BQ25101H_15 Datasheet, PDF (23/32 Pages) Texas Instruments – bq2510x 250-mA Single Cell Li-Ion Battery Chargers, 1-mA Termination, 75-nA Battery Leakage

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bq25100, bq25101, bq25100A, bq25100H, bq25101H, bq25100L
SLUSBV8C – AUGUST 2014 – REVISED NOVEMBER 2014
Typical Application - Charger Application Design Example (continued)
9.2.2.1 Calculations
9.2.2.1.1 Program the Fast Charge Current, ISET:
R_ISET = [K_(ISET) / I_(OUT)]
from electrical characteristics table. . . K_(SET) = 135 AΩ
R_ISET = [135 AΩ/0.04 A] = 3.4 kΩ
Selecting the closest standard value, use a 3.4-kΩ resistor between ISET and Vss.
9.2.2.1.2 Program the Termination Current Threshold, ITERM:
R_PRE-TERM = K_(TERM) × %_IOUT-FC
R_PRE-TERM = 600 Ω/% × 10% = 6 kΩ
Selecting the closest standard value, use a 6-kΩ resistor between PRETERM and Vss.
One can arrive at the same value by using 20% for a pre-charge value (factor of 2 difference).
R_PRE-TERM = K_(PRE-CHG) × %_IOUT-FC
R_PRE-TERM = 300 Ω/% × 20%= 6 kΩ
9.2.2.1.3 TS Function
Use a 10-k NTC thermistor in the battery pack (103AT).
To Disable the temp sense function, use a fixed 10-kΩ resistor between the TS and VSS.
9.2.2.1.4 Selecting IN and OUT Pin Capacitors
In most applications, all that is needed is a high-frequency decoupling capacitor (ceramic) on the power pin, input
and output pins. Using the values shown on the application diagram is recommended. After evaluation of these
voltage signals with real system operational conditions, one can determine if capacitance values can be adjusted
toward the minimum recommended values (DC load application) or higher values for fast, high amplitude, pulsed
load applications. Note if designed for high input voltage sources (bad adaptors or wrong adaptors), the capacitor
needs to be rated appropriately. Ceramic capacitors are tested to 2x their rated values so a 16-V capacitor may
be adequate for a 30-V transient (verify tested rating with capacitor manufacturer).
9.2.3 bq25100 Application Performance Plots
VIN
VIN 2 V/div
2 V/div
VOUT 2 V/div
Hot Plug
IOUT 60 mA/div
VISET 1 V/div
t-time – 20 ms/div
VOUT 2 V/div
IOUT 60 mA/div
VISET 1 V/div
V_IN 0 V -5 V-7 V-5 V
t-time – 50 ms/div
Figure 24. OVP 7-V Adaptor
Figure 25. OVP from Normal Power-Up Operation
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