BQ2003STR datasheet(5/20 Pages) TI2

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the allowed limits. If the voltage is too high, the chip

goes to the battery absent state and waits until a new

charge cycle is started.

Fast charge continues until termination by one or more

of the five possible termination conditions:

n Delta temperature/delta time (

∆T/∆t)

n Negative delta voltage (-

∆V)

n Maximum voltage

n Maximum temperature

n Maximum time

∆V Termination

If the DVEN input is high, the bq2003 samples the volt-

age at the BAT pin once every 34s. If VCELL is lower

than any previously measured value by 12mV

±4mV,

fast charge is terminated. The -

∆V test is valid in the

range VMCV - (0.2

∗ VCC)<VCELL <VMCV.

Voltage Sampling

Each sample is an average of 16 voltage measurements

taken 57

µs apart. The resulting sample period (18.18ms)

filters out harmonics around 55Hz. This technique mini-

mizes 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%.

Voltage Termination Hold-off

A hold-off period occurs at the start of fast charging.

During the hold-off period, -

∆V termination is disabled.

This avoids premature termination on the voltage spikes

sometimes produced by older batteries when fast-charge

current is first applied.

∆T/∆t, maximum voltage and

maximum temperature terminations are not affected by

the hold-off period.

∆T/∆t Termination

The bq2003 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

taken 57

µs apart. The resulting sample period

(18.18ms) filters out harmonics around 55Hz. 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%.

Maximum Voltage, Temperature, and Time

Anytime VCELL rises above VMCV, CHG goes high (the LED

goes off) immediately. If the bq2003 is not in the voltage

hold-off period, fast charging ceases if VCELL remains above

MCV for a minimum of tMCV.If VCELL then falls back be-

low VMCV before 1.5tMCV

±50ms, the chip transitions to the

Charge Complete state (maximum voltage termination). If

VCELL remains above VMCV beyond 1.5tMCV, the bq2003

transitions to the Battery Absent state (battery removal).

See Figure 3.

If the bq2003 is in the voltage hold-off period when

VCELL rises above VMCV, the LED goes out but fast

charging continues until the expiration of the hold-off

period. Temperature sampling continues during the

hold-off period as well. If a new battery is inserted be-

fore the hold-off period expires, it continues in the fast

charge cycle started by its predecessor. No precharge

qualification is performed, and a temperature sample

bq2003

Corresponding

Fast-Charge Rate

TM1

TM2

Typical Fast Charge

and Top-Off

Time Limits

Typical -

∆V/MCV

Hold-Off

Time (seconds)

Top-Off

Rate

C/4

Low

360

137

Disabled

C/2

Float

Low

180

820

Disabled

High

Low

410

Disabled

Low

Float

200

Disabled

Float

100

Disabled

C/2

High

Float

180

820

C/16

Low

High

410

C/8

Float

High

200

C/4

High

100

C/2

Note:

Typical conditions = 25°C, VCC = 5.0V.

Table 2. Fast-Charge Safety Time/Hold-Off/Top-Off Table

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