Replacing relays with a 3 phase isolator MOSFET driver

March 09, 2017 // By Christoph Hammerschmidt
With the A6862, Allegro Microsystems Europe has introduced an n-channel MOSFET driver IC that can isolate a three-phase load by directly driving the isolation MOSFET, separately phase by phase. The device is designed for safety-relevant automotive systems that need to fulfill the ASIL requirements. Examples are electronic power steering, applications with three-phase relay drivers and electric brakes.

In safety-critical applications, motor isolation is a requirement which in most cases is met by discrete circuits or mechanical relays. Allegro’s A 2-SIL products offer a beneficial alternative and ease ASIL certification. The A6862 3-phase isolating driver can replace relay-controlled motor cut-off in safety-critical systems. Likewise, it can be used as reverse polarity protection and as battery separating switch.

The A6862 has three independent floating gate driver ports which enables the power MOSFETS to retain in the on- or off-state across the entire supply voltage range as well as under high phase voltage gradients. Representing The third generation of isolating drivers from Allegro, the A6862 is now equipped with additional single-input control mode, two independent enabling inputs to switch the device to energy saving mode and additional gate-source protection. The chip comes in a 16-pin TSSOP package with Exposed Pad for better heat removal.

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