5v-3.3v unidirectional voltage adapter

217

04:23:12

MOSFET: BSS138, 2n7000 or similar.
You can find 6 of this in CD4050.

published 7 years ago

rich11292000

7 years ago

Pmos goes on high side, nmos on low side

eekee

7 years ago

Falls to 1.85V with a 1kR load. Swapping the FETs (as rich said) may help. In any case, it's not a voltage adapter, it has a full 3.3V power source. It only uses the 5V line to switch the 3.3V line. It could do that with just 1 P-channel FET.

eekee

7 years ago

Sorry, just 1 N-channel FET, with increased width. A P-channel FET would need an inverted input.

BillyT

7 years ago

Basically, the circuit is right as it is, just open the gate width.

eekee

7 years ago

The P-channel FET does discharge any capacitative load on switch-off.

LuxARTS

7 years ago

I didn't design this. This circuit it's inside CD4050.

LuxARTS

7 years ago

Also, I build it and works fine. Tested under 1MHz.

rich11292000

7 years ago

It's the fet width like billy said.

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