DA9021 datasheet(89/142 Pages) DIALOG

89 / 142 page

DA9021/22

System PMIC with high efficiency USB power manager

Datasheet

Revision 2.5

17-Feb-2017

CFR0011-120-00 Rev 5

89 of 142

The operating mode of the buck converter is selected via the buck control register bits. The buck

converter can be forced to operate in either SYNCHRONOUS mode or SLEEP mode. Additionally

the buck converter has an AUTOMATIC mode where it will switch between SYNCHRONOUS and

SLEEP mode depending on the load current.

In SLEEP mode the buck converter works in PFM mode. An internal zero crossing comparator is

used to time the turn-off of the NFET, thereby removing the need for an external Schottky diode.

All buck converters can be controlled via an ID from the power manager sequencer. If enabled at

sequencer step 0 (bit DEF_SUPPLY) buck converters can be default enabled via OTP whenever the

sequencer passes step 0 (OTP default settings are used). To limit the battery rush current it is

recommended that not more than a single supply (including LDOs) is enabled at step 0 During

powering down supplies can be pre-configured with a new target value (Bxxx_CONF bit is set).

If Bxxx_CONF is asserted in parallel with BUCKx_EN, the supply enable is deferred until the

sequencer is processing the related ID. The output voltage and enable state will be kept unchanged

until the sequencer processes the related time slot/ID during powering down (ignoring any assertions

of VB_xxx_GO while Bxxx_CONF is high). When powering up from POWERDOWN mode

(processing time slots in domain SYSTEM) the sequencer will configure bucks with their default

voltage values from OTP and by that reset the BUCKxxx_CONF bits. The bucks can also be

enabled/disabled/configured via the power manager and HS-2-wire interface when the DA9021/22 is

in the ACTIVE state.

Voltage transitions on bucks including DVC will always be ramped. Disabled bucks BUCKCORE,

BUCKPRO and BUCKMEM can switch off their pull down resistor (required for usage in parallel to an

alternative supply).

NOTE

Powering down to RESET mode will automatically disable all buck converters.

The converter BUCKCORE can additionally be merged with BUCKPRO towards a single DC-DC

converter with a maximum output current of 1.4 A. The routing of the switcher output pins towards

the common inductor has to be symmetrical and the feedback signal VBUCKPRO should be

connected to GND (if PRO_PD_DIS is asserted BUCKCOREORE can alternatively be connected to

VBUCKCORE). The inductor and the output capacitor have to be selected according to the intended

increased output current.

NOTE

The configuration controls of BUCKPRO are automatically disabled by asserting the bit BUCK_MERGE and the

selected current limits of BUCKCORE will be automatically doubled

DA9021 Datasheet(PDF) 89 Page - Dialog Semiconductor