Motor isolator chip aims at ASIL in cars

Motor isolation for Automotive Safety Integrity Level (ASIL) requirements can be met without electromechanical relays, claimed Allegro MicroSystems.

To do it, it has introduced the A6861 for safety-critical automotive applications where motor isolation is an essential requirement – in electronic power steering and electric braking, for example.

All the chip needs is three power mosfets, and a few passives.

“This product range is designed to help customers to achieve ASIL-D certification with the highest ASIL rating possible”, said Allegro marketing director Steve Lutz. “Our A6861 is intended to replace a relay-driven motor disconnect in automotive safety-critical systems, and can also provide the drive for reverse battery protection and battery isolation.”

On board are three independent floating gate drive outputs to independently hold the mosfets ‘on’ or ‘off’ over the full 4.5-50V supply range in the presence of high phase-voltage slew rates. An integrated charge pump regulator is included to maintain 7.5V gate drive with 100kohm gate-source resistors.

With the addition of a few external components, it can also isolate the load when high load currents are present.

In typical applications the MOSFETs will be switched on within 8μs and will switch off within 1μs.

An under-voltage monitor checks that the pumped supply voltage is high enough to mosfets conduct properly.

Packaging is 16 lead thermal pad TSSOP.

As the three channels are separate, the chip and its mosfets can also control three separate loads.

from News http://ift.tt/1jXATKu

via Yuichun