OPA847: alternate part with Higher voltage range

There is no replacement with exactly the same properties.

The fastest 24 V opamp would be the THS4011 with a GBW of 0.29 GHz.

What electrical characteristics do you actually need?

So the OPA847 is a lower input noise decompensated VFA, in the 30V supply range, the similar part would be the THS4021

Hi All, Thanks for reply.

I will interested where propagation delay between input and output will be less than 5ns.

Basically I have input signal as 3.3V and output of op-amp needed as -5V. Any +VCC and -VCC can be available.

OPA847 is not reaching output -5V in the pspice simulation. any suggestions will be welcome on this.

Hello Ashutosh,

  The reason why OPA847 is not reaching +/-5V with power supplies at +/-5V is because the output voltage swing of the part is +/-3.5V. You would need a true rail-to-rail output amplifier at +/-5V. 

  You might be looking for a comparator which compares the signals at the input and depending on the reference voltage it saturates to either -VS or +VS. Here is a filtered list of our comparators with less than 5ns propagation delay. And here are two threads with discussion on this concept: thread1 and thread2. 

Thank you,
Sima 

Hi Sima, 

Could you please suggest part which support -5V output logic and 3.3V input logic.

Above comparator which is selected, none of them have this logic levels.

Thanks a lot

Hello Ashutosh,

  From my understanding, comparators can accept dual supplies. Looking at the linked parts, that might not be the case for some of the comparators. I am moving this thread to our comparator team for more inputs. They will get back to you on this thread shortly.

Thank you,

Sima 

Sima

Thanks for looping us in.

Ashutosh

Nice to meet you and thanks for your use of the forum.  We have a comparator family called the LM111 / LM211 / LM311 (different temp ranges) that have independent input and output power supply pins that meet your logic needs but are most likely too slow for your application if you need 5ns propagation delay. Our two comparator families that meet your 5ns propagation delay requirement are 5V max only (TLV3601/3 and TLV3501/2).

Just in case you are interested in the LM311 family, the input range could be powered with +/-12V and the output could swing +/-5V.  The only drawback is that the logic high +5V portion of the output logic is achieved with a pullup resistor.  This can cause the output rise and fall times to be slightly unsymmetrical depending the value of the pullup resistor value.

Chuck

Hi Sima, Thanks a lot

Hi Chunk, 

One general doubt by comparator can be achieve below requirement-

Input level 0V (Low level)  3.3V (High Level)

Output level -5V (low level) 0V (High Level)

Thanks

Ashutosh

TI has no comparator with these voltage ranges and the desires speed. (And logic voltage translators require a common ground.)

If at all possible, change the requirements so that input and output use the same ground.

Ashutosh

The input levels and output levels are possible with a comparator such as the LM111 but achieving the speed range that you requested is not possible with the LM111 family.  I have shown below how a 0 to 3V input could be translated into a -5V to 0V output using the LM111.

Chuck

Hi Chuck,

Thanks a lot for this circuit. We will redefine our requirement and check this circuit.

Thanks

Ashutosh

Ashutosh

Sounds great and thanks for following up.  I will keep your post open just in case you need to come back with any follow up questions.

Chuck