BQ25100_15 Datasheet, PDF (24/32 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
Typical Application - Charger Application Design Example (continued)
VIN 2 V/div
VTS 500 mV/div
IOUT 60 mA/div
VIN 2 V/div
VISET 2 V/div
ILOAD 70 mA/div
VISET 1 V/div
t-time – 50 ms/div
IOUT 70 mA/div
t-time – 10 ms/div
90-mA Load, 120-mA IOUT
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Figure 26. TS Enable and Disable
Figure 27. Power Up
10 Power Supply Recommendations
10.1 Leakage Current Effects on Battery Capacity
To determine how fast a leakage current on the battery will discharge the battery is an easy calculation. The time
from full to discharge can be calculated by dividing the Amp-Hour Capacity of the battery by the leakage current.
For a 0.1-AHr battery and a 75-nA leakage current (100mAHr/75nA = 250000 Hours), it would take 1333k hours
or 152 years to discharge. In reality the self discharge of the cell would be much faster so the 75-nA leakage
would be considered negligible.
11 Layout
11.1 Layout Guidelines
To obtain optimal performance, the decoupling capacitor from IN to GND and the output filter capacitors from
OUT to GND should be placed as close as possible to the bq2510x, with short trace runs to both IN, OUT and
GND.
• All low-current GND connections should be kept separate from the high-current charge or discharge paths
from the battery. Use a single-point ground technique incorporating both the small signal ground path and the
power ground path.
• The high current charge paths into IN pin and from the OUT pin must be sized appropriately for the maximum
charge current in order to avoid voltage drops in these traces
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