Datasheet

L6460 Power saving modes
Doc ID 17713 Rev 1 45/139
10 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 V
3v3
internal regulator; this
regulator is a linear regulator powered by V
SupplyInt.
This means that all the current provided
by V
3v3
regulator is directly coming from V
SupplyInt
and therefore the total power
consumption is:
Low voltage power = V
Supply
* I
V3v3
.
because V
SupplyInt
is feeded by V
Supply
, directly or with a resistor in series.
This power could be reduced by using a switching buck regulator to supply V
3v3
: 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 V
3v3
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
V
GPIO_SPI
voltage to GPIO6 output so, by externally connecting GPIO6 to V
3v3
pin, the
V
GPIO_SPI
voltage can be provided to low voltage circuitry inside L6460.
Figure 7. Standby mode function description
The StdByMode bit used to switch off V
3v3
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 V
3v3
are designed to work with a 3.3V
voltage rail, when the standby mode is used, V
GPIO_SPI
is requested to be at 3.3V.
3.3V
GPIO6
VGPIOS
p
i
Power Switch
1
VSu
pp
l
y
Int
V3v3
Regulator
-
+
StdByMode
3.3 V
1.9 V
0
1
External
connection