If I want to control a relay via the TX of a UART do I just connect the appropriate STM32 pin to the relay? Or is there anything else I need to do (besides programming)?

[DMill.16]

I'm looking to use a ITS4200S-ME-P relay to switch a high voltage signal and would like to control that via a UART. Per the datasheet this relay, "can be switched on and off with standard logic ground related logic signal at pin IN."

[KnarfB · Accepted solution]

It is not a mechanical relay, but a NMOS Power-MOSFET with on-chip protection and helper circuitry. It should work as described in the data sheet, and you are right about "can be switched on and off with standard logic ground related logic signal at pin IN."

The data sheet says "Operating voltage range: 11V < VS< 45V", which I wouldn't call " high voltage", but thats up to your application.

hth

KnarfB

[DMill.16]

Well..."high voltage" in comparison to 3.3V from the MCU...

Thank you for the complete answer. This gives me half my puzzle.

[Peter BENSCH]

ITS4200S-ME-P is not a relay, but a high-side switch, comparable e.g. to our high-side switch IPS160H. Theoretically, you could already connect it to an output of the STM32, but the ITS4200S needs a minimum input voltage of 3V to switch on, below 1.8V it is switched off, which is just about possible with a 3.3V supply, but no longer with a lower voltage of e.g. 2.5V. For comparison: our IPS160H switches above 2.2V = On, below 0.8V = Off.

But now the exciting question: do you really want to connect the high-side switch to the TX of a UART, or do you mean something else?

What should the high-side switch be used for?

Regards

/Peter

[DMill.16]

Well, since you ask...

I'm connecting to external devices that are powered and communicate via a "high voltage" (30VDC - 50VDC). Transmit is accomplished by pulsing the voltage at a lower level - say switching from 30V to 20V and back. So I have 20V through a diode pushing constant power out - and a relay that switches in the 30 V as needed (I keep the relay active for a normal state, and drop power to do a pulse). The circuit runs from 0 - 3Amps.

If there's a better way to accomplish this I'd love to know it.

[DMill.16]

I'm definitely going to keep the IPS160H in mind (and thank you for the suggestion). Right now it has one significant flaw - the usual suspects don't have it in stock. I see Mouser has a quantity on order...like most of everything else in the silicon world.