Automotive Three-Phase Isolator MOSFET Driver Replaces Mechanical Relays, Discretes

By controlling the in-phase isolation MOSFETs, Allegro MicroSystems’ A6861 N-channel power MOSFET driver can isolate a three-phase load. The driver IC is intended for automotive systems that must meet Automotive Safety Integrity Level (ASIL) requirements. Specifically, it can replace a relay-driven motor disconnect in automotive electronic power steering (EPS) or other safety-critical systems. It also provides the drive for reverse battery protection and battery isolation. Three independent floating gate-drive outputs maintain the power MOSFETs in the on or off state over the full supply range in the presence of high phase-voltage slew rates. An integrated charge-pump regulator supplies the above battery supply voltage needed to keep the power MOSFETs in the on state continuously when the phase voltage equals the battery voltage. The pump maintains sufficient gate drive (>7.5 V) for battery voltages down to 3.5 V with 100-kΩ gate-source resistors. A logic-level control input enables independent control of three gate drives. The A6861KLPTR-T comes in a 16-lead TSSOP package with an exposed pad for enhanced thermal performance.

ALLEGRO MICROSYSTEMS LLC