2023-12-18 07:48 PM
I'm looking at this ST Micro part
ST MICROELECTRONICS TSX339IQ4 --- power from 2.7V to 16V.
But Vicm limitation of Vcc - 2V. At 3.3V-2V = 1.3V.
But need Vcm at 2.5V., so 2.5V + 2V = 4.5V, so likely Vcc = 5V.
as an alternative source to this TI part:
TEXAS INSTRUMENTS LM339LVRTE -- power from 1.65V to 5.5V. Vcm from 0 to Vcc.
I'd like to power the IC off of 3.3V and don't have a convenient source of 5V. And I *must* use a Vref of 2.5V given the other I/O requirements.
Unfortunately although the TI part will work at 3.3V with Vref of 2.5V (since its allows Vcm is 0-Vcc), the ST Micro part won't work that way. It's Vcm is limited to Vcc - 2V = 3.3V-2V = 1.3V, 1.2V *below* the required Vref of 2.5V. To allow the ST Micro part to work at 2.5V, it would require a Vcc of 2.5V+2V = 4.5V => 5V. Both the ST Micro & TI would be OK at Vcc=5V *but* I don't have a source of 5V on this design or way to distribute it to the *many* comparators used.
Any suggestions, or alternate parts that are footprint equivalent for ST Micro vs. TI vs. ???
2023-12-19 02:36 AM
Welcome @RescueBlues, to the community!
If you are working with 3.3V and need low current consumption you could use the TS884 instead.
Hope it helps?
Good luck!
/Peter
2023-12-19 09:41 PM
Thanks, good idea.
I was comparing the ST Micro TS884IQ4T to the TEXAS INSTRUMENTS LM339LVRTE. Similar specs, rail-to-rail Vicm, same QFN16 package.
SOOOO Close, but... I then noticed that the pinouts for the two are different (e.g. TI part has all their OUTs 1-4 on one side, but the ST Micro mixed INs & OUTs on two sides. Then a few diffs for VCC, GND, etc.). Too bad. I'd have to pick one xor the other and can't put the two on the same AML.
2023-12-20 03:54 AM
If you can't or don't want to use the TS884IQ4T, I'm sorry and you have to use the other device, because STMicroelectronics has no alternative with this pin assignment in a QFN16.
Good luck!
/Peter