Datasheet

bq24030, bq24031
bq24032A, bq24035, bq24038
www.ti.com ............................................................................................................................................... SLUS618H –AUGUST 2004–REVISED OCTOBER 2009
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.
DPPM Used As A Charge Disable Function
The DPPM pin can be used to disable the charge process. The DPPM pin has an output current source that,
when used with a resistor, sets the DPPM threshold. If the chosen resistance is too high, then the "DPPM-OUT"
voltage is programmed higher than the OUT pin regulation voltage and the part is put in DPPM mode. In this
mode the charging current is reduced until the OUT pin recovers to the DPPM_OUT threshold. Since the OUT
pin is in voltage regulation (below the DPPM-OUT threshold) it does not increase in amplitude, and the charge
current turns completely off. In DPPM mode the charge termination is diabled.
Note that the OUT pin regulates at 4.4V ±0.1V, with an adaptor input, on the bq24032A/bq24038 ICs, is switched
straight through on the bq24030/5 ICs (up to 6V); and, on USB inputs (all ICs) is switched straight through from
the USB input to the OUT pin.
If the DPPM pin is floated (resistor disconnected) then the DPPM pin will be driven high and the charge current
will go to zero. Note that this applies to both AC and USB charging. Another way to disable the charging is to
externally drive the DPPM pin high (to the OUT pin voltage).
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.
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Product Folder Link(s): bq24030, bq24031 bq24032A, bq24035, bq24038