BQ24085 Datasheet, PDF (15/34 Pages) Texas Instruments – 750 mA SINGLE-CHIP Li-Ion/Li-Pol CHARGE MANAGEMENT IC WITH THERMAL REGULATION

bq24085, bq24086
bq24087, bq24088
www.ti.com .................................................................................................................................................... SLUS784B – DECEMBER 2007 – REVISED MAY 2008
CONTROL LOGIC OVERVIEW
An external host can enable or disable the charging process using a dedicated control pin, CE. A low-level signal
on this pin enables the charge, and a high-level signal disables the charge. The bq24085/6/7/8 is in stand-by
mode with CE = HI. When the charger function is enabled (CE = LO) a new charge is initiated.
Table 1 describes the charger control logic operation, in bq24085/6/7/8 versions without the TS pin the pack
temp status is internally set to OK.
Table 1. Control Logic Functionality
bq24085/6/7/8
OPERATION
MODE
CE
INPUT
POWER
TIMER
FAULT
(latched)
OUTPUT
SHORT
CIRCUIT
TERMINATION
(latched)
POWER
DOWN
LO
Low
X
X
X
SLEEP
X
Not
Detected
X
X
X
STANDBY
HI Detected
X
X
X
LO Detected
X
Yes
X
LO Detected
No
No
Yes
LO Detected
Yes
No
No
SEE STATE ^{LO Detected}
No
No
Yes
DIAGRAM
LO Detected
No
No
No
LO Detected
No
No
No
LO
Over
Voltage
No
No
No
CHARGING LO Detected
No
No
No
PACK
TEMP
X
X
X
X
X
X
Absent
Hot or
Cold
Ok
Ok
Ok
THERMAL
SHUTDOWN
X
POWER
DOWN
Yes
CHARGER
POWER
STAGE
OFF
X
No
OFF
X
No
OFF
X
No
X
No
OFF
X
No
IFAULT
T_J < T_SHUT
No
IDETECT
T_J < T_SHUT
No
OFF
T_J < T_SHUT
No
OFF
T_J < T_SHUT
No
OFF
T_J < T_SHUT
No
ON
In both STANDBY and SUSPEND modes the charge process is disabled. In the STANDBY mode all timers are
reset; in SUSPEND mode the timers are held at the count stored when the suspend mode was set.
The timer fault, termination and output short circuit variables shown in the control logic table are latched in the
detection circuits, outside the control logic. Refer to the timers, termination and short circuit protection sections
for additional details on how those latched variables are reset.
TEMPERATURE QUALIFICATION (Applies only to versions with TS pin option)
The bq24085/6/7/8 devices continuously monitor the battery temperature by measuring the voltage between the
TS and VSS pins. The IC compares the voltage on the TS pin against the internal V_(TS1) and V_(TS2) thresholds to
determine if charging is allowed. Once a temperature outside the V_(TS1) and V_(TS2) thresholds is detected the IC
immediately suspends the charge. The IC suspends charge by turning off the power FET and holding the timer
value (i.e., timers are NOT reset). Charge is resumed when the temperature returns to the normal range.
Copyright © 2007–2008, Texas Instruments Incorporated
Submit Documentation Feedback
15
Product Folder Link(s): bq24085, bq24086 bq24087, bq24088