L6460 datasheet(46/139 Pages) STMICROELECTRONICS

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Power saving modes

L6460

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Doc ID 17713 Rev 1

10.2

Hibernate mode

L6460’s hibernate mode allows the firmware to switch off some (or all) selected System

Regulators leaving in on state only those necessary to resume L6460 to operative condition

when waked-up by an external signal.

Hibernate mode is selected when the firmware writes the command word in the

HibernateCmd register. When in hibernate mode L6460 will force regulators in the state

(on/off) selected by the firmware by writing in the HibernateCmd register and will force

nRESET pin low.

The exiting from hibernate mode is achieved by forcing at low level nAWAKE pin (or GPIO5

pin if L6460 is in Slave mode); L6460 will also exit from hibernate mode if an undervoltage

event happens on VSupply, VSupplyInt, VPump or V3v3.

When the exit from hibernate mode is due to an external command, L6460 sets to ‘1’ the bit

HibModeLth in the HibernateStatus register.

10.3

Low power mode

When in normal operating mode, the microcontroller can place L6460 in “Low Power mode”.

In this condition L6460 sets all bridges outputs in high impedance, powers down all

regulators (including system regulators and charge pump) and disables almost all its circuits

including internal clock reducing as much as possible power consumption.

The only circuits that remain active are:

–V3V3 internal regulator.

–

nAWAKE pin current pull-up.

–

nRESET pin that will be pulled low.

–

POR circuit.

The entering in low power mode is obtained in different ways depending if L6460 is

configured as slave device or not. When L6460 is configured as slave device the low power

mode is directly controlled by nAWAKE pin that acts as an enable: if this pin is low for a time

longer then tAWAKEFILT, Low Power mode is entered; if this pin is high L6460 exits from Low

Power mode.

In all other start-up configurations, Low Power mode is entered by writing a Low Power

mode command in the PowerModeControl register; once L6460 is in Low Power mode it

starts checking the nAWAKE pin status: if it is found low for a time longer than tAWAKEFILT,

L6460 exits from Low Power mode and restarts its startup sequence. When the nAWAKE

pin is externally pulled low, the “AWAKE” event is stored and it is readable through SPI.

L6460 will also exit from Low Power mode if a POR event is found.

Note:

When in “Low power mode” VSupply is monitored only for its power on reset level.

10.4

nAWAKE pin

At the start up, before L6460 has identified the required operation mode (see Chapter 8), a

current sink IINP is always active to pull down nAWAKE pin. As soon as the operation mode

(basic, slave, master or single device) is detected, the functionality of nAWAKE pin will be

different.

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