BQ24232H_15 Datasheet, PDF(17/42 Page) Texas Instruments – bq2423xx USB-Friendly Lithium-Ion Battery Charger and Power-Path Management IC

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BQ24232H_15 Datasheet, PDF (17/42 Pages) Texas Instruments – bq2423xx USB-Friendly Lithium-Ion Battery Charger and Power-Path Management IC

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bq24230H, bq24232H

SLUSBI8A â JANUARY 2014 â REVISED DECEMBER 2014

9.3.3.2 Input Source Not Connected

When no source is connected to the IN input, OUT is powered strictly from the battery. During this mode, the

current into OUT is unregulated, similar to Battery Supplement Mode; however, the short-circuit circuitry is active.

If the OUT voltage falls below the BAT voltage by 250 mV for longer than tDGL(SC2), OUT is turned off. The short-

circuit recovery timer then starts counting. After tREC(SC2), OUT turns on and attempts to restart. If the short-circuit

remains, OUT is turned off and the counter restarts. This ON/OFF cycle continues until the overload condition is

removed.

9.3.4 Battery Charging

Set CE low to initiate battery charging. First, the device checks for a short circuit on the BAT pin by sourcing

IBAT(SC) to the battery and monitoring the voltage. When the BAT voltage exceeds VBAT(SC), the battery charging

continues. The battery is charged in three phases: conditioning precharge, constant-current fast charge (current

regulation), and a constant-voltage tapering (voltage regulation). In all charge phases, an internal control loop

monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is

exceeded.

Figure 14 illustrates a normal Li-ion charge cycle using the bq2423xH:

PRECHARGE

CC FAST CHARGE

CV TAPER

DONE

VBAT(REG)

IO(CHG)

Battery Current

VLOWV

I(PRECHG)

I(TERM)

Battery Voltage

CHG = Hi-z

Figure 14. Normal Li-ion Charge Cycle

In the precharge phase, the battery is charged with the precharge current (IPRECHG). Once the battery voltage

crosses the VLOWV threshold, the battery is charged with the fast-charge current (ICHG). As the battery voltage

reaches VBAT(REG), the battery is held at a constant voltage of VBAT(REG) and the charge current tapers off as the

battery approaches full charge. When the battery current reaches ITERM, the CHG pin indicates charging done by

going high impedance.

IPRECHG = KPRECHG/RISET

(1)

Termination detection is disabled whenever the charge rate is reduced because of the actions of the thermal

loop, the DPPM loop, or the VIN(LOW) loop.

The value of the fast-charge current is set by the resistor connected from the ISET pin to VSS, and is given by

Equation 2:

ICHG = KISET/RISET

(2)

Product Folder Links: bq24230H bq24232H

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