BQ25071-Q1 Datasheet, PDF (12/22 Pages) Texas Instruments – Automotive Qualified

bq25071-Q1
SLUSCD6 – APRIL 2016
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Feature Description (continued)
8.3.4 50-mA LDO (LDO)
The LDO output of the bq25071-Q1 is a low dropout linear regulator (LDO) that supplies up to 50 mA while
regulating to V_(LDO). The LDO is active whenever the input voltage is above V_(UVLO) and below V_(OVP). It is not
affected by the EN input. The LDO output is used to power and protect circuitry such as USB transceivers from
transients on the input supply.
8.3.5 Charge Status Indicator (CHG)
The bq25071-Q1 contains an open drain CHG output that indicates charging state and faults. When charging a
battery in precharge or fastcharge mode, the CHG output is pulled to GND. Once the BAT output reaches the
overcharge voltage threshold, CHG goes high impedance to signal the battery is fully charged. When the battery
voltage drops below the recharge voltage threshold the CHG output is pulled low to signal the host of a new
charge cycle. Connect CHG to the required logic level voltage through a 1 kΩ to 100 kΩ resistor to use the signal
with a microprocessor. I_(CHG) must be below 5 mA.
The IC monitors the CHG pin when no input is connected to verify if the system circuitry is active. If the voltage
at CHG is logic being drive low when no input is connected, the TS circuit is turned off for a low quiescent current
state. Once the voltage at CHG increases above logic high, the TS circuit is turned on.
8.3.6 Input Current Limit Control (EN)
The bq25071-Q1 contains a 3-state that controls the input current limit. Drive EN low to program the input current
limit to the user defined value programmed using ISET. Drive EN high to place the bq25071-Q1 in USB suspend
mode. In USB suspend mode, the input current into bq25071-Q1 is reduced. Leaving EN unconnected or
connected to a high impedance source programs the USB500 input current limit.
Table 1. EN Input Definition
EN
MODE
Low
ISET
Hi-Z
USB500
Hi
USB Suspend
12
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