Forum: Analog Circuits TLV272 Rail to Rail problem DIODES

von mikel (Guest)

Attached files:

Rate this post
not useful

I need a expert tip for my problem by using a Operational Amplifiers 
TLV272IS-13 from DIODES. Rail to Rail, 3,3VCC to GND as power supply. In 
my circuit I use the TLV272IS-13 as a “Voltage Follower” to measure the 
net supply of 230V/50Hz over a rectifier bridge and a voltage divider. 
By reaching the max limit of net supply (300VAC) the Voltage Follower is 
by 3,3V. But unfortunately, the output signal of TLV272IS-13 is cut by a 
voltage of 2,92V.

I testes bigger capacities by power supply (22uF) between 3,3V and GND, 
but without positive result. I unsoldered all capacities in the circuit, 
unsoldered the pulldown, tested an pull up of 12k to 3,3V also I copied 
the circuit to an external board, but nothing helps the signal is cut by 

By using a simple 3,3V over an adjustable voltage divider I can go up to 
3,3V (3,25V) without problems, but if there is a frequency in the 
signal, the Rail to Rail does not work.
I changed to an operational amplifier type TLV272CDR from Texas 
instruments and it works perfectly. The 300VAC will be displayed as 3,3V 
after TLV272CDR.

Does I overlook something in the datasheet ?
Is TLV272IS-13 from Diodes not able do drive RtR ?


von jensig (Guest)

Rate this post
not useful
Phase reversal, if the resulting voltage after the voltage divider is > 

von Achim S. (Guest)

Rate this post
not useful
mikel wrote:
> Does I overlook something in the datasheet ?
> Is TLV272IS-13 from Diodes not able do drive RtR ?

The datasheet says "Rail to Rail output". But it does not claim a rail 
to rail input. If you use this OpAmp as a voltage follower, the input 
common mode range limits the usable voltage range.

The recommended Common Mode Input Voltage according to datasheet ends at 

You may divide the input voltage by a factor of 2 and configure the 
OpAmp as x2-amplifier - then the output should look better.

von Michael G. (Company: ATG) (spacemikel)

Rate this post
not useful

thanks for feedback.
That makes sense.


Entering an e-mail address is optional. If you want to receive reply notifications by e-mail, please log in.

Rules — please read before posting

  • Post long source code as attachment, not in the text
  • Posting advertisements is forbidden.

Formatting options

  • [c]C code[/c]
  • [code]code in other languages, ASCII drawings[/code]
  • [math]formula (LaTeX syntax)[/math]

Bild automatisch verkleinern, falls nötig