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Isolated chips for precise current, voltage sensing in power systems

Isolated chips for precise current, voltage sensing in power systems

New Products |
By Nick Flaherty



The new Si89xx family, says the company, provides flexible voltage, current, output and package options to help developers reduce BOM cost and shrink board space for a wide 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.

To maximize efficiency and respond quickly to faults or changes in load in power control systems, system controllers require current and voltage information from high-voltage rails. The new devices are based on the company’s third-generation isolation technology, which, says the company, keeps controllers safe across wide temperature variations with 1414 V working voltage and 13 kV bipolar surge, exceeding stringent industry requirements.

“Our first and second generation mixed-signal isolation technologies have driven the strong market success of our digital isolation products over the past decade, and our third-generation technology used in the new Si89xx devices raises the bar even higher,” says Brian Mirkin, Vice President and General Manager of Silicon Labs’ power products. “Our isolation products continue to replace traditional optocouplers and outperform competing digital isolators, enabling higher surge performance, reliability, integration and best-in-class safety for system designs requiring protection from high voltages.”

The Si89xx family includes four product categories:

  • Si892x isolated analog amplifiers optimized for shunt-current sensing
  • Si8931/2 isolated analog amplifiers optimized for general-purpose voltage sensing
  • Si8935/6/7 isolated DSM devices optimized for voltage sensing—an industry first
  • Si8941/6/7 isolated DSM devices optimized for shunt-current sensing

The Si89xx devices feature 75 kV/µs immunity to fast transients and support a fail-safe indication to the host controller if the high-side supply voltage is not detected. The devices provide typical offset error as low as ±40 µV and ±0.1% gain error, enabling precise measurements. Typical offset drift and gain drift are as low as ±0.15 µV/°C and –6 ppm/°C, respectively.

Typical signal-to-noise ratio (SNR) is up to 90 dB. A unique low-power mode automatically reduces current draw on one side of the isolation barrier to approximately 1 mA whenever voltage is removed from the other side, enabling a controller to manage power with a simple field-effect transistor (FET).

The devices are offered in current or voltage-optimized versions with single-ended, differential, or DSM output, and with ±62.5 mV, ±250 mV, or 2.5 V input ranges. Additional options include a stretched wide-body SOIC-8 package to support 5 kVrms isolation and 9 mm creepage/clearance and a compact narrow-body SOIC-8 to support 2.5 kVrms isolation.

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, with production quantities of all Si89xx devices planned for Q3.

Silicon Labs

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