DA9021 datasheet(108/142 Pages) DIALOG

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DA9021/22

System PMIC with high efficiency USB power manager

Datasheet

Revision 2.5

17-Feb-2017

CFR0011-120-00 Rev 5

108 of 142

19.7 Dynamic charging current control (DCCC) and active-diode

If the combination of the system load plus the battery charging current (pre-charge or fast linear

charging) exceeds the charger buck output current (which is limited by the current limitation of the

buck) into the VDDOUT node, then the output voltage on VDDOUT will start to drop down to VBAT

(which automatically reduces the charging current).

When the VDDOUT voltage drops to 3.6 V, and the charger buck is still in current limit, the charging

current to the battery will be reduced until it reaches zero or the buck runs below its current limit.

Once the VDDOUT is > 3.6 V or the buck runs below its current limit, the charging will be increased

until it reaches the programmed setting.

The battery charging control includes an active-diode circuit that will automatically provide current to

the system if the VDDOUT voltage falls below the VBAT voltage. If large currents or very low

resistance in series with the battery output is required the path can be extended by an external power

FET using the external active-diode controller.

100

200

300

400

IOUT

IVBUS

500

600

ICHG_BAT

100

200

300

400

500

IOUT [mA]

600

Example of DCCC & active diode operation in USB high power mode

extra current supplied

by active diode

Figure 45: DCCC & active diode operation

19.8 Programmable charge termination by time

The battery charger block will provide a safety timer controlling the maximum time allowed for battery

charging. The charge timer is programmable through the power manager bus. The total charge time

is defined as the time from when the battery charging was enabled (both for FAST and PRE-

CHARGE mode charging).

During FAST charge mode the time is dynamically extended whenever the current into the battery is

automatically reduced from DCCC or thermal regulation towards less than (for example) 50 % of the

configured maximum charge current. This change in charge time is inversely proportional to the

change in charge current. The dynamic safety timer is limited to eight times the programmed clock

period and can alternatively be configured towards a fixed timer. If the timer expires (reaches zero)

an interrupt request is issued and charging is disabled.

DA9021 Datasheet(PDF) 108 Page - Dialog Semiconductor

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