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

[scream_er]

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?

Thanks

 

[mvs sarma]

microchip have MCP6271 and MCP6281 please take datasheet from Microchip Technology Inc. is a Leading Provider of Micro controller and Analog Semiconductors, providing low-risk product development, lower total system cost and faster time to market for thousands of diverse customer applications worldwide. it is within.5$ in lot but one off might cost

 

[FvM]

A number of devices can be sorted out, because they aren't R/R: LM358, LM324, TLC272. LM358(=2/4 LM324) may however serve your application adding an output pull-up resistor to the circuit and can be hardly beaten when low price matters.

Form your list, TLV2771 has only output R/R capability, which may be sufficient for your application. It's supply voltage is also limited to 5.5V.

LM6144 and LT1466 have full I/O R/R, I would probably sort out the latter prise-wise.

Obviously, there much more R/R OPs available, either full (I/O) or O only rail-to-rail. They differ however in terms of supply voltage range, supply current, bandwidth, noise, offset performance, price. Not knowing your exact application, I can't suggest a particular device.

For standard requirements with I/O R/R in the 3 to 15V supply range, I'm e.g. using TLV2371. It's however not particularly low noise.

 

[scream_er]

@ FvM, i just need an op-amp that can amplify the voltage from a mic. So that it can be connected to micro-controller to get the best resolution. My controller is 0 - 5Vcc.

1) Rail to rail mean, +ve to -ve voltage right?
2) If I want Gnd to +Vcc, can it be rail to rail?
3) I want to use gnd and +Vcc using a single supply battery, so whats the best option?
4) 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.
5) 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.
6) I want an op-amp that can give me closest to +Vcc in this configuration.

Thanks

 

[FvM]

You have been previously asking for 9V supply, which would sort out some devices. For the microphone amplifier with 5V supply, e.g. TLV2771 would be good, also the microchip devices suggested by mvs sarma. But there are much more.

 

[scream_er]

I mean any op amp that can be operated within 5v to 9v using single supply is what I need. For TLV2771, I couldn't find the maximum output gain in datasheet.
1) Whats the maximum gain of TLV2771? (I need 200 gain either with single op amp or double op amp configuration.)
2) Also I want to use from Gnd to +5Vcc. Such that I can bias at 2.5V and achieve 5V. (Can TLV2771 do that.)

 

[FvM]

Most of your questions are asking for a better understanding of OP circuit basics and datasheet reading.

There isn't a thing like maximum output gain. In a rough estimation, you can calculate the achievable gain of a single stage as OP GBW/required signal bandwidth. An OP with 5 MHz GBW can achieve 25 kHz bandwidth with a gain of 200.

The bias point question has been already answered, I think. Yes, it's O.K. with this OP.

I mean any op amp that can be operated within 5v to 9v using single supply is what I need.

Neither a microprocessor nor TLV2771 will accept 9V supply voltage. Just refer to the datasheets. If you want a higher power supply than 5V for some reason, you need to choose a different type. It's been said before.

 

[scream_er]

The thing is I am using a Mic to pick up baby's voice. I'm not sure how much the bandwidth of the voice is. When I tried without amplification the voltage from mic is so small that the micro-controller cannot really convert well. So, all I know is the voltage from the mic with baby's voice (using oscilloscope) and that i need an amplification of 200 to achieve 5V to get the best resolution.

I found LM6142. In the datasheet for LM6142 it says Gain 108dB with RL = 10k (so, does that mean I can achieve 100x gain with one op-amp of these)?

The attachement named "output" shows how I want the output from op-amp to be (incase someone don't really get understand what i mean).

Thanks

 

[BradtheRad]

If 200 gain is adequate then you might get by with the LM386. Popular and inexpensive. You add a capacitor across two pins to boost the gain to 200.

It's easy to use because one input is internally biased to half the supply V. So no need to attach a 2-resistor voltage divider.

Its output would range from 0 to supply V. Since you're feeding output to an ADC, there will not be need for the output capacitor typically used to connect a speaker.

Normally it takes a line level signal rather than a mic level. It becomes a question as to whether your mic would drive it sufficiently. A typical 1mV mic signal would turn into 2V AC riding a V/2 DC component. This might not be sufficient.

Just to mention a simpler option... a high gain transistor would be able to do the job you are asking.