AXP209 datasheet(20/45 Pages) ETC2

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AXP209

Enhanced single Cell Li-Battery and Power System Management IC

VTRGT

ICHRG

VTRKL

ITRKL

VTRGT = charge target voltage. The VTRGT is 4.2V by default, which can be set via a register (Refer to

“REG33H[6:5]”) . At the same time, AXP209 will automatically adjust the charge target voltage when

external power voltage is low.

VRCH = automatic recharge voltage. VRCH=VTRGT-0.1V

Charging current

The charge current is 500mAor 1200mA by default, which can be set by REG33H [3:0].

Charging Process

If the battery voltage is lower than 3.0V, the charger will automatically enter the pre-charge mode, with

charge current being 1/10 of the preset value. If the battery voltage is still below 3.0V 40 minutes later

(adjustable, see “REG34H”), the charger will automatically enter the battery activate mode. Refer to

“Battery Activate Mode” section for details.

Once the battery voltage exceeds 3.0V, the charger enters constant current mode. If the charge current

is below 65% of the preset value, the system will send IRQ17 to indicate that “drive ability of external

power is insufficient”, as a result, the charge current is lower than the preset value, which may lead to

longer charge time, so stronger power is preferred, or power-consuming functions should be disabled to

shorten the charge time.

When the battery voltage reaches the VTRGT, the charger will switch from the constant current mode to

constant voltage mode, and the charge current will taper off.

When the charge current is lower than 10% or 15% (adjustable, see register “REG33H”) of the preset

value, a charge cycle ends, and AXP202 will release IRQ18 while the CHGLED pin will stop indicating

the charging state. When the battery voltage is below VRCH again, the automatic charge will restart, and

IRQ17 will be issued.

Confidential

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