How do I search for multi-output relay/driver chip for negative voltages?

Question

I have a strip of RGB LEDs. If I attach a multimeter between the common pins and another pin like the red power, I measure -2.4V . I think this is what is described as common anode.

I have an L293D motor driver relay chip, but its 4 outputs must be positive voltage, so I would have to connect the LED's common pin to the driver output, and all the LED power pins to the ground. This prevents me from controlling red, green, and blue independently.

I would like to find a relay/driver chip that supports multiple independent outputs and supports negative voltage. I also want to be able to use pulse width modulation (PWM) to control brightness. I am pretty sure it would be a bad idea to wire this directly to the pins of a microcontroller since it seems to draw 200 mA when I measured the red wire.

Something like the DS3680 supports negative voltage, but the schematic on the datasheet seems a bit complicated, and I do not have enough training to guess why.

If I search in Relays>Solid State Relays at digikey, the Voltage-Input criteria only lists positive numbers. How would I search for a relay that supports negative voltages, and allows the supply voltage (-2.4V) to be smaller than the logic voltage (3.3V)?

Answer 1

You don't need support for negative voltages. If you attach the positive lead to common anode, and negative lead to LED pin, you'll read +2.4V.

You do like any other LED driver, you give a positive common, and pull current via each LED down to ground.

You can do that with three of the L293D channels and leave the fourth unused.