Renesas has introduced a pair of automotive dc-dc converter chips with low operating current for ‘always-on’ applications. Both are designed to work with external mosfet power stages.

Renesas-ISL78263-block

ISL78264 is a 50W-200W synchronous dual buck controller intended to manage the intermediate first stage dc-dc conversion, stepping down the 12V battery system to 5V and 3.3V to power ECUs (electronic control units), in-vehicle infotainment and digital cockpits.

• 3.75 to 42Vin
• Buck1 output fixed at 3.3V/5V or adjustable from 0.8V to 5V
• Buck2 output adjustable from 0.8V to 32V
• Few microamp operation possible
• 25ns on-times for low duty-cycle operation
• 180° phase shift between channels
• Supports start-stop cranking transients down to 5.5V at 2MHz

ISL78263  (both diagrams) is a 25W-100W synchronous boost-plus-buck controller which can provide a pre-boost if battery voltage dips to as low as 2.1V during a cranking transient or a start/stop event.

• 2.1 to 42Vin
• Buck output 3.3V, 5V, adjustable
• Buck drop-out mode for high duty-cycle operation
• Boost frequency at 1x or 0.2x the buck frequency
• 25ns on-times for low duty-cycle operation

To control the external mosfets, the internal gate drivers can source 2A and sink 3A.

“The ISL78264 and ISL78263 provide the ideal primary stage power regulation solutions for Renesas’ R-Car H3 and R-Car M3 SoCs,” according to Renesas v-p Niall Lyne. “The controllers’ always-on low quiescent current gives power system designers the margin they need to stay within their 100µA power budget, and can even manage budgets down to 50µA.”

For each individual buck channels, the company claims 6µA (typ) operation. According to the ISL78264 data sheet, this comes with the following caveats: ‘Energy conservation mode’, no external load on Vout, measurements are taken when the output is not switching.

In energy conservation mode, the buck supplies 5V to very light loads by delivering power pulses to the output filter and load at a frequency much lower than the normal switching frequency.

Shutdown current is 300nA typically and 6µA max, while no-load supply current once switching at 2.2MHz is 11mA typ and 25mA max.

In normal operation, up to 96% effieicny is possible, as is >10A output current.

Both parts are protected against over-voltage, under-voltage, over-current, over-temperature and bootstrap under-voltage.

Operation is AEC-Q100 Grade-1 qualified over -40°C to +125°C ambient.

Packaging is 5 x 5mm, 32lead wettable flank QFN.