BQ24901 Datasheet, PDF (13/18 Pages) Texas Instruments – SINGLE-CELL LI-ION AND LI-POL CHARGE MANAGEMENT IC FOR OFFLINE APPLICATIONS

bq24901
STATE MACHINE
STATUS
1
Following power-on
reset (POR)
2 Following POR
3 Pre-conditioning
Fastcharge
4 (current or voltage
regulation)
5 Charge suspend
6 Charge suspend
7 Charge suspend
8 Charge suspend
9 Charge suspend
10 Timer fault
11 Timer fault
12 Timer fault
13 Timer fault
14 Timer fault
15 Done
SLUS527 – DECEMBER 2002
APPLICATION INFORMATION
Table 1. State Machine Status
BATTERY PACK
STATUS
New pack insertion.
New deeply-discharged
battery (with an open
protector inserted).
Pack is removed.
Pack is removed.
Pack is removed.
Pack is removed. A new
pack with normal tempera-
ture inserted.
Pack is removed. A new
pack with abnormal
temperature inserted.
Pack is removed. A pack
with open protector and nor-
mal temperature inserted
Pack is removed. A pack with
open protector and abnormal
temperature inserted
Pack remains in charger.
Pack is removed.
ACTION
h _{The device remains in the battery presence detection loop until a new battery is}
detected.
h _{Depending on the battery voltage, the device either enters pre–charge or fast}
charge.
h _{The device remains in the battery presence detection loop until a new battery is}
detected.
h _{Depending on the battery voltage, the device either enters pre–charge or fast}
charge.
h _{The device enters fast charge (since the output capacitor rises above VLOWV) and}
terminates immediately due to ITERM detection.
h _{The device then enables IDISCHG for tDISCHG2. In the absence of a battery, the}
BAT voltage falls below VRCH, prompting the device to indicate BATTERY
ABSENT. If the battery is present the BAT voltage does not fall below VRCH and
therefore device assumes a battery is still connected and indicates DONE on
STAT pins.
h _{The device terminates immediately due to ITERM detection.}
h _{The device then enables IDISCHG for tDISCHG2. In the absence of a battery, the}
BAT voltage falls below VRCH, prompting the device to indicate BATTERY
ABSENT. If the battery is present the BAT voltage does not fall below VRCH and
therefore device assumes a battery is still connected and indicates DONE on
STAT pins.
h _{The device remains the charge suspend mode as long as the TS pin voltage is}
outside the VLTF to VHTF range.
h _{The device leaves the charge-suspend mode and resumes charging depending}
on the battery voltage.
h _{The device resets the timers only if it enters a charge mode different from where}
the initial charge suspend condition happened (for instance from pre-charge to
fast or vice versa)
h _{The device remains the charge suspend mode as long as the TS pin voltage is}
outside the VLTF to VHTF range.
h _{Once temperature returns to normal, item 6 in this table applies.}
h _{The device leaves the charge suspend mode.}
h _{The device enters pre-charge (since the voltage is below VLOWV). This action}
closes the protector and charging resumes.
h _{The device remains the charge suspend mode as long as the TS pin voltage is}
outside the VLTF to VHTF range.
h _{Once temperature returns to normal, item 8 in this table applies.}
h _{The device remains in the fault condition until POR or battery removal is detected.}
h _{Once in the fault mode, the device applies the IDETECT current to the output. The}
purpose of this current is to detect the removal of the pack.
h _{If voltage regulation can be maintained with IDETECT current, the device assumes}
the pack has been removed (and only output capacitor is present).
h _{The device then awaits battery insertion as outlined item 1 of this table.}
Pack is removed. A new
pack is inserted.
h _{See item 11 in this table.}
Pack is removed. A new
pack with open protector is
inserted.
Pack remains in charger.
Pack is removed.
h _{See items 11 and 12 in this table.}
h _{The bq24901 in the Done state as long as the pack voltage is above the VRCH}
threshold. While in the done state there is no current flow to the battery (zero
current)
h _{While in the DONE state, the device monitors the BAT voltage and initiates a new}
cycle once the BAT voltage falls below VRCH threshold (this happens as the output
capacitor discharges through the input leakage on the BAT pin).
h _{While in the DONE state, the device monitors the BAT voltage and initiates a new}
cycle once the BAT voltage falls below VRCH threshold (this happen as the output
capacitor discharges through the input leakage on the BAT pin).
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