BQ25101H_15 Datasheet, PDF (12/32 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
8 Detailed Description
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8.1 Overview
The bq2510x is a highly integrated family of single cell Li-Ion and Li-Pol chargers. The charger can be used to
charge a battery, power a system or both. The charger has three phases of charging: pre-charge to recover a
fully discharged battery, fast-charge constant current to supply the charge safely and voltage regulation to safely
reach full capacity. The charger is very flexible, allowing programming of the fast-charge current and Pre-
charge/Termination Current. This charger is designed to work with a USB connection (100-mA limit) or Adaptor
(DC output). The charger also checks to see if a battery is present.
The charger also comes with a full set of safety features: JEITA Temperature Standard
(bq25100/01/100H/101H), Over-Voltage Protection, DPM-IN, Safety Timers, and ISET short protection. All of
these features and more are described in detail below.
The charger is designed for a single power path from the input to the output to charge a single cell Li-Ion or
Li-Pol battery pack. Upon application of a 5-V DC power source the ISET and OUT short checks are performed
to assure a proper charge cycle.
If the battery voltage is below the LOWV threshold, the battery is considered discharged and a preconditioning
cycle begins. The amount of precharge current can be programmed using the PRE-TERM pin which programs a
percent of fast charge current (10 to 100%) as the precharge current. This feature is useful when the system load
is connected across the battery “stealing” the battery current. The precharge current can be set higher to account
for the system loading while allowing the battery to be properly conditioned. The PRE-TERM pin is a dual
function pin which sets the precharge current level and the termination threshold level. The termination "current
threshold" is always half of the precharge programmed current level.
Once the battery voltage has charged to the VLOWV threshold, fast charge is initiated and the fast charge
current is applied. The fast charge constant current is programmed using the ISET pin. The constant current
provides the bulk of the charge. Power dissipation in the IC is greatest in fast charge with a lower battery voltage.
If the IC reaches 125°C, the IC enters thermal regulation, slows the timer clock by half, and reduces the charge
current as needed to keep the temperature from rising any further. Figure 19 shows the charging profile with
thermal regulation. Typically under normal operating conditions, the IC’s junction temperature is less than 125°C
and thermal regulation is not entered.
Once the cell has charged to the regulation voltage the voltage loop takes control and holds the battery at the
regulation voltage until the current tapers to the termination threshold. The termination can be disabled if desired.
Further details are described in the Operating Modes section.
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