Regarding 3.3V Sensor Power Supply Option

[sakibnaz]

Hi all.

I have a ques ... regarding the best professional way to control Power (ON/OFF) of some Sensor (Light, Microphone and IMU) which I like to drive by 3.3V.

My system is Li-Po 3.7V Power and it have Boost 5V for CPU and 3.3 LDO for MCU supply.

Now I like to have this three Sensor but I want to have full Power ON/OFF Control where when in Sensor OFF Mode I want the related Power Control Circuit for the Sensors will consume as minimum possible Power (almost zero amp).

FYI please see the attached for my system Block diagram.

Now what will be the best way to apply Power to the Sensor? I planned use extra three small LDO's (Input 5V and Out 3.3V) and supply to each Sensor where LDO's 3xEnable Pin I can connect with 3xGPIO to control. But not sure if its good idea.

Please advise.

Thanks.

 

[KlausST]

Hi,

You want low power but you give not a single word about the supply current and voltages of your sensors.
Nor how long the sensors should be powered and how long they will be OFF.
Also not whether the sensors are ON/OFF the same time or independently.
How the sensors are interfaced ....

Klaus

 

[sakibnaz]

Hi Klaus.

All this three Sensors will not take much Power. If I can design to provide 50mA - 100mA max supply current fro each Sensor will be enough.

The Sensors will be rarely active. Most of the time Sensors will be OFF.

And yes, we need to ON/OFF Sensor independently.

Light and IMU Sensor are I2C based and Microphone is Analog.

Regards.

 

[FvM]

Switching power supply is probably adequate for analog sensors. If the current consumption is low, they may me simply supplied by a GPIO pin. Digital sensors have often programmable power down mode and can be supplied permanently. It should be also checked, if I2C pins can swing above VDD, otherwise you would need separate I2C bus.