DA9021 datasheet(105/142 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

105 of 142

VBUS_VLD

5.6V

VBUS

VBUS_PROT

4.4V

VBUS_SUSP_EN

Ext. PMOS

VBUS_OV

Figure 44: Charger detection

The charger initial insertion is detected when the voltage comparators indicate that VBUS_PROT is

still present after a debounce time of 10 ms. At this time the charger buck converter will be enabled

via a soft start up to the appropriate current limitation (see above) if the chargers attach comparator

flags with enough voltage headroom from VDDOUT to VCENTER to allow the buck converter to

operate. The battery is disconnected from VDDOUT as the charger supply takes over. This is done

by enabling an active diode function as part of the battery P-FET, giving a clean transfer of power.

The differential charger attach comparator (CHG_ATT) detects a typical drop of 100 mV across

VCENTER to VDDOUT and acts together with the charge detection comparators as an under voltage

lock out, which is performed in two phases. In the first phase a falling voltage at the charger input

towards VCH_THR will force the charger buck state machine to reduce the charger buck current

limitation step by step down to its minimum value. If the input voltage will not recover and the

CHG_ATT comparator flags a voltage drop from VCENTER to VDDOUT is below 85 mV, the charger

buck is disabled as soon the current limit reaches its minimum value. If the input voltage recovers,

the state machine starts increasing the current limit again until it reaches its programmed value using

a slow attach time.

If during normal operation the CHG_DET signals a valid input voltage, but the CHG_ATT comparator

flags a low drop across VCENTER to VDDOUT, the buck current limit is ramped down in the same

way as mentioned before. The charger buck will be disabled if the voltage drop across VCENTER to

VDDOUT does not rise towards a minimum of 100 mV.

NOTE

CHG_DET is VBUS_DET dependant.

19.3 VBUS overvoltage protection and USB suspend

DA9021/22 includes an overvoltage protection circuit that disconnects VBUS from the VBUS_PROT

input via the external PFETs whenever the VBUS voltage is above the VCHG_EXCESS threshold.

This circuit supports a USB low power SUSPEND mode, enabled via the control bit VBUS_SUSP,

where the VBUS_PROT path is switched off and the VDDOUT main supply is switched to the battery

disabling charging (similar to removing the VBUS supply).VBUS_SUSP is cleared when the USB

charger is removed.

The charger buck supports a BUS powered low current mode which is enabled via control bit

CHG_BUCK_LP. In this mode the charger buck is forced to a PFM mode to ensure the system is

backed up with minimum power dissipation when being supplied from an external supply. Charging

will be suspended, but with appropriate configurations of the regulators, power to for example, an idle

USB PHY can be supplied.

DA9021 Datasheet(PDF) 105 Page - Dialog Semiconductor

DA9021 Datasheet(HTML) 105 Page - Dialog Semiconductor

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