500-mA 1-cell linear charger with 10-nA IQ, power path, regulated system voltage, 16-bit ADC and LDO | YFP | 20 | -40 to 85

The BQ25157

is a highly integrated battery charge management IC that integrates the most common

functions for wearable, portable and small medical devices, namely a charger, a regulated

output voltage rail for system power, ADC for battery and

system monitoring, a LDO, and push-button controller. The BQ25157 has the Input

Supply Over Voltage Threshold (V OVP) threshold set to 6.2 V.

The BQ25157

IC integrates a linear charger with Power Path that enables quick and accurate

charging for small batteries while providing a regulated voltage to the system. The

regulated system voltage (PMID) output may be configured through I 2C

based on the recommended operating condition of downstream IC’s and system loads for

optimal system operation.

The device supports charge current up

to 500 mA and supports termination current down to 0.5 mA for maximum charge. The

battery is charged using a standard Li-Ion charge profile with three phases:

pre-charge, constant current and constant voltage regulation.

The device integrates advanced power path

management and control that allows the device to provide power to the system while

charging the battery even with poor adapters. The host may also control the power

path through I 2C allowing it to disconnect the input adapter and/or

battery without physically removing them. The single push-button input eliminates

the need of a separate button controller IC reducing the total solution footprint.

The push-button input can be used for wake functions or to reset the system. A 16-bit ADC enables accurate battery voltage

monitoring and can be used to enable a low Iq gauging to monitor battery health.

It can also be used to measure the battery temperature using a thermistor

connected to the TS pin as well as external system signals through the ADCIN

pin. The low quiescent current during operation and shutdown enables

maximum battery life. The input current limit, charge current, LDO output voltage,

and other parameters are programmable through the I 2C interface making

the BQ25157 a very flexible charging

solution. A voltage-based JEITA compatible (or standard HOT/COLD) battery pack

thermistor monitoring input (TS) is included that monitors battery temperature and

automatically changes charge parameters to prevent the battery from charging outside

of its safe temperature range. The temperature thresholds are also programable

through I 2C allowing the host to customize the thermal charging profile.

The charger is optimized for 5-V USB input, with 20-V absolute maximum tolerance to

withstand line transients. The device also integrates a linear regulator to provide

a quiet rail for radios or processors and can be independently sourced and

controlled through I 2C.