BQ24700 Datasheet, PDF (2/29 Pages) Texas Instruments – NOTEBOOK PC BATTERY CHARGE CONTROLLER AND SELECTOR WITH DPM

bq24700, bq24701
ą
NOTEBOOK PC BATTERY CHARGE CONTROLLER
AND SELECTOR WITH DPM
SLUS452B – APRIL 2001 – REVISED NOVEMBER 2002
description
The bq24700/bq24701 is a highly integrated battery charge controller and selector tailored for the notebook and
sub-notebook PC applications.
The bq24700/bq24701 uses dynamic power management (DPM) to minimize battery charge time by
maximizing use of available wall-adapter power. This is achieved by dynamically adjusting the battery charge
current based on the total system (adapter) current.
The bq24700/bq24701 uses a fixed frequency, pulse width modulator (PWM) to accurately control battery
charge current and voltage. Charge current limits can be programmed from a keyboard controller DAC or by
external resistor dividers from the precision 5-V, ±0.6%, externally bypassed voltage reference (VREF),
supplied by the bq24700/bq24701.
The battery voltage limit can be programmed by using the internal 1.25-V, ±0.5% precision reference, making
it suitable for the critical charging demands of lithium-ion cells. Also, the bq24700/bq24701 provides an option
to override the precision 1.25-V reference and drive the error amplifier either directly from an external reference
or from a resistor divider off the 5 V supplied by the integrated circuit.
The selector function allows the manual selection of the system power source, battery or wall-adapter power.
The bq24700 supports battery-conditioning and battery-lean cycles through the ACSEL function. The ACSEL
function allows manual selection of the battery or wall power as the main system power. It also provides
autonomous switching to the remaining source (battery or ac power) should the selected system power source
terminate (refer to Table 1 for the differences between the bq24700 and the bq24701). The bq24700/bq24701
also provides an alarm function to indicate a depleted battery condition.
The bq24700/bq24701 PWM controller is ideally suited for operation in a buck converter for applications when
the wall-adapter voltage is greater than the battery voltage.
Condition
–40 C TA 85 C
Battery as Power Source
Battery removal
Battery reinserted
ac as Power Source
AC removal
AC reinserted
Depleted Battery Condition
Battery as power source
AC as power source
ALARM Signal Active
AVAILABLE OPTIONS
Selector Operation
bq24700PW
bq24701PW
Automatically selects ac
Selection based on selector inputs
Automatically selects ac
Selection based on selector inputs
Automatically selects battery
Selection based on selector inputs
Automatically selects battery
Selection based on selector inputs
Sends ALARM signal
Sends ALARM signal
Automatically selects ac
Sends ALARM signal
Sends ALARM signal
Depleted battery condition
Depleted battery condition
Selector inputs do not match selector outputs
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