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SLUS530H – SEPTEMBER 2002 – REVISED JUNE 2007
FUNCTIONAL DESCRIPTION (continued)
After charge termination, the bqTINY restarts the charge once the voltage on the BAT pin falls below the
V(RCH) threshold. This feature keeps the battery at full capacity at all times. See the
Battery Absent Detection
section
for additional details.
SLEEP MODE
The bqTINY enters the low-power sleep mode if the V
CC
is removed from the circuit (PG pin is high impedance).
This feature prevents draining the battery during the absence of V
CC
. The status pins do not function when in
sleep mode or when V
CC
< V
POR
and default to the OFF state.
CHARGE STATUS OUTPUTS
The open-collector STAT1 and STAT2 outputs indicate various charger operations as shown in the following
table. These status pins can be used to drive LEDs or communicate to the host processor. Note that OFF
indicates the open-collector transistor is turned off. When V
CC
< V
POR
or V
CC
< V
BAT
(Sleep Mode – PG OFF) the
STAT pins default to their OFF state. Note that this STAT1/STAT2 OFF/OFF state is shared by several
operating conditions. Monitoring IN, BAT, PG and TS, it is possible to decode the actual fault condition.
Table 1. Status Pins Summary
CHARGE STATE
Charge-in-progress
Charge done
Battery absent
Charge suspend (temperature)
Timer fault
Sleep mode
(1)
STAT1
ON
OFF
(1)
STAT2
OFF
ON
OFF
OFF
OFF means the open-collector output transistor on the STAT1 or
STAT2 pins is in an off state.
PG OUTPUT
The open-collector PG (power good) indicates when the ac adapter (i.e., V
CC
) is present. The PG bipolar
transistor turns ON when a valid V
CC
is detected. This output is turned off in the sleep mode. The PG pin can be
used to drive an LED or communicate to the host processor.
CE INPUT (CHARGE ENABLE)
The CE digital linput is used to disable or enable the charge process. A low-level signal on this pin enables the
charge and a high-level signal disables the charge. A high-to-low transition on this pin also resets all timers and
fault conditions and starts a new charge cycle.
TTE INPUT (TIMER AND TERMINATION ENABLE)
The TTE digital input is used to disable or enable the fast-charge timer and charge termination. A low-level
signal on this pin enables the fast-charge timer and termination and a high-level signal disables this feature. A
high-to-low transition on this pin also resets all timers.
THERMAL SHUTDOWN AND PROTECTION
The bqTINY monitors the junction temperature, T
J
, of the die and suspends charging if T
J
exceeds 155°C.
Charging resumes when T
J
falls below approximately 130°C.
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