BQ24020 Datasheet, PDF (14/20 Pages) Texas Instruments – SINGLE-CHIP,LI-ION AND LI-POL CHARGER IC WITH AUTONOMOUS USB-PORT AND AC-ADAPTER SUPPLY MANAGEMENT

bq24020, bq24022, bq24023
bq24024, bq24025, bq24026
bq24027
SLUS549D – DECEMBER 2002 – REVISED MARCH 2006
www.ti.com
FUNCTIONAL DESCRIPTION (continued)
CHARGE STATUS OUTPUTS
The open-drain 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-drain transistor is turned off.
Table 1. Status Pins Summary⁽¹⁾
CHARGE STATE
Precharge in progress
Fast charge in progress
Charge done
Charge suspend (temperature)
Timer fault
Sleep mode
STAT1
ON
ON
OFF
OFF
OFF
OFF
(1) OFF means the open-drain output transistor on the STAT1 and STAT2 pins is in an off state.
STAT2
ON
OFF
ON
OFF
OFF
OFF
PG OUTPUT
The open-drain PG (power Good) indicates when the AC adapter is present. The output turns ON when a valid
voltage is detected. This output is turned off in the sleep mode. The PG pin can be used to drive an LED or to
communicate to the host processor.
CE INPUT (CHARGE ENABLE)
The CE digital input is used to disable or enable the charge process. A low-level signal on this pin enables the
charge. A high-level signal disables the charge, and places the device in a low-power mode. A high-to-low
transition on this pin also resets all timers and timer fault conditions. Note that this applies to both AC and USB
charging.
TTE INPUT (TIMER AND TERMINATION ENABLE)
The TTE digital input is used to disable or enable the fast-charge timer and charge-taper detection. A low-level
signal on this pin enables the fast-charge timer and taper timer, and a high-level signal disables this feature.
Note that this applies to both AC and USB charging.
THERMAL SHUTDOWN AND PROTECTION
The bqTINY-II monitors the junction temperature, T_J, and suspends charging if T_J exceeds T_(SHTDWN). Charging
resumes when T_J falls approximately 15°C below T_(SHTDWN).
TE INPUT (TIMER ENABLED)
The TE digital input is used to disable or enable the fast-charge timer. A low-level signal on this pin enables the
fast-charge timer and a high-level signal disables this feature.
Note that this applies to both AC and USB charging.
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