I'm using a THS4521-HT with a single 3.3V supply. I'm happy with an output common mode of 1.65V, is there any advantage of driving the Vocm pin with a buffered 1.65v signal rather than simply leaving it unconnected?
Kind Regards
Martin
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I'm using a THS4521-HT with a single 3.3V supply. I'm happy with an output common mode of 1.65V, is there any advantage of driving the Vocm pin with a buffered 1.65v signal rather than simply leaving it unconnected?
Kind Regards
Martin
The internal default Vocm is just a large R divider from the supply, so any supply variation will feed right into it. Also, at minimum put a cap to ground on that pin to reduce the noise on that pin - that term can get into the output differential noise via R mismatch in the signal path R's
Hi Martin,
Good recommendation from Michael here, posting the relevant section of the datasheet for you as well. (Application info on pages 18-19)
Best,
Sam
Thanks, I've added the capacitor. From what I can tell there's no advantage to actively driving this signal if I'm happy with the half supply rail cm
You are correct Martin, for a lot of apps just letting it default to mid supply with an external cap is adequate - which is why the standard FDA definition includes that midsupply default.