BQ2406X Datasheet, PDF (14/31 Pages) Texas Instruments – 1A SINGLE-CHIP Li-Ion/Li-Pol CHARGE MANAGEMENT IC WITH THERMAL REGULATION

bq2406x
SLUS689 – JUNE 2006
www.ti.com
V_CC
V_C(TS2)
0.6* V_CC
V_C(TS1)
0.3* V_CC
Charge Suspend
Normal Temperature
Range
Charge Suspend
Figure 5. Battery Temperature Qualification With NTC Thermistor
The external resistors R_T1 and R_T2 (see application diagram) enable selecting a temperature window. If R_TC and
R_TH are the thermistor impedances for the Cold and Hot thresholds the values for R_T1 and R_T2 can be calculated
as follows, for a NTC (negative temperature coefficient) thermistor:
R_T1
+
ǒ₃
ǒ₅
R
ǒ_RTC
R_TC^Ǔ
* R_TH^ǓǓ
(1)
R_T2 + _ƪǒ2
ǒ_{5 R RTC}Ǔ
R_TC^Ǔ * ^ǒ7 R_TH^Ǔƫ
(2)
Applying a constant voltage between the V(TS1) and V(TS2) thresholds to pin TS disables the temperature
sensing feature.
INPUT OVER-VOLTAGE DETECTION, POWER GOOD STATUS OUTPUT
The input power detection status for pin IN is shown at the open collector output pin PG.
Table 2. Input Power Detection Status
INPUT POWER DETECTION (IN)
NOT DETECTED
DETECTED, NO OVER-VOLTAGE
DETECTED, OVER-VOLTAGE
PG STATE
High impedance
LO
High impedance
The bq2406x detects an input over-voltage when V(IN) > V_(OVP). When an over-voltage protection is detected the
charger function is turned off and the bq2460x is set to standby mode of operation. The OVP detection is not
latched, and the IC returns to normal operation when the fault condition is removed.
CHARGE STATUS OUTPUTS
The open-collector STAT1 and STAT2 outputs indicate various charger operations as shown in Table 3. These
status pins can be used to drive LEDs or communicate to the host processor. Note that OFF indicates the
open-collector transistor is turned off. When termination is disabled the Done state is not available; the status
LEDs indicate fast charge or pre-charge even if the charge current is lower than the termination detection
threshold.
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