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USB-C combo buck-boost battery charger for mobile computing systems

Renesas has introduced the industry’s first USB-C buck-boost battery charger to support both Narrow Voltage Direct Charging (NVDC) and Hybrid Power Buck-Boost (HPBB) charging for mobile devices and power banks using the reversible USB Type-C connector cable.

Through firmware control, the ISL9241 can switch between NVDC and HPBB modes, providing a low-cost and small solution size capable of processing a full range of power levels.

It leverages Renesas’ advanced R3 modulation technology for superior light-load efficiency and ultra-fast transient response to extend battery run-time. The charger’s reconfigurable internal registers allow the use of a smaller inductor for HPBB mode to achieve higher efficiencies across multiple power levels.

The ISL9241 delivers charging, system bus regulation, and protection features using NFETs for highest efficiency and bill of material (BOM) cost optimisation and can operate with only a battery, only an adapter, or both connected.

It takes DC input power from conventional adapters, travel adapters, and USB Type-C power delivery (PD) ports, and safely charges battery packs with up to four-cell Li-ion series batteries.

In NVDC mode, the ISL9241 automatically selects the adapter or battery as the source for system power. NVDC operation also supports turbo mode by turning on the BGATE FET to limit adapter current at the adapter’s current limit set point. NVDC is the ISL9241’s initial start-up state before the system controller’s firmware changes the configuration to HPBB. In higher power HPBB mode, the ISL9241 supports bypass, bypass plus charging, reverse turbo-boost mode, and reverse turbo-boost mode plus charging.

The ISL9241 provides 5V to 20V reverse buck, boost, or buck-boost operation to the adapter port (OTG mode) allowing configurations to support USB-C PD output for fast charging Programmable Power Supply (PPS) ports.

Direct charging the battery can also be enabled by bypassing the ISL9241 in PPS mode.

The ISL9241’s reconfigurable charging architecture also allows designers to use the charger for multiport configurations while remaining fully compliant with the USB PD3.0 standard.

Several digital telemetry, fault monitoring and protection features are provided. In addition, the ISL9241 also features a supplemental power mode that allows the input bias capacitor to store energy and release it during high power demand.

Author
Neil Tyler

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