BQ25100_15 Datasheet, PDF (18/32 Pages) Texas Instruments – bq2510x 250-mA Single Cell Li-Ion Battery Chargers, 1-mA Termination, 75-nA Battery Leakage

bq25100, bq25101, bq25100A, bq25100H, bq25101H, bq25100L
SLUSBV8C – AUGUST 2014 – REVISED NOVEMBER 2014
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Feature Description (continued)
The TS feature is implemented using an internal 50μA current source to bias the thermistor (designed for use
with a 10-k NTC β = 3370 (SEMITEC 103AT-2 or Mitsubishi TH05-3H103F) connected from the TS pin to V_SS. If
this feature is not needed, a fixed 10-k can be placed between TS and V_SS to allow normal operation. This may
be done if the host is monitoring the thermistor and then the host would determine when to pull the TS pin low to
disable charge.
The TS pin has two additional features, when the TS pin is pulled low or floated/driven high. A low disables
charge and a high puts the charger in TTDM.
Above 60°C (45°C for bq25100A) or below 0°C the charge is disabled. Once the thermistor reaches ≉–10°C the
TS current folds back to keep a cold thermistor (between –10°C and –50°C) from placing the IC in the TTDM
mode. If the TS pin is pulled low into disable mode, the current is reduce to ≉30 μA. Since the I_TS curent is fixed
along with the temperature thresholds, it is not possible to use thermistor values other than the 10-k NTC (at
25°C).
8.3.9 Timers
The pre-charge timer is set to 30 minutes. The pre-charge current, can be programmed to off-set any system
load, making sure that the 30 minutes is adequate.
The fast charge timer is fixed at 10 hours and can be increased real time by going into thermal regulation or IN-
DPM. The timer clock slows by a factor of 2, resulting in a clock than counts half as fast when in these modes. If
either the 30 minute or ten hour timer times out, the charging is terminated and for bq25101/1H the CHG pin
goes high impedance if not already in that state. The timer is reset by disabling the IC, cycling power or going
into and out of TTDM.
8.3.10 Termination
Once the OUT pin goes above VRCH, (reaches voltage regulation) and the current tapers down to the
termination threshold, a battery detect route is run to determine if the battery was removed or the battery is full. If
the battery is present, the charge current will terminate. If the battery was removed along with the thermistor,
then the TS pin is driven high and the charge enters TTDM. If the battery was removed and the TS pin is held in
the active region, then the battery detect routine will continue until a battery is inserted. The termination current
can be programmed down to 625 uA, however, the accuracy will reduce acoordingly when the termination
current is below 1 mA.
8.4 Device Functional Modes
8.4.1 Power-Down or Undervoltage Lockout (UVLO)
The bq2510x family is in power down mode if the IN pin voltage is less than UVLO. The part is considered
“dead” and all the pins are high impedance. Once the IN voltage rises above the UVLO threshold the IC will
enter Sleep Mode or Active mode depending on the OUT pin (battery) voltage.
8.4.2 Power-up
The IC is alive after the IN voltage ramps above UVLO (see sleep mode), resets all logic and timers, and starts
to perform many of the continuous monitoring routines. Typically the input voltage quickly rises through the
UVLO and sleep states where the IC declares power good, starts the qualification charge at 22 mA, sets the
charge current base on the ISET pin, and starts the safety timer.
8.4.3 Sleep Mode
If the IN pin voltage is between V_OUT+V_DT and UVLO, the charge current is disabled, the safety timer counting
stops (not reset). As the input voltage rises and the charger exits sleep mode, the safety timer continues to count
and the charge is enabled. See Figure 22.
8.4.4 New Charge Cycle
A new charge cycle is started when a good power source is applied, performing a chip disable/enable (TS pin),
exiting Termination and Timer Disable Mode (TTDM), detecting a battery insertion or the OUT voltage dropping
below the VRCH threshold.
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