12-48V, 6-phase, bidirectional DC/DC controller for dual-rail automotive
The device is a 6-phase synchronous PWM controller that performs buck and boost conversion between buses. A single controller can deliver up to 3.75 kW with conversion efficiency of greater than 95%, and can interleave in a modular master/slave architecture (up to four chips) to achieve higher powers. 48V is appearing in more designs, Intersil says; it is more effective at delivering power to the road, and offers better regenerative braking. Alternators – in fact a starter/generator – in mixed architectures will be at 48V, so generating the 12V rail is a buck operation. Many functions that are now mechanically or hydraulically driven will be electrified; for example, oil pumps and electric turbochargers.
One ISL78226 eliminates the complexity of earlier designs, Intersil says. It responds to changing load requirements by dropping phases and can handle abrupt load changes. It has a PMBus interface, and internal limp-home mode. The chip can remove much of the complexity associated with design of a 48V ‘mild hybrid’, Intersil says.
Features include; average phase-to-phase current balancing; cycle-by-cycle peak current limiting, negative current limiting and programmable current limits; analog and digital voltage control; supply and clock redundancy for functional safety; and a 200 mA linear-regulator auxiliary output. The device is AEC-Q100 Grade-1 qualified for -40 to +125C operation.
In a 10 x 10 mm 64-lead TQFP the IC costs $6.95 (1000); an evaluation board is available.
Intersil; www.intersil.com/products/isl78226
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