ISL9241 USB-C™ Combo Buck-Boost Battery Charger

Added on 2018-12-04

Renesas Electronics Corporation introduces the ISL9421 USB-C™ buck-boost battery charger to support both Narrow Voltage Direct Charging (NVDC) and Hybrid Power Buck-Boost (HPBB) charging for notebooks, ultrabooks, tablets, 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 efficiently processing a full range of power levels.


Welcome to this short product introduction video for the ISL9241 buck-boost battery charger, the latest addition to Renesas’s family of multi-cell battery charger products.

In recent years, many electronic devices using multi-cell battery packs have adopted USB-C ports, such as laptop computers, portable speakers, cameras, and power banks. [1][2]

As a true all-in-one port, USB-C is capable of delivering bidirectional data and providing power to charge the battery in these devices. Because of its wide voltage range of 5V to 20V, USB-C battery charging requires a fundamental change to the existing power delivery architecture.

Renesas is capitalizing on the exciting new trend of USB-C PD and has a complete product portfolio including PD controllers and battery chargers.

The existing products in the line-up are Narrow Voltage DC (NVDC) buck-boost battery chargers. The input power goes through the battery charger and is delivered to the system [1], while the battery may be charged or not charged.

In extreme cases where system power demand is higher than the input power, the battery could be discharged to support the system power and prevent Vsys voltage collapse [2][3].

NVDC topology is a good option for lower power systems because it can reduce system complexity. For example, it is suitable for lower power systems such as those with less than 60W of power with 2-cell battery packs [4]

However, NVDC buck-boost chargers have some limitations. NVDC topology has to use bigger size components (such as inductors and H-bridge FETs) for higher power systems because its components have to be sized to handle the total system power and battery charging power, which in turn may lead to a higher BOM cost [5].

ISL9241 is a new kind of buck-boost charger combining both NVDC (Narrow Voltage DC) and HPBB (Hybrid Power Buck-Boost) modes into a single-chip solution. This combo solution provides great flexibility to customer designs with improved efficiency and optimized system performance [1].

In traditional NVDC mode, ASGATE is off and BSGATE is on [2] and the ISL9241 is operating in normal NVDC mode.

In the HPBB mode, ASGATE is on with BSGATE off [3]. Now ISL9241 delivers input power to a system without going through the charger switchers, which enables highest possible efficiency. The charger may or may not be switched to charge the battery depending on the battery state of charge.

HPBB is also called bypass mode. With the control of ASGATE and BSGATE on/off, ISL9241 can work in either NVDC or HPBB mode and this mode transition is achieved by sending SMBus commands from the EC in the system [4].

HPBB configuration is usually used for 3- to 4-cell battery systems with higher power adapters which have sufficient capability to provide system power [1]. In HPBB configuration, ISL9241 can also work in the reverse turbo-boost mode by pumping energy from the battery to the Vadp side to support the system peak power load.

The ISL9241 battery charger gives customers the highest level of flexibility along with optimized system performance and maximum efficiency.

ISL9241 provides the charging function, system bus regulation and protection features using only NFETs for efficiency optimization.

ISL9241 can operate with only a battery, only an adapter, or both connected. For Intel IMVP compliant systems, ISL9241 includes System Power monitor (PSYS) functionality, which provides an analog signal representing total platform power. ISL9241 also has processor hot (PROCHOT#) monitor and supports supplemental mode which meets Intel’s Vmin Adaptive Protection (VAP) requirement by keeping the battery voltage above a defined minimum voltage level. ISL9241 serial communication uses SMBus/I2C, which allows programming of many key parameters to deliver a customized solution.

The integrated 8-bit ADC in the ISL9241 enables key system parameter telemetry, such as temperature (PCB and junction), adapter current/voltage, and battery charge/discharge current and system bus voltage.

ISL9241 can also be enabled for autonomous charging and end of charge without communication from an embedded controller.

ISL9241 shares the same 32-pin TQFN package as the ISL9237/8 with 6 pin differences, which allows customers to do a co-layout for new project designs. In addition, the register map for both the ISL9241 and ISL9237/8 are highly compatible, which minimizes the EC firmware changes and reduces the development effort when adopting ISL9241 in new designs and across multiple platforms.

The new ISL9241 buck-boost battery charger controller is supported by an easy to use graphical GUI, giving customers everything they need to start a battery charger design for their next-generation products.

Please visit the ISL9241 product page for the latest information on this device and access to all online tools and resources. Thanks for watching!