bq25071

TS

TEMP

PACK+

PACK -

+

+

V

HOT

V

COLD

R2

R1

LDO

bq25071

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SLUSBK6 – JULY 2014

Feature Description (continued)

For applications that do not require the TS monitoring function, set R1 = 490 k

Ω and R2 = 100 kΩ to set the TS

voltage at a valid level and maintain charging.

Figure 7. NTC Monitoring Function

9.3.4 50 mA LDO (LDO)

The LDO output of the bq25071 is a low dropout linear regulator (LDO) that supplies up to 50 mA while

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.

9.3.5 Charge Status Indicator (CHG)

The bq25071 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 k

Ω to 100 kΩ resistor to use the signal

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.

9.3.6 Input Current Limit Control (EN)

The bq25071 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 in USB suspend

mode. In USB suspend mode, the input current into bq25071 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

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