BQ25070 Datasheet, PDF (13/21 Pages) Texas Instruments – 1A, Single-Input, Single-Cell LiFePO4 Linear Battery Charger with 50mA LDO

bq25070
www.ti.com
Table 1. Pulse Counting Map for CTRL Interface
# of Pulses
1
2
3
4
5
6
7
8
9
10
11
>11
Current Limit
No Change
No Change
No Change
93 mA
187 mA
280 mA
374 mA
467 mA
654 mA
794 mA
935 mA
No Change
SLUSA66 – JULY 2011
If, at any time, the CTRL input is held high for more than 2ms, the IC is disabled. When disabled, charging is
suspended and the bq25070 input quiescent current is reduced.
IC can be
programmed during
tWAIT
# of pulses decoded once
CTRL pulled low for 2.0ms
IC disabled if CTRL
pulled high for >2.0ms
t_HI
CTRL
tCTRL_DGL
2.0ms
tCTRL_LATCH
2.0ms
tCTRL_LATCH
2.0ms
tCTRL_LATCH
t_LO
Power up with default
285mA current limit
475mA current limit
programmed
190mA current limit
programmed
I_IN
Figure 15. CTRL Timing Diagram
THERMAL REGULATION AND THERMAL SHUTDOWN
The bq25070 contains a thermal regulation loop that monitors the die temperature continuously. If the
temperature exceeds T_J(REG), the device automatically reduces the charging current to prevent the die
temperature from increasing further. In some cases, the die temperature continues to rise despite the operation
of the thermal loop, particularly under high V_IN conditions. If the die temperature increases to T_J(OFF), the IC is
turned off. Once the device die temperature cools by T_J(OFF-HYS), the device turns on and returns to thermal
regulation. Continuous over-temperature conditions result in the pulsing of the load current. If the junction
temperature of the device exceeds T_J(OFF), the charge FET is turned off. The FET is turned back on when the
junction temperature falls below T_J(OFF) – T_J(OFF-HYS).
Note that these features monitor the die temperature of the bq25070. This is not synonymous with ambient
temperature. Self heating exists due to the power dissipated in the IC because of the linear nature of the battery
charging algorithm.
Copyright © 2011, Texas Instruments Incorporated
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