BQ2004E_07 Datasheet, PDF (5/19 Pages) Texas Instruments – Fast-Charge ICs

bq2004E/H
VSEL Input
Low
Float
High
Voltage Termination
Disabled
-∆V
PVD
Voltage Sampling
Each sample is an average of voltage measurements.
The IC takes 32 measurements in PVD mode and 16
measurements in -∆V mode. The resulting sample peri-
ods (9.17ms and 18.18ms, respectively) filter out har-
monics centered around 55Hz and 109Hz. This tech-
nique minimizes the effect of any AC line ripple that
may feed through the power supply from either 50Hz or
60Hz AC sources. Tolerance on all timing is ±16%.
Temperature and Voltage Termination
Hold-off
A hold-off period occurs at the start of fast charging.
During the hold-off period, -∆V and ∆T/∆t termination
are disabled. The MOD pin is enabled at a duty cycle of
260µs active for every 1820µs inactive. This modulation
results in an average rate 1/8th that of the fast charge
rate. This avoids premature termination on the voltage
spikes sometimes produced by older batteries when
fast-charge current is first applied. Maximum voltage
and maximum temperature terminations are not af-
fected by the hold-off period.
∆T/∆t Termination
The bq2004E/H samples at the voltage at the TS pin
every 34s, and compares it to the value measured two
samples earlier. If VTEMP has fallen 16mV ±4mV or
more, fast charge is terminated. The ∆T/∆t termination
test is valid only when VTCO < VTEMP < VLTF.
Temperature Sampling
Each sample is an average of 16 voltage measurements.
The resulting sample period (18.18ms) filters out har-
monics around 55Hz. This technique minimizes the ef-
fect of any AC line ripple that may feed through the
power supply from either 50Hz or 60Hz AC sources. Tol-
erance on all timing is ±16%.
Maximum Voltage, Temperature, and Time
Anytime VCELL rises above VMCV, the LEDs go off and cur-
rent flow into the battery ceases immediately. If VCELL
then falls back below VMCV before tMCV = 1.5s ±0.5s, the
chip transitions to the Charge Complete state (maximum
voltage termination). If VCELL remains above VMCV at the
expiration of tMCV, the bq2004E/H transitions to the Bat-
tery Absent state (battery removal). See Figure 3.
Maximum temperature termination occurs anytime
VTEMP falls below the temperature cutoff threshold
VTCO. Charge will also be terminated if VTEMP rises
above the low temperature fault threshold, VLTF, after
fast charge begins.
Table 1. Fast Charge Safety Time/Hold-Off/Top-Off Table
Corresponding
Fast-Charge
Rate
2004E 2004H _{TM1 TM2}
C/4
C/8 Low Low
C/2
C/4 Float Low
1C
C/2 High Low
2C
1C Low Float
4C
2C Float Float
C/2
C/4 High Float
1C
C/2 Low High
2C
1C Float High
4C
2C High High
Typical
Fast-Charge
Safety
Time (min)
2004E 2004H
325 650
154 325
77
154
39
77
19
39
154 325
77
154
39
77
19
39
Typical
PVD, -∆V
Hold-Off
Time (s)
2004E 2004H
Top-Off
Rate
2004E 2004H
Pulse-
Trickle
Rate
137 273
Disabled
Disabled
546 546
Disabled
C/512
273 546
Disabled
C/512
137 273
Disabled
C/512
68
137
Disabled
C/512
546 546 C/16 C/32 C/512
273 546 C/8 C/16 C/512
137 273 C/4 C/18 C/512
68
137 C/2
C/4
C/512
Pulse-
Trickle
Period (Hz)
2004E 2004H
Disabled
15
30
7.5
15
3.75 7.5
1.88 3.75
15
30
7.5
15
3.75 7.5
1.88 3.75
Note: Typical conditions = 25°C, VCC = 5.0V.
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