Hi Everyone,
I was wondering if anyone could help me with a small problem I've been having.
I'm trying to use a ULN2003 darlington array IC to individually control a series of relays.
I am using the 4.2v signal voltage from my microcontroller to switch the transistors and a regulated 3.3V supply for the IC and relay.
Unfortunately when I try to turn the relay on using the microcontroller, all of the darlington pairs on the IC turn on and all my relays turn on as a consequence.
If I remove the 3v3 regulator and power everything from Vbatt, the problem goes away however I would prefer to power the IC and relays from the regulator for power saving reasons as I can turn it off when not required.
Does anyone know why my initial setup does work?
Thanks!!
I was wondering if anyone could help me with a small problem I've been having.
I'm trying to use a ULN2003 darlington array IC to individually control a series of relays.
I am using the 4.2v signal voltage from my microcontroller to switch the transistors and a regulated 3.3V supply for the IC and relay.
Unfortunately when I try to turn the relay on using the microcontroller, all of the darlington pairs on the IC turn on and all my relays turn on as a consequence.
If I remove the 3v3 regulator and power everything from Vbatt, the problem goes away however I would prefer to power the IC and relays from the regulator for power saving reasons as I can turn it off when not required.
Does anyone know why my initial setup does work?
Thanks!!