L6460 datasheet(45/139 Pages) STMICROELECTRONICS

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L6460

Power saving modes

Doc ID 17713 Rev 1

45/139

Power saving modes

Saving power is very important for today platforms: L6460 implements different functions to

achieve different levels of power saving. Sections here below describe these different power

saving modes.

10.1

Standby mode

Almost all low voltage circuitry inside L6460 are powered by V3v3 internal regulator; this

regulator is a linear regulator powered by VSupplyInt. This means that all the current provided

by V3v3 regulator is directly coming from VSupplyInt and therefore the total power

consumption is:

Low voltage power = VSupply* IV3v3.

because VSupplyInt is feeded by VSupply, directly or with a resistor in series.

This power could be reduced by using a switching buck regulator to supply V3v3: in this

case, assuming the buck regulator efficiency near to 100%, the dissipated power would

become:

Low voltage power

≈ 3.3V * I

V3v3.

To achieve this result there is the need to switch off the internal V3v3 linear regulator and to

use an additional pin to provide a 3.3 V supply to internal circuits. L6460 can do this by

using the low voltage switch implemented on GPIO6 pin. This switch internally connects

VGPIO_SPI voltage to GPIO6 output so, by externally connecting GPIO6 to V3v3 pin, the

VGPIO_SPI voltage can be provided to low voltage circuitry inside L6460.

Figure 7.

Standby mode function description

The StdByMode bit used to switch off V3v3 and switch on the power switch can be set to ‘1’

by writing the standby command in the StdByMode register. L6460 exits standby mode if a

reset event happens or “Low Power mode” is selected.

Because all internal low voltage circuitry powered by V3v3 are designed to work with a 3.3V

voltage rail, when the standby mode is used, VGPIO_SPI is requested to be at 3.3V.

3.3V

GPIO6

VGPIOSpi

VSupplyInt

V3v3

Regulator

StdByMode

3.3 V

1.9 V

External

connection

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