TVS Diode Selection?

General discussion of the MCP motion controller product line
JorgeP
Posts: 12
Joined: Thu Nov 16, 2017 8:16 am

TVS Diode Selection?

Postby JorgeP » Wed Apr 04, 2018 6:05 pm

Hello again,

I am having some difficulty figuring out an appropriate TVS Diode that will be appropriate for my intentions. I did a google search and found some notes by MicroSemi (PDF) on this process. To be honest, I have no idea how to perform all these calculations. I just want to get my project going safely.

My system is 24V and is using the MCP263 motor controller with 1000 Watt max peak current motors that nominally operate at 250 Watts 22V. I am trying to build the protection circuit shown in the Data Sheet on page 8.

Here is a list of components I have to complete the circuit


I am stumped on D1, is there a general part I can order that should be safe enough for general use with the motor controller? I posted a comment with the general rundown of my project with an attachement of a rough schematic of my design and links to most components I will be using at this link.

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Basicmicro Support
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Joined: Thu Feb 26, 2015 9:45 pm

Re: TVS Diode Selection?

Postby Basicmicro Support » Thu Apr 05, 2018 10:27 am

The MCP263 already has TVS diode built in so you dont need to add anymore.

For those that want to know though, the TVS should be selected to clamp at the highest voltage the system can survive. TVS diodes will only protect against spikes, not continuous over voltage though the larger the wattage rating of the TVS the longer they will survive an extended overvoltage.

In your case the 260s already have them installed. You just need to get a properly sized fuse. You need to look at the fuse timing table that shows how quickly it will open at a given current. You want it to open quickly in a dead short situation(.1 to 1 seconds at slightly less than the batteries maximum current capability). But you dont want it to open under normal operations.

JorgeP
Posts: 12
Joined: Thu Nov 16, 2017 8:16 am

Re: TVS Diode Selection?

Postby JorgeP » Thu Apr 05, 2018 9:22 pm

IMC Support wrote:The MCP263 already has TVS diode built in so you dont need to add anymore.



Thank you for clarifying. The data sheet doesn't state that unless I missed it.

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Basicmicro Support
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Joined: Thu Feb 26, 2015 9:45 pm

Re: TVS Diode Selection?

Postby Basicmicro Support » Mon Apr 09, 2018 10:07 am

No, I dont beleive it does. All our models larger than or equal to the Roboclaw 2x60 have TVS diodes. All small models(MCP230,ROboclaw 2x45 and under) do not.


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