BQ24195 Datasheet, PDF (29/41 Pages) Texas Instruments – I2C Controlled 2.5A / 4.5A Single Cell USB/Adapter Charger With 5.1V at 1A / 5.1V at 2.1A Synchronous Boost Operation

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bq24195
bq24195L
SLUSB97 – OCTOBER 2012
During thermal regulation, the actual charging current is usually below the programmed battery charging current.
Therefore, termination is disabled, the safety timer runs at half the clock rate, and the status register REG08[1]
goes high.
Additionally, the device has thermal shutdown to turn off the converter. The fault register REG09[5:4] is 10 and
an INT is asserted to the host.
Voltage and Current Monitoring in Buck Mode
The bq24195L, bq24195 closely monitors the input and system voltage, as well as HSFET and LSFET current for
safe buck mode operation.
Input Over-Voltage (ACOV)
The maximum input voltage for buck mode operation is 18V. If VBUS voltage exceeds 18V, the device stops
switching immediately. During input over voltage (ACOV), the fault register REG09[5:4] will be set to 01. An INT
is asserted to the host.
System Over-Voltage Protection (SYSOVP)
The charger device monitors the voltage at SYS. When system over-voltage is detected, the converter is stopped
to protect components connected to SYS from high voltage damage.
Current Monitoring in Boost Mode
The bq24195L, bq24195 closely monitors LSFET current to ensure safe boost mode operation.
Battery Protection
Battery Over-Current Protection (BATOVP)
The battery over-voltage limit is clamped at 4% above the battery regulation voltage. When battery over voltage
occurs, the charger device immediately disables charge. The fault register REG09[5] goes high and an INT is
asserted to the host.
Charging During Battery Short Protection
If the battery voltage falls below 2V, the charge current is reduced to 100mA for battery safety.
System Over-Current Protection
If the system is shorted or exceeds the over-current limit, the BATFET is latched off. DC source insertion on
VBUS is required to reset the latch-off condition and turn on BATFET.
Serial Interface
The bq24195L, bq24195 uses I²C compatible interface for flexible charging parameter programming and
instantaneous device status reporting. I2C^TM is a bi-directional 2-wire serial interface developed by Philips
Semiconductor (now NXP Semiconductors). Only two bus lines are required: a serial data line (SDA) and a serial
clock line (SCL). Devices can be considered as masters or slaves when performing data transfers. A master is
the device which initiates a data transfer on the bus and generates the clock signals to permit that transfer. At
that time, any device addressed is considered a slave.
The device operates as a slave device with address 6BH, receiving control inputs from the master device like
micro controller or a digital signal processor. The I²C interface supports both standard mode (up to 100kbits), and
fast mode (up to 400kbits).
Both SDA and SCL are bi-directional lines, connecting to the positive supply voltage via a current source or pull-
up resistor. When the bus is free, both lines are HIGH. The SDA and SCL pins are open drain.
Data Validity
The data on the SDA line must be stable during the HIGH period of the clock. The HIGH or LOW state of the
data line can only change when the clock signal on the SCL line is LOW. One clock pulse is generated for each
data bit transferred.
Copyright © 2012, Texas Instruments Incorporated
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