Required to use a DB9 connector to pass DC to unit requiring 12V/5A supply. An easy way to do that is using a DB-9 to Terminal Block adapter. But most DB-9 to TB adapters I see have 3 A or less current rating per pin. How can use such adapter to make it pass a 12V/5A stably?
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Is it only being used for power and nothing else? – Passerby May 19 '21 at 01:12
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There are some DB9 connectors with 5A rated pins. Most are 3A rated pins (or higher) Assuming you design for the lower standard your options are use a higher voltage and use a switching regulator to bring it down to the Voltage/Amperage needed, or... use multiple pins. For 5A on a 3A contact, you'll need 4 pins, 2 V+ and 2 Gnd. Just ensure everything in the path can handle the current.
Passerby
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Interesting, when you say 4 pins, how can I convert my 2 wire DC power cable to map to 2 V+ and 2 GND? – eecs May 19 '21 at 01:20
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You would have to connect the 2 wire cable to 2 sets of pins. Run 2 cables from the supply or splice a second cable to each conductor. Or use the terminal block adapter you mentioned. You just need to ensure whatever method you choose can carry the current in question, the right gauge wires, pcb traces etc. – Passerby May 19 '21 at 01:30
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Seeing that 5A is already relatively high a current to pass it trough a d-sub pin, I'd recommend at least not putting a large terminal block at the connector. Instead, I'd get a connector with solder lugs, and solder in appropriately sized cabling. That inherently solves the issue.
No matter what you do, you won't be able to use a terminal block adapter when that's not rated for the current you need.
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Thanks. Agree, soldering is definitely an option, but was looking for a quicker solution. – eecs May 19 '21 at 01:19