BQ2000 Datasheet, PDF (10/18 Pages) Texas Instruments – Programmable Multi-Chemistry Fast-Charge Management IC

bq2000
Temperature
VTS > VLTF
VHTF < VTS < VLTF
VTS < VHTF
VTS < VTCO
Table 4. Temperature-Monitoring Conditions
Condition
Action
Cold battery—checked at all times
Suspends fast charge or top-off and timer
Allows trickle charge—LED flashes at 1Hz rate
during pre-charge qualification and fast charge
Optimal operating range
Allows charging
Hot battery—checked during charge quali-
fication and top-off and trickle-charge
Suspends fast-charge initiation, does not allow
trickle charge—LED flashes at 1Hz rate during
pre-charge qualification and fast charge
Battery exceeding maximum allowable
temperature—checked at all times
Terminates fast charge or top-off
n High-temperature fault voltage: VHTF = 0.25 ∗ VCC This
voltage corresponds to the temperature (HTF) at which
fast charging is allowed to begin.
n Low-temperature fault voltage: VLTF = 0.5 ∗ VCC
This voltage corresponds to the minimum temperature
(LTF) at which fast charging or top-off is allowed. If the
voltage on pin TS rises above VLTF, the bq2000
suspends fast charge or top-off but does not terminate
charge. When the voltage falls back below VLTF, fast
charge or top-off resumes from the point where
suspended. Trickle-charge is allowed during this
condition.
Table 4 summarizes these various conditions.
Sleep Mode
The bq2000 features a sleep mode for low power con-
sumption. This mode is enabled when the voltage at pin
BAT is above the low-power-mode threshold, VSLP. Dur-
ing sleep mode, the bq2000 shuts down all internal cir-
cuits, drives the LED output to high-impedance state,
and drives pin MOD to low. Restoring BAT below the
VMCV threshold initiates the IC and starts a fast-charge
cycle.
Charge Status Display
The charge status is indicated by open-drain output
LED. Table 5 summarizes the display output of the
bq2000.
Table 5. Charge Status Display
Charge Action State
Battery absent
Pre-charge qualification
Trickle charge (before fast charge)
Fast charging
Top-off or trickle (after fast charge,
NiCd, NiMH only)
Charge complete
Sleep mode
Charge suspended (VTS > VLTF)
LED Status
High impedance
1Hz flash
1Hz flash
Low
High impedance
High impedance
High impedance
1Hz flash
BAT-
R_f
RSNS
Power Supply ground
bq2000 ground
1 _SNS
C_f
2 _VSS
bq2000
2000CS.eps
Figure 9. Current-Sensing Circuit
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