BQ24153A Datasheet, PDF (19/43 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger

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bq24153A
bq24156A, bq24158
SLUSAB0 – OCTOBER 2010
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 27. Timer Flow Chart for bq24153A/6A/8
USB Friendly Boot-Up Sequence
Prior to power up if the host continues to write the TMR_RST bit to 1, to stay in 32 second mode, on power up
the charger enters normal charge mode (using the desired control bits). If not in 32 second mode at power up,
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
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 sets the input current limit to 100mA for a logic low and 500mA for a logic high,
whereas the bq24156A defaults to 500mA. In 32 second mode, the input current limit is set by the programmed
control bits in register 01H.
Thermal Regulation and Protection
To prevent overheating of the chip during the charging process, the IC monitors the junction temperature, T_J, of
the die and begins to taper down the charge current once T_J reaches the thermal regulation threshold, T_CF. The
charge current is reduced to zero when the junction temperature increases approximately 10°C above T_CF. In
any state, if T_J exceeds T_SHTDWN, the IC suspends charging. In thermal shutdown mode, PWM is turned off and
all timers are frozen. Charging resumes when T_J falls below T_SHTDWN by approximately 10°C.
Input Voltage Protection in Charge Mode
Sleep Mode
The IC enters the low-power sleep mode if the VBUS pin voltage falls below the sleep-mode entry threshold,
V_CSOUT+V_SLP, and VBUS is higher than the bad adaptor detection threshold, V_IN(MIN). This feature prevents
draining the battery during the absence of V_BUS. During sleep mode, both the reverse blocking switch Q1 and
PWM are turned off.
Copyright © 2010, Texas Instruments Incorporated
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Product Folder Link(s): bq24153A bq24156A bq24158