USB6501 Digital output to trigger 5vdc relay

[solehinrobian]

Hi All,

I am using USB6501 to trigger a 5vdc relay 

when i pull high, i not see the relay triggered. 

after troubleshoot i found that my USB6501 at port P0.0 only give 3.3 v instead of 5v.

are they any setting that i need to do to increase the voltage from 3.3v to 5v?

thanks in advance

[Antoniooh · Accepted solution]

This device has two digital output modes, "Active Drive" and "Open Collector", in order to get 5V you should be using Open Collector mode, but it's driving capabilities are limited, i suggest you to use a circuit between the USB device and the relay.

Page 2 of the spec for this device.

Saludos.

[crossrulz · Accepted solution]

With the Open Collector, you have to supply your own 5V source.

Looking at the specification, it looks like the active output works in the 3.3V range.  This will still work for TTL devices, but not likely for an actual relay.  You are also likely limited by the current required to turn on your relay.  You should at a circuit to boost that current and voltage level up.

[santo_13 · Accepted solution]

Though this snippet is from the 6509 user manual, the concept is still the same for 6501 too.

As crossrulz described, you need an external transistor or buffer that can switch the voltage and current required by your relay coil.

Typically, 5V relays require a coil current of 20mA which the 6501 cannot supply.

[solehinrobian]

Thank you everyone for the respond.

i've add ttl in between usb device and relay. and it works

actually i get a relay module that already sort the ttl and relay. only need to add external power supply and now can trigger the relay