The ISL95521 is a highly versatile combo battery charger

configurable for operating as either a Hybrid Power Boost (HPB)

charger or a Narrow VDC (NVDC) charger, supporting 2-, 3- or 4-cell

batteries. Both configurations allow the battery to work with the

adapter together to supply the system load when it exceeds the

adapter capability, referred to as system Turbo mode. The HPB

charger configuration reverse-boosts battery energy to system bus in

order to help the adapter provide the system power in Turbo mode.

NVDC charger configuration quickly turns on BGATE to enable the

battery to help the adapter provide the system power in Turbo mode.

The ISL95521 uses N-channel MOSFETs (NFETs) for all the switches

to achieve the best performance and lowest BOM cost. The internal

charge pump is capable of turning on all the NFETs fast or slow

depending on the circumstance or the need. The ability to quickly

turn on NFETs prevents system bus voltage drop when the battery is

suddenly removed in Turbo mode or in battery learn mode.

The ISL95521 provides many protection features including a

PROCHOT# indicator for system low voltage, adapter overcurrent,

battery overcurrent or overheating, with an array of SMBus

programmable parameters for maximum flexibility. It also features

hardware based adapter current limit and battery-current limit in

addition to SMBus programmable limits.

The ISL95521 provides a high accuracy adapter current monitor,

battery current monitor and system power monitor outputs. To

provide maximum flexibility for working with high power and low

power systems, it provides several configurable current-sense

resistor value options to achieve the best trade-off of current sensing

accuracy vs power loss.

The ISL95521 uses the Intersil patented Robust Ripple Regulator

(R3™) modulation scheme to provide excellent light load efficiency

and fast dynamic response. It is available in a 32 Ld 4x4mm2 QFN

package.

Features

• Configurable as HPB charger or NVDC charger

• Compliant with Intel PROCHOT# and PSYS requirements

• Adapter current monitor and battery discharging current

monitor

• Uses NFET for all the switches

- Supports removal of battery during battery learn mode

- Actively controlled inrush current to prevent FET damage

• SMBus programmable settings and high accuracy

• Comprehensive protection features include

- PROCHOT# indicator for system low voltage, adapter

overcurrent, battery overcurrent or system overheating

- Hardware-based adapter current and battery current limits

- Supports sudden removal of battery in system Turbo mode

• 16 switching frequency options from 350kHz to 1MHz

• Low quiescent current

• SMBus and auto-increment I2C compatible

• Intersil Robust Ripple Regulator (R3™) modulation scheme

provides excellent light load efficiency and fast dynamic response

• 32 Ld 4x4mm2 QFN package

• Pb-free (RoHS compliant)

Applications

• Devices with rechargeable 2-, 3- or 4-cell batteries