RFC: osmo-clk-gen v2

Sylvain Munaut 246tnt at gmail.com
Fri May 24 10:39:33 UTC 2019


> I again took a buffer (voltage follower) formed of a generic R2R-IO,
> unity gain-stable CMOS opamp (MIC7300, TLV9001...). Those supply (or
> sink) 40 mA and more. But the max. output current depends on the output
> voltage, so, if we want to continue with that approach, I'd likely add a
> BJT current helper stage behind the opamp (BJT collector on 5V). We have
> almost no dynamic demands on that opamp, so disregarding any phase
> errors we introduce by driving large capacitive and resistive loads, it
> would work w/o a BJT, but let's see...

Heh, I just prototyped something last weekend for another project with
controlled VIO using a mcp6001 and a N-mos pass transistor. ( It sure
doesn't have the lower drop-out configuration but I think it's more
stable that way ).

> So I don't see an external ref voltage input on that PCB... maybe your
> use case would explain your needs here! ;)

I don't see the need for a external vref input.
VDDANA is fine.



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