Need suggestion on single supply rail to rail op-amp?

Discussion in 'General Electronics Chat' started by yaantey, Jan 7, 2012.

  1. yaantey

    Thread Starter Active Member

    Oct 7, 2011
    Can someone tell me a rail to rail op-amp that can be used with single supply 5V to 9V. Something easy and similar to LM358, also inexpensive.

    I want a rail to rail op-amp that use single supply so that I can bais it somewhere at 2.5V and still get 0 to 5V using a battery. I have found a couple of op-amps, which are: TLC272, LT1466, LM324N, TLV2771, LM6144. What could be the best choice, or is there anything else that you suggest?

  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    You are confusing , did you know that ?

    What is actually meant by Rail to Rail ?
  3. yaantey

    Thread Starter Active Member

    Oct 7, 2011
    rail to rail mean -ve to +ve voltage right?

    1) Basically I want the output of a mic to be amplified so that I can connect it to micro controller ADC, which has 0 to 5v.
    2) I want a single supply so that I can use gnd and +ve and bias in the positive region. So that the minimum would be 0V and maximum would be +Vcc.
    3) I want an op-amp that can give me closest to +Vcc in this configuration.
    4) I need the op-amp to have a gain of 200 when either in single mode or dual mode.

    Last edited: Jan 7, 2012
  4. MrChips


    Oct 2, 2009
    LM6142 (dual) and LM6144 (quad) are rail-to-rail, single supply, wide voltage range, low power, high bandwidth.
  5. yaantey

    Thread Starter Active Member

    Oct 7, 2011
    With LM6142 can I produce an output as shown in the attachment "Output".

    1) The datasheet for LM6142 says Gain 108dB with RL = 10k (so, does that mean I can achieve 100x gain with one op-amp of these)?
    Last edited: Jan 7, 2012
  6. Markd77

    Senior Member

    Sep 7, 2009
  7. Audioguru


    Dec 20, 2007
    Why do you think that a lousy old LM324 is better than a lousy old LM358? They both use exactly the same lousy old opamps!

    Most opamps have an open-loop gain of almost one million. Negative feedback is used to reduce the gain to a useable amount (100 if you want). The datasheet will show the maximum output voltage at high frequencies depending on the amount of gain.
    xox and Sparky49 like this.
  8. CraigHB


    Aug 12, 2011
    I used the Microchip MCP6001 recently for a current sensing circuit. It works nicely and I'm impressed with the low offset and max voltage swing. It's one of the most inexpensive op amps as well. Though absolute maximum Vdd is 7.0V. Don't know if that would preclude it for you or not.

    As already mentioned, open loop gain is usually around 100dB for any op amp. You normally set the gain with a feedback circuit. I'm using the MCP6001 with a 30dB gain to amplify the drop across a 10mΩ current sense resistor. The signal is read by a PIC ADC. The output is very clean and I'm really happy with that part.

    Last edited: Jan 9, 2012