Datasheet

www.ti.com
Autonomous Power Source Selection
USB MODE
AC MODE
AC > BATTERY
AC < BATTERY
USB > BATTERY
Battery Pre-Conditioning
I
O (PRECHG)
+
V
(PRECHG)
K
(SET)
R
SET
(1)
Battery Charge Current
I
O (OUT)
+
V
(SET)
K
(SET)
R
SET
(2)
Battery Voltage Regulation
Charge Taper Detection, Termination and Recharge
bq25010
bq25011
bq25012
SLUS615B – DECEMBER 2004 – REVISED JULY 2007
As default, the bq2501x attempts to charge the battery from the AC input. If AC input is not present, the USB
input is selected. If both inputs are available, the AC adapter has the priority. Refer to Figure 6 for details.
Figure 6. Power Source Selection
During a charge cycle if the battery voltage is below the V
(LOWV)
threshold, the bq2501x applies a precharge
current, I
O(PRECHG)
, to the battery. This feature revives deeply discharged cells. The resistor connected between
the ISET1 and VSS pins, R
SET
, determines the precharge rate. The V
(PRECHG)
and K
(SET)
parameters are
specified in the specifications table.
The bq2501x activates a safety timer, t
(PRECHG)
, during the conditioning phase. If V
(LOWV)
threshold is not reached
within the timer period, the bq2501x turns off the charger and enunciates FAULT on the STAT1 and STAT2 pins.
Please refer to Timer Fault Recovery section for additional details.
The bq2501x offers on-chip current regulation with programmable set point. The resistor connected between the
ISET1 and VSS pins, R
SET
, determines the charge rate. The V
(SET)
and K
(SET)
parameters are specified in the
specifications table.
When charging from a USB port, the host controller has the option of selecting either 100 mA or 500 mA charge
rate using the ISET2 pin. A low-level signal sets the current at 100 mA and a high-level signal sets the current at
500 mA. A high-Z input disables USB charging.
The voltage regulation feedback is through the BAT/OUT pin. This input is tied directly to the positive side of the
battery pack. The bq2501x monitors the battery-pack voltage between the BAT/OUT and VSS pins. When the
battery voltage rises to V
O(REG)
threshold, the voltage regulation phase begins and the charging current begins to
taper down.
As a safety backup, the bq2501x also monitors the charge time in the charge mode. If taper threshold is not
detected within this time period, t
(CHG)
, the bq2501x turns off the charger and enunciates FAULT on the STAT1
and STAT2 pins. Please refer to section titled Timer Fault Recoverysection for additional details.
The bq2501x monitors the charging current during the voltage regulation phase. Once the taper threshold,
I
(TAPER)
, is detected the bq2501x initiates the taper timer, t
(TAPER)
. Charge is terminated after the timer expires.
The resistor connected between the ISET1 and VSS pins, R
SET
, determines the taper detection level. The
V
(TAPER)
and K
(SET)
parameters are specified in the specifications table. Note that this applies to both AC and
USB charging.
Copyright © 2004 – 2007, Texas Instruments Incorporated Submit Documentation Feedback 11
Product Folder Link(s): bq25010 bq25011 bq25012