I got a "problem" and it is because of my lack of knowledge so I need your help.
First, the current design is like the attached below this paragraph. The power comes from a car battery (24v or 12v), then I power a DC-DC Converter
T1 and this the my
IC. So the converter
T1 has a pull up pin, internally,
EN that enables the converter.
What I want to achieve is when the car turns on, turning the key, the circuit powers up and when the cars shuts down, the circuit too. In my design I'm using a relay NO with the key contact and the battery on the coil and a GND on the common pin of the relay, on NO the
EN pin and NC not connected.
The key contact has 12 or 24v depending the battery.
The problem I got is the relay for 12 or 24V usually is a "Relay cube" that it is big (19mm x 15mm). I saw solid state relay for 3.3 or less voltage that are very small but for this I need another dc-dc converter just to drive this relay and this is more messy.
What will be an improvement for this circuit? A transistor?, but I don't know what kind because the specs for the voltage from base to emitter are low (base 24/12v to 0v) Or are there a some IC for this use case?
On a second iteration of the design I will have another event (key contact and IC pin) so I will need some logic gate for drive the
EN pin. Just to know if there is a better implementation.