Low IQ Linear Battery Charge Management Solution with LDO and ADCSeptember 07, 2019 by Paul Shepard
The BQ25150 from Texas Instruments is a highly integrated battery charge management IC that integrates the most common functions for wearable devices, namely a charger, an output voltage rail, ADC for battery and system monitoring, and push-button controller.
The BQ25150 IC integrates a linear charger that enables quick and accurate charging for small batteries. The device supports charge current up to 500mA and supports termination current down to 0.5mA 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 I2C 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 12-bit effective 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 a 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 I2C interface making the BQ25150 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 I2C allowing the host to customize the thermal charging profile.
The charger is optimized for 5V USB input, with 20V 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 I2C.
Summary of Features
- Linear battery charger with 1.25-mA to 500-mA fast charge current range
- 5% Accurate I2C programmable battery regulation voltage ranging from 3.6 V to 4.6 V in 10-mV steps
- Configurable termination current supporting down to 0.5 mA
- 20-V Tolerant input with typical 3.4-V to 5.5-V input voltage operating range
- Programmable thermal charging profile, fully configurable hot, warm, cool and cold thresholds
- Power path management for powering system and charging battery
- Dynamic power path management optimizes charging from weak adapters
- Advanced I2C control allows host to disconnect the battery or adapter as needed
- I2C Configurable load switch or up to 150-mA LDO output
- Programmable range from 0.6 V to 3.7 V in 100-mV steps
- Ultra low Iddq for extended battery life
- 10-nA Ship mode battery Iq
- 400-nA Iq While powering the system (PMID and VDD on)
- One push-button wake-up and reset input with adjustable timers
- Supports system power cycle and HW reset
- 12-Bit effective ADC
- Monitoring of charge current, battery thermistor and battery, input and system (PMID) voltages
- General purpose ADC input
- Always on 1.8-V VDD LDO supporting loads up to 10 mA
- 20-Pin 2-mm x 1.6-mm CSP package
- 12-mm2 Total solution size