BQ24030-Q1 Datasheet, PDF (23/34 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC

bq24030-Q1
bq24031-Q1
www.ti.com.................................................................................................................................................... SLUS793B – APRIL 2008 – REVISED OCTOBER 2009
Chip Enable (CE) Input
The CE 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).
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 disabled.
Note that the OUT pin is switched straight through (up to 6 V) and, on USB inputs, is switched straight through
from the USB input to the OUT pin.
If the DPPM pin is floated (resistor disconnected), it is driven high and the charge current goes 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.
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 {R_load > 1 V × 500 Ω/ (V_IN – V_OUT)} 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 it 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).
If the short is removed and the minimum system load is still too large [R < (V_Bat – 200 mV / 2 mA)], the
short-circuit protection can be temporarily defeated. The battery short-circuit protection can be disabled
(recommended only for a short time) if the voltage on the DPPM pin is less than 1 V. Pulsing this pin below 1 V
for a few microseconds should be enough to recover.
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