Si875x Isolated FET Drivers​​

Si8751/52 FET driver offer a simple way to replace solid-state relays (SSRs) or electromechanical relays (EMRs). Si875x devices combine robust CMOS isolation technology with a FET driver to form a complete, isolated switch. Versatile input options provide either digital CMOS pin control (Si8751) or diode emulation (Si8752) to best fit the application. Flexible outputs support driving AC or DC load configurations, and the self-contained device generates its own gate drive output voltage, reducing cost, size, and complexity. Si875x devices eliminate the need for bulky mechanical relays and allow self-selection for FET switches, so the design can be completely optimized for the application’s power, cost, and performance requirements. Unlike traditional SSRs, which integrate optocoupler-style LED inputs and limit the operating temperature range of the solution, Si875x drivers can support full industrial and automotive temperature ranges with increased stability and longer lifetime.

The Si875x drives FET gates with a nominal 10.3 V using as low as 1 mA input current, and its 2.5 kVrms isolation rating forms the basis for full certification to UL, CSA, VDE, and CQC. A unique power optimization option delivers maximum turn on current for fast speed, then lowers to static holding current once the optional external cap is discharged. Input side voltages are flexible from 2.25 V to 5.5 V and support seamless connection to low-power controllers. Si875x devices provide a clamping to prevent unintended turn on of the external FET when a high dV/dt is present on the FET’s drain.

Fast turn-off time
35 µs
Flexible input
digital or opto-emulator

Common Specs

  • Digital CMOS or diode emulation control inputs
  • 10.3 V gate drive output with <100 µs turn-on time
  • Internally-generated secondary side power supply
  • Miller clamp cap support for reducing inductive chatter
  • DC or AC load switching support
  • Drives user-selected external FETs
  • 2.5 kVrms isolation rating
  • UL, CSA, VDE, and CQC certifications (pending)
  • Industrial -40 to +105°C or Automotive -40 to 125 °C temperature ranges
  • ROHS-compliant SOIC-8 Package


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Part Number Isolation Rating (kVrms) Input Type Peak Output Current Max Propagation Delay (µs) Driver Supply Range (V) Package Type AEC-Q100 Input Supply (V) Driver Supply Feature Temperature Range (°C) 10 Kv Surge Overlap Protection and Dead Time Control

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