Switching regulator noise with micro-controller & IMU

Hi,

Is the output of Step-Up/Step-Down regulators generally stable enough to use as input power to micro-controllers (without any further linear regulator)?

Specifically, I’m thinking of using a Pololu Adjustable Step-Up/Step-Down Voltage Regulator S7V8A to power some 3.3V electronics including a Teensy 3.1 micro-controller and a MPU-9250 9-Axis IMU.

Would there be a general recommendation between:
[ol]
[li]Setting the regulator output at 3.3V and using directly (bypassing regulator in the micro-controller). [/li]
[li]Setting the regulator output at 3.7V and also using the linear regulator in the micro-controller to provide smoother power. (3.7V being the minimum it accepts). [/li][/ol]

As background, my circuit will likely have other power-line noise - the same battery will be powering a step-up regulator (to 8V) and running 2 Pololu micro-metal gear motors with PWM that are changing speed and direction - so I would like to take steps to reduce risk of noise affecting the micro-controller. (Will need to figure out what decoupling capacitors to use too).

Thanks,
Dan

Hi, Dan.

It should be fine to power your Teensy’s 3.3V input directly off of that regulator. For reference, that is the same regulator that we use for 5V power to the ATmega32U4 on the LV versions of our A-Star programmable controllers.

-Claire

Hi Claire,
Thanks very much. Would you recommend adding decoupling capacitors between the regulator and the Teensy, or does the regulator board already have sufficient? If so what size/s?
Regards,
Dan

The regulator already has some decoupling capacitors on both its input and output, so you probably won’t need any external ones, though adding more wouldn’t hurt. Also, depending on your power source, you might want to add an electrolytic capacitor to the input as mentioned on the product page.

-Claire

Thanks for advice…
Regards,
Dan