Hello everyone. I’m using a D24V150F6 in a robotics project to power some servos that are being controlled by an Adafruit Feather M0. I want the servos to only be powered when the robot has been commanded to move and remain unpowered otherwise (for safety and power saving).
I’m currently controlling the EN pin on the voltage regulator via a transistor, but every time the M0 resets, the servos are powered until the feather boots up to pull the EN pin low. Is there a way to setup the regulator so that it’s default behavior leaves the V_Out off?
I saw that the pullup resistor can be removed on the D24V22Fx and D24V50Fx regulators from this post:
I would just use those regulators, but I need the larger current output of the D24V150Fx. Can the D24V150Fx be modified to remove the pullup on the enable pin? If so, which resistor do I need remove?
The pull-up resistor on the enable pin of the D24V150F6 is internal to the regulator IC, so unfortunately, it is not something you could just remove from the carrier board like described in the post you linked to. However, you could still overpower it by adding an external pull-down to that pin. Something in the 100 kΩ range should be fine.
Thanks @BrandonM. I’ll give that a shot.
I’m using a transistor to control the pin with my 3.3v Feather M0 because I didn’t want the 5V from the EN pin sinking to the pin on the Feather. If I use an external pulldown like you said, does that mean I can forgo using a transistor since the EN pin shouldn’t want to go to 5V anymore? It makes sense to me but I just wanted a sanity check.
Yes, with the pull-down you shouldn’t have to worry about that.
By the way, even without the pull-down, the voltage on the EN is not simply 5V; it depends on your VIN voltage. That being said, you probably did not need to worry about that voltage since it is being pulled-up and not actively driven. Most modern microcontrollers have clamping diodes that would prevent damage in that case (although I am not familiar with the specifics of the Feather M0).