Latching relay driver

[baba_sanfur]

Hi All,
I need help in designing a latching relay driver. The relay is single coil and need 5v @ 200ma. The problem is that my MCU uses 3.3v GPIO.
The system must be extremely low cost, and consume as little power as possible.
I implement it by 4 MOSFET (2xN-ch, 2xP-ch) as an H bridge. The problem is with the voltage levels: to change one set of FETs (P + N) I need 5v or 0v – which I don’t have (MCU GPIO=3.3v). I tried to add 2xnpn transistor to drive the MOSFETs (ugly solution) and it didn’t work at all.
I added the circuit that I used; can anyone help my in designing this driver? Or have other solution to my problem (remember – low cost and power).

Thanks,
Nir

 

[crutschow]

You need some sort of switching converter to generate the 5V from the 3.3V which tends to be complex, for example https://www.electro-tech-online.com/custompdfs/2009/02/AN2025.pdf. If you really want low cost and power then use a 3.3V relay.

 

[blueroomelectronics]

Much easier to use a dual coil latching relay or a 3V latching relay.