio (SNR)—up to 90dB. A low-power mode automatically reduces current draw on one side of the isolation barrier to approximately 1mA whenever voltage is removed from the other side, enabling a controller to manage power with a simple FET.

Advanced samples of Si892x/3x/4x devices in wide-body SOIC-8 packages are available now, and advanced samples of the devices in narrow-body SOIC-8 packages are planned to be available in Q2. Production quantities of all Si89xx devices are planned for Q3.

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