AS3517H-ECTP datasheet(40/94 Pages) AMSCO

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AS3517 V17

Data Sheet, Confidential

www.austriamicrosystems.com

9.2.3

Charger

General

This block can be used to charge a 4V Li-Io accumulator. It supports constant current and constant voltage charging modes with

adjustable charging currents (50 to 400mA) and maximum charging voltage (3.9 to 4.25V).

Figure 24 Charger States

Trickle Charge

If BVDD is below 3V in systems where the battery is not separated from BVDD, the charger goes automatically in trickle charge mode with

50mA charging current and 3.9V endpoint voltage. In this mode charging current and voltage are not precise, but provide a charger

function also for deep discharged batteries. The temperature supervision is not enabled in trickle charge mode.

As soon as BVDD reaches 3V the AFE switches on and starts-up the regulators with the power-up sequence selected by pins VPRG1 and

VPRG2. Afterwards the CPU can set the modes and the charging currents via the 2-wire serial interface.

If the battery (CHGOUT) voltage is below 2.9V the charging current cannot be set higher than 50mA, also when using a battery separation

circuit to supply the AFE (BVDD) from USB or another voltage source.

Temperature Supervision

This charger block also features a 15uA supply for an external 100k NTC resistor to measure the battery temperature while charging. If

the temperature is too high (>45°C), an interrupt can be generated. If the battery temperature drops below 42°C the charger will start

charging again. The temperature supervision is not enabled in trickle charge mode.

If the NTC resistor does not have 100kΩ its value can be corrected with a resistor in series or in parallel.

Revision 1v3

- 93

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