The question of DC solid state relay

[Alanlin]

I use a small solid state DC controlled DC normally open solid state relay with 4 pins: IN+ IN- OUT+ OUT-.
The connection method of the S3C2440 selected by the main control chip is as follows:
OUT+, OUT- are used as switches to control the charge and discharge of the capacitor;
IN+ connects to 5V power supply; IN- connects to 2440 GPIO through a 470 ohm current limiting resistor;
The problem now is: as long as the circuit board power is turned on, the relay is in the closed state and is not controlled by the 2440.
Relay parameters: control voltage 3-14V Control current 6-15mA

 

[barry]

The relay s damaged.

 

[d123]

Hi,

Relay part number? Schematic of circuit section described? Is 2440 GPIO high-Z or sinking and does it have an internal pull-down, etc?

 

[FvM]

You verified that the GPIO pin driving the SSR is high in intended off state?

 

[KlausST]

Hi,

I agree with d123.

If you suspect there is something with the relay... the first things you should provide is
* relay part number
* schematic
* microcontroller code that shows the port setup and ON/OFF of the relay.

The first thing to debug the problem should be to use a DVM and measure
* the relay output voltage in ON and OFF state
* the relay input voltage in ON and OFF state
...and report them here

What worries me: The microcontroller seems to be a 3.3V device .... but you talk about 5V ....
--> schematic needed

Klaus