6-phase DC/DC controller for 12V to 48V automotive systems

According to Intersil, the 6-phase bidirectional Pulse Width Modulation (PWM) controller is the first designed to perform buck and boost power conversions between 12V and 48V automotive buses. A single automotive-grade ISL78226 is said to deliver up to 3.75kW at greater than 95% conversion efficiency, and is able to interleave in a modular master/slave architecture to deliver higher power.

This design is claimed to allow engineers to support the adoption of 48V hybrid powertrains that provide improved emissions and better fuel economy for internal combustion engine/electric mild hybrids.

According to the company, one ISL78226 controller eliminates the complexity associated with previous 48V designs. The controller responds to changing load requirements by automatically adding or dropping phases to maximise system efficiency. It can also manage an abrupt change in power conversion direction.

The controller integrates a digital PMBus interface for system control, telemetry and diagnostics that support ISO 26262 functional safety requirements. The controller’s limp-home mode reduces power in the event of a serious fault or failure.

Key features:

  • Master/slave architecture supports up to four ICs in parallel
  • Average phase-to-phase current balancing and average current output with ±1.5% accuracy
  • Cycle-by-cycle peak current limiting, negative current limiting, and digitally programmable average current limit
  • Analogue/digital control of output voltage
  • Programmable automatic driver bootstrap capacitor refresh pulses
  • Supply and clock redundancy for functional safety
  • Dual-output flyback controller and 200mA adjustable output linear regulator
  • AEC-Q100 Grade-1 qualified for temperatures ranging from -40 to 125°C
  • Author
    Peggy Lee