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JST connector current capacity
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JST connector current capacity

by featMikeTyson on Thu Oct 05, 2017 2:11 pm

I am looking to drive 2 meters of 144 LED Neopixel strip, and have designed the power circuit around the max theoretical current draw of 17.3A (safety first!)

Looking up the datasheet for the JST-SM connector, the current limit per pin is 3A, and is connected to AWG22 wire (~7A spec'd).

Assuming a linear power relationship (ha!), this would suggest I would be able to drive my strip at a maximum mixed-color duty cycle of around 17%. This is not an unreasonable operating point, but it also makes me wonder what the width of the power traces are (etc) and that makes me a little nervous, especially when considering the discharge of 1000uF cap recommended for voltage ramp-up, or in the event of a software bug overdriving the strip.

Can someone please advise?

featMikeTyson
 
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Re: JST connector current capacity

by adafruit_support_bill on Thu Oct 05, 2017 7:01 pm

With 2 meters of 144 pixel strip, you will probably want to feed power to at least two points (e.g. both ends) to minimize voltage drop. It is also a good practice to fuse each branch of the circuit to protect the wire in the event of a catastrophic short circuit.

The generally accepted ampacity for 22AWG in a 'chassis wiring' application is in the 7A range. a 7A in-line fuse on each power feed would be a safe way to go.

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Please be positive and constructive with your questions and comments.