BQ24158_12 Datasheet, PDF (19/45 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger

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bq24153A, bq24156A
bq24158, bq24159
SLUSAB0A – OCTOBER 2010 – REVISED FEBRUARY 2012
Charge Start
Start T15 min
Timer
Reset Charge
Parameters
T 15 min Active ?
Yes
Yes
No
Start T32 sec
Stop T15 min
Yes
Any I ² C Write -
Action ?
No
T 15 min
Expired ?
T 32 sec Expired ?
No
Charge
No
Host Should Reset
T 32 sec Timer
Yes
Timer Fault
Figure 29. Timer Flow Chart for bq24153A/6A/8/9
USB FRIENDLY POWER UP
Prior to POR, if the host continues to write the TMR_RST bit to 1, to stay in 32-second mode, then at POR, the
charger enters normal charge mode (using the desired control bits). If not in 32-second mode at POR, the charge
will operate with default bit values, in 15 minute mode, until the host updates the control registers.
If the battery voltage is above the V_LOWV threshold while in 15 minute mode, the charger will be in the high
impedance state. The default control bits set the charging current and regulation voltage low as a safety feature
to avoid violating USB spec and over-charging any of the Li-Ion chemistries, while the host has lost
communication. The input current limiting is described below.
INPUT CURRENT LIMITING AT POWER UP
The input current sensing circuit and control loop are integrated into the IC. When operating in 15-minute mode,
for bq24153A/8, the OTG pin logic level sets the input current limit to 100mA for a logic low and 500mA for a
logic high, whereas the bq24156A/9 defaults to 500mA. In 32 second mode, the input current limit is set by the
programmed control bits in register 01H.
CHARGE MODE OPERATION
Charge Profile
Once a good battery with voltage below the recharge threshold has been inserted and a good adapter is
attached, the bq2415x enters charge mode. In charge mode, the IC has five control loops to regulate input
voltage, input current, charge current, charge voltage and device junction temperature. During the charging
process, all five loops are enabled and the one that is dominant takes control. The IC supports a precision Li-ion
or Li-polymer charging system for single-cell applications. Figure 30 (a) indicates a typical charge profile without
input current regulation loop. It is the traditional CC/CV charge curve, while Figure 30(b) shows a typical charge
profile when input current limiting loop is dominant during the constant current mode. In this case, the charge
current is higher than the input current so the charge process is faster than the linear chargers. For
bq24153A/6A/8/9, the input voltage threshold for DPM loop, input current limits, the charge current, termination
current, and charge voltage are all programmable using I²C interface.
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Product Folder Link(s): bq24153A bq24156A bq24158 bq24159