Our Technical Support team will be out of the office on Wednesday, April 23 starting at 12pm. Tech Support will reopen with normal hours on Thursday, April 24 at 9am. Thank you

Member #58693

Member Since: January 22, 2009

Country: United States

  • Product COM-00784 | about 10 months ago

    I bought a couple of these to put between an arduino and some 12V automotive relays. Unfortunately they only are rated for up to 50mA/ch and the coil current of my relay is 75mA so I bought some of the next step up in the series the PS2502-4’s from digikey that can handle 160mA/ch.

    I’m worried about the power dissipation that is 120mW/ch on both devices. The relay is going to draw 900mW (75mA * 12V) but to calculate the power dissipation of this device I just need to take Vce(sat) which is .3V on the PS2501-4 and 1V on the PS2402-4 and multiply it by Ic of 75mA right? So with the PS2402-4 I would have 75mA * 1V = 75mW and be well within the 120mW / channel rating right?

    Is my reasoning here right? Is Ic just the current through the relay like I assumed? Is there any Vbe that I need to worry about (Not sure what this would be with a photo transistor).

    Is it ok to drive the relay directly with the opto-isolator or should I just use it for protection and use it to turn on something like a TIP120 instead?

No public wish lists :(