L6460 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6460' PDF : 139 Pages View PDF
L6460
10 Power saving modes
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 * IV3v3.
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
VSupplyInt
VGPIOSpi
StdByMode
3.3 V
0
1.9 V
1
V3v3
+
Regulator
-
GPIO6
External
connection
3.3V
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.
Doc ID 17713 Rev 1
45/139
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