16 Channel Servo Driver ID 815

[RussellJames]

Hey Mike,

It's the small RPi robot guy -- I need advice on using the 16 Channel servo controller which requires a 5v @ 2A power supply with UBEC DC/DC Step-Down (Buck) Converter - 5V @ 3A output ID 1385 fed with 7.2v battery pack.

Does the servo driver limit the current surging through its circuits or would it try and draw the 3A available and go up in flames?

Please advise.

Thanks

[adafruit_support_rick]

The servo driver only draws as much power as it needs.

[RussellJames]

That response provokes me to ask the question in another way - if the are multiple servos and LEDs with a total current demand that is >2A the controller would try to draw more current than it is rated to manage?

I am just trying to make sure that a 2A controller matched with a 3A power supply does not create a situation similar to 18 gauge wire on a 15 amp fuse - where the wire opens (flames out) before the fuse blows.

Cheers

[adafruit_support_bill]

Yes. Multiple high-current servos exceeding 2A combined current draw can potentially overload the reverse-voltage protection circuit on the board.

[RussellJames]

Ok - that is helpful.

It appears that if I match these two devices I should place a 2A fuse between the output of the UBEC DC/DC step-down and the input controller to protect the controller. I believe the UBEC has thermo protection - so no worries there. That leaves ~ 900ma to powering up some robot add-on devices in the future.

Do you agree?

Cheers

[adafruit_support_rick]

Sounds good!

[JorgeRobles]

Hi:

I rather post on this thread as is related to the component and somewhat of the topic.
I don't have clear on my mind what is the maximum current output of the component, using a external power supply.
On my case, I want to drive 12 servos (Yes! a 3dof quadruped), but the minimum servo current is about 200ma or so, a full load of 2A (to 3A on move?)
I want to know if the driver could handle that. I guess "yes" as the video and info provided (issuing attach ~500mF capacitor) but I want to be sure not to burn the driver the big way.
I understand the external power rail is directly connected to the +V pins to the servo and the driver only signals its position, so the current is never drived by the IC, isn't it?

thanks in advance!

[adafruit_support_bill]

The limiting factor is the MOSFET used for reverse polarity protection on the external power supply. If you are extra-extra careful, you can bypass this by providing power to any of the V+ pins on the end headers or a spare servo header.