BQ24030_07 Datasheet, PDF (25/38 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINY)

bq24030, bq24031, bq24032A
bq24035, bq24038
www.ti.com
SLUS618F – AUGUST 2004 – REVISED NOVEMBER 2006
PG Output (Power Good), bq24038
The open-drain pin PG indicates when either the AC adapter or USB port is present and above the battery
voltage. This output is turned off in sleep mode (open drain). The PG pin can be used to drive a LED or
communicate with the host processor.
CE Input (Chip Enable)
The CE (chip enable) digital input is used to disable or enable the bqTINY III-series. A high-level signal on this
pin enables the chip, and a low-level signal disables the device and initiates the standby mode. The bqTINY
III-series enters the low-power standby mode when the CE input is low with either AC or USB present. In this
suspend mode, internal power FETs Q1 and Q3 (see Figure 4) are turned off; the battery (BAT pin) is used to
power the system via Q2 and the OUT pin which also powers the LDO. This feature is designed to limit the
power drawn from the input supplies (such as USB suspend mode).
VBSEL Input (Battery Voltage Selection), bq24038
The VBSEL (battery voltage select) digital input pin can be used to set the charge voltage to 4.2 V typical
(VBSEL = low) or 4.36 V typical (VBSEL = high). If VBSEL is left open, an internal current source pulldown
ensures that the charge voltage is set to 4.2 V typical.
Charge Disable Functions
The DPPM input can be used to disable the charge process. This can be accomplished by floating the DPPM
mode. Note that this applies to both AC and USB charging.
Timer Fault Recovery
As shown in Figure 3, bqTINY III-series provides a recovery method to deal with timer fault conditions. The
following summarizes this method:
Condition 1: Charge voltage above recharge threshold (V_(RCH)) and timeout fault occurs.
Recovery Method: bqTINY III-series waits for the battery voltage to fall below the recharge threshold. This
could happen as a result of a load on the battery, self-discharge, or battery removal. Once the battery falls below
the recharge threshold, the bqTINY III-series clears the fault and starts a new charge cycle. A POR or CE toggle
also clears the fault.
Condition 2: Charge voltage below recharge threshold (V_(RCH)) and timeout fault occurs.
Recovery Method: Under this scenario, the bqTINY III-series applies the I_(FAULT) current. This small current is
used to detect a battery removal condition and remains on as long as the battery voltage stays below the
recharge threshold. If the battery voltage goes above the recharge threshold, then the bqTINY III-series disables
the I_(FAULT) current and executes the recovery method described for condition 1. Once the battery falls below the
recharge threshold, the bqTINY III-series clears the fault and starts a new charge cycle. A POR or CE toggle
also clears the fault.
Short-Circuit Recovery
The output can experience two types of short-circuit protection, one associated with the input and one with the
battery.
If the output drops below ~1 V, an output short-circuit condition is declared and the input FETs (AC and USB)
are turned off. To recover from this state, a 500-Ω pullup resistor from each input is applied (switched) to the
output. To recover, the load on the output has to be reduced {Rload > 1 V × 500 Ω/ (Vin–Vout)} such that the
pullup resistor is able to lift the output voltage above 1 V, for the input FETs to be turned back on.
If the output drops 200 mV below the battery voltage, the battery FET is considered in short circuit and the
battery FET turns off. To recover from this state, there is a 10-mA ±8 mA current source from the battery to the
output. Once the output load is reduced, such that the current source can pick up the output within 200 mV of
the battery, the FET turns back on (As Vout increases in voltage the current source's drive drops toward 2 mA).
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