November 9, 2016 – Intersil announced a 6-phase bidirectional PWM controller designed to perform buck and boost power conversions between 12V and 48V automotive buses. The automotive-grade ISL78226 delivers 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 allows engineers to support the rapid adoption of 48V hybrid powertrains that provide improved emissions and better fuel economy for internal combustion engine/electric mild hybrids.
Previously, 48V systems required a DSP with complicated firmware and/or separate buck and boost controllers combined with power stages and complex switching logic. One ISL78226 controller is designed to eliminate the complexity associated with previous 48V designs. The controller responds to changing load requirements by automatically adding or dropping phases to maximize system efficiency. It can also manage an abrupt change in power conversion direction. For example, if the 48V starter/generator fails while the vehicle is driving, the ISL78226 DC/DC controller reverses power conversion direction so the 12V battery will temporarily supply the 48V subsystems, such as power steering, allowing the vehicle to safely pull over and stop.
The ISL78226 controller also 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, allowing the vehicle to be driven home or to a nearby service station for repairs.
Key Features and Specifications of ISL78226
- 6-phase bidirectional synchronous 12-48V controller regulates voltage and current
- 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
- Analog/digital control of output voltage
- Selectable phase-dropping and diode emulation for light load efficiency improvement
- Phase dropping enabled with companion ISL78420 FET driver family featuring tri-level input
- 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 operation from -40°C to +125°C
