Tool/software:
Hi Team,
As title, we want to use LM2904LV-Q1 as voltage follower architecture. From my understanding, Vout = Vin when Vin < V+
Our V+ is 3.3V and V- is GND. My purpose is that Vout = Vin when V+<3.3V and when Vin>3.3V(no larger than 5V), the Vout = 3.3V.
Can LM2904LV-Q1 fulfill our requirement? If not, can you propose a 2ch OPA solution for me?
Regards,
Roy
Hey Roy,
Yes, the LM2904LV-Q1 will not phase invert like the LM2904-Q1 would, per figure 6-21 in the datasheet. Please make sure that if the input voltage exceeds VCC, current into the pin is limited to <10mA.
Best,
Jerry
Hi Jerry,
Thanks for confirmation. Previously, we used LM2904BA-Q1, but met the issue.
As below circuit, our VDD is 3.3V and V+ is 5V. I expected that the pin1 is 3.3V because the Vout would be clamped at 3.3V. But Vout here was only 2V.
Do you have any comment for the phenomenon?
Regards,
Roy
Hi Ron,
Thank you for your suggestion. I search the single power/dual power/rail-rail OPA in google.
May you help let me know if my understanding is correct or not?
For LM2904-Q1, the max Vout is (V+)-2V and min Vout is (V-)
For TLV9002-Q1, the max Vout is (V+)+0.5V and min Vout is (V-)-0.5V.
Do we have more accurate rail to rail OPA? Maybe +/-0.1V for Vout(max) and Vout(min)
To limit current, if our V+(max) = 5V, R181 that we selected should be 5V/10mA = 500ohm(above the value).
Is it correct?
Regards,
Roy
