POWER

ON

RESET

STANDBY

START UP

IDLE

SHUT

DOWN

LP8720

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SNVS575B – JULY 2008 – REVISED MAY 2013

LP8720 PIN DESCRIPTIONS(1) (continued)

Pin Number

Name

Type

Description

D3

DVS

DI

Dynamic Voltage Scaling.

When DVS=HI then Buck voltage set BUCK_V1 is in use.

When DVS=LO then Buck voltage set BUCK_V2 is in use.

Buck voltage set BUCK_V1 should be higher than Buck voltage set BUCK_V2.

If not in use then hard wire to VBATT or GND.

Device Description

Operation Modes

POWER-ON-RESET: After VBATT gets above POR higher threshold, the DEFSEL pin and IDSEL pin are read.

All internal registers of LP8720 then are reset to the default values; after that the LP8720 goes to

STANDBY mode. This process duration max is 500 µs.

STANDBY: In STANDBY mode only serial interface is working and all other PMU functions are disabled – PMU

is in low-power condition. In STANDBY mode the LP8720 can be (re)configured via Serial Interface.

STARTUP: STARTUP sequence is defined by registers contents. STARTUP sequence starts:

1) If rising edge on EN pin.

2) After cooling down from thermal shutdown event if EN = HI.

It is not recommended to write to LP8720 registers during startup. If doing so then current startup

sequence may become undefined.

IDLE: PMU will enter into IDLE mode (normal operating mode) after end of startup sequence. In IDLE mode all

LDO’s and BUCK can be enabled/disabled via Serial Interface. Also in IDLE mode LP8720 can be

(re)configured via Serial Interface.

SHUTDOWN: SHUTDOWN sequence is “reverse order of startup sequence,” and this is defined by registers

contents. SHUTDOWN starts:

1) If falling edge on EN pin.

2) If temperature exceeds thermal shutdown threshold TSD +160°C.

It is not recommended to write to LP8720 registers during SHUTDOWN. If doing so then current

SHUTDOWN sequence may become undefined.

Additional Functions

SLEEP: If sum of all LDOs' load currents and BUCK load current is no higher than 5 mA , the user can put PMU

to SLEEP. In SLEEP PMU GND current is minimized, and LDO’s and BUCK cannot be loaded with bigger

current.

There are 2 possibilities to use SLEEP:

1) Control via Serial Interface.

2) Control by DVS pin.

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