Datasheet

5
VSEL Input Voltage Termination
Low Disabled
Float
-∆V
High 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. Toleranceonalltimingis±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 V
TEMP
has fallen 16mV ±4mV or
more, fast charge is terminated. The ∆T/∆t termination
test is valid only when V
TCO
<V
TEMP
<V
LTF
.
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 V
CELL
rises above V
MCV,
the LEDs go off and cur
-
rent flow into the battery ceases immediately. If V
CELL
then falls back below V
MCV
before t
MCV
= 1.5s ±0.5s, the
chip transitions to the Charge Complete state (maximum
voltage termination). If V
CELL
remains above V
MCV
at the
expiration of t
MCV,
the bq2004E/H transitions to the Bat-
tery Absent state (battery removal). See Figure3.
Maximum temperature termination occurs anytime
V
TEMP
falls below the temperature cutoff threshold
V
TCO
. Charge will also be terminated if V
TEMP
rises
above the low temperature fault threshold, V
LTF
, after
fast charge begins.
Corresponding
Fast-Charge
Rate
TM1 TM2
Typical
Fast-Charge
Safety
Time (min)
Typical
PVD, -
∆
V
Hold-Off
Time (s)
Top-Off
Rate
Pulse-
Trickle
Rate
Pulse-
Trickle
Period (Hz)
2004E 2004H 2004E 2004H 2004E 2004H 2004E 2004H 2004E 2004H
C/4 C/8 Low Low 325 650 137 273 Disabled Disabled Disabled
C/2 C/4 Float Low 154 325 546 546 Disabled C/512 15 30
1C C/2 High Low 77 154 273 546 Disabled C/512 7.5 15
2C 1C Low Float 39 77 137 273 Disabled C/512 3.75 7.5
4C 2C Float Float 19 39 68 137 Disabled C/512 1.88 3.75
C/2 C/4 High Float 154 325 546 546 C/16 C/32 C/512 15 30
1C C/2 Low High 77 154 273 546 C/8 C/16 C/512 7.5 15
2C 1C Float High 39 77 137 273 C/4 C/18 C/512 3.75 7.5
4C 2C High High 19 39 68 137 C/2 C/4 C/512 1.88 3.75
Note: Typical conditions = 25°C, V
CC
= 5.0V.
Table 1. Fast Charge Safety Time/Hold-Off/Top-Off Table
bq2004E/H