STMicroelectronics FlexSPIN: SPI configurable stepper and DC multi motor driver evaluation board EVAL6460 EVAL6460 Data Sheet

Doc ID 17713 Rev 1

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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.

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.

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 

VGPIOSpi 

Po

wer Switch

 1 

 

VSupplyInt 

V3v3 

Regulator 

- 

+ 

StdByMode 

3.3 V 

1.9 V 

0 

1 

External 
connection