Quantcast
Channel: Amplifiers forum - Recent Threads
Viewing all 18829 articles
Browse latest View live
↧

What does the input offset voltage mean

January 3, 2015, 3:49 am
$
0
0

Hi everybody,


sorry that I have to ask t his, but I just couldn't find any answer for this question. My problem with the value of the "Input offset voltage" in all the OPA datasheets is that I can't really believe these small values. In my case I want to amplify an audio signal which has a DC-offset of 2.5V so that the signal is positive at all times. Can I do that with an OPA like the OPA322 which has an input offset voltage of max. 2mV?
The OPA will be used as a non inverting impedance converter.


Thanks for your time.

Regards,

Lennart

↧
Search

OPA313 performance degradation at 1.6V Vs

January 5, 2015, 3:16 am
$
0
0

Hello Team,

I have query on OPA313 performance degradation at 1.6V supply.

Recommended supply is 1.8V to 5.5V as perdatasheet, however supply available in one of my customer design is only 1.65V & OPA313 suits their requirement due to low bias condition.

Kindly let me know, what information is available.

Regards,

Mahendra Patel

↧
↧

0-10V to 4-20mA interface, request industry standard suggestions

January 5, 2015, 1:35 pm
$
0
0

Hello everyone.

I have not been able to find any TI documents to help with this question. If there are some available, please advise, thanks.

I am requesting XTR110 industry standard suggestions for a 0-10V 4-20mA interface from an Eaton VFD analog output to an Allen Bradley PLC input using this chip. I had previously implemented it using discreet components but was dissatisfied with the linearity and thermal stability. Although the XTR110 replaces almost all of the circuitry I had designed, I am concerned with industry standard implementation and protection of the device in student workstations.

I am including the basic circuit with the following questions:

Recommended parts for through hole implementation:

Clamp diode to protect A1 from -.5V at pin 4

A suitable external mosfet that is not in a to-92 package (I can not find this from available recommended parts)

A suggestion for protection of the external mosfet drain which is wired directly to the PLC analog input card

Please take a look at my simple implementation and make suggestions.

Thank you very much.

↧

Inquiry regarding settling time (ts) on LMV932-N

January 6, 2015, 1:49 am
$
0
0

Hello, all

Now we have one inquiry regarding settling time (ts) on LMV932-N from our customer.

Please refer to the item below, and feedback us with your comment.

When referring "11.3.16 Settling Time" on "Chapter 11 Understanding Op Amp Parameters" (SLOA083) page 11-22, there seems to be defined as "Settling Time" for each OpAmps.

However, we could not this information on the datasheet of LMV932-N (SNOS993N).

Please let us clarify whether we could get this information, in order to define proper signal input delay time after powering on this device.

We thank you in advance for your information. 

Best regards, 

↧

INA2128 or INA2134?

January 6, 2015, 3:51 am
$
0
0

Hello, I have a need to bring a signal into my circuit whilst preserving its fidelity as best as possible. It isn't audio, but it has the same sort of requirements as the very best audio might require, so an answer assuming an audio line input would be very useful; ie best noise and THD performance. If I don't have onerous common mode requirements, such as common mode outside the limits in the data sheet, is there really any reason not to use the instrumentation amplifier (INA2128) in preference to the audio differential receiver (INA2134)? Both datasheets refer to somewhat unrealistic source impedances of 0 for some of the test conditions, so it makes comparison tricky. Taking, as an example, the output noise voltage at 1kHz, the audio device quotes 52nV(sqrt(Hz)), whereas the instrumentation device for the same parameter quotes 8nV(sqrt(Hz)). Why would an audio engineer ever choose the audio device in place of the instrumentation amplifier with open gain resistor, especially if he was unsure of the source impedance of the input signal? Thanks for your time. Steve

↧
↧

Can I use AFE with photodiode?

January 6, 2015, 4:27 am
$
0
0

Hello,

I found LMP91050 when I looking for the amplifier for photodiode.

I don't know about the LMP91050 details.

Who can tell me whether can I use this IC with photodiode?

Thanks in advance,

Cheol Lim

↧

What is the max output current of the OPA1664 with a +-12v supply

January 6, 2015, 10:18 am
$
0
0

I'm trying to determine the max output current of the OPA1664 with a +-12v supply. The data sheet refers you to the typical characteristics graph. Operating conditions are VS+-15V, Rl=2k unless otherwise noted, but the output voltage vs. output current graph on page 12 shows output voltages of -+18v up to over 30ma.

↧

TLV2211

January 6, 2015, 10:30 am
$
0
0

Does anybody know how much input capacitance these can handle when used as a I/V converter with a 100G Ohm feedback resistor?

Does the input capacitance influence the open loop gain?

↧
Search

Breakdown of LMP8277

January 5, 2015, 11:30 pm
$
0
0

Dear, All

The breakdown by which output of LMP8277 becomes fixed 2.5 V by customer's system occurred.
Power voltage is 5V.
The customer would like to know whether it'll be 2.5V output fixing because of a breakdown of LMP8277.
Then, there are 2 questions.
- Does the circuit which makes 2.5V inside LMP8277 exist?
- If there is a block diagram more detailed than 'Figure 20.' in the data seat, is it possible to show it to the customer?

Thanks, Masami M.

↧
↧

OPA512 issue

January 7, 2015, 2:06 am
$
0
0

Dear Sirs

My customer uses OPA512 for driving huge current .

The circuit is shown as below.

The load of the OPA512 is resistance (0.5Ω).

The gain of OPA512 is 5.02.

The input voltage of OPA512 is almost 0.009V.(The output voltage of OP512 is 0.04518V, driving current is about 90mA)

And OPA512 will be unstable. (There is a Vpp 1.5V wave on the output of OPA512 )

Could you help me about the question.

Thanks~

↧

Powerline communication for irrigation system.

January 7, 2015, 5:33 am
$
0
0

Hello everyone!

I have a system which use a RS485 interface to communicate with other subsystems, it is an irrigation system. I am thinking to change the interface from RS485 to powerline communication over 24VAC, all the system use a 24VAC power supply because all the solenoids need 24VAC to open/close. What is your opinion? Would I find interference problems from solenoid? It would be easy to implement? expensive?

Thanks you!

Luis

↧

REF problem of INA155UA

January 7, 2015, 5:54 pm
$
0
0

My input voltage range is from 0 to 200mV. The signal power supply is 5V. In order to avoid the rail-to rail effect, I will a REF3112 to generate 1.25V reference to the REF Pin of INA155, In theory, the output voltage is G(V+ - V-)+REF. But I have found that the output is 0 when the input is zero, the voltage amplify is 10 but not very linear when the input voltage changes. My question is why the output is not Vref when the input voltage is zero. I have tried to connect the REF pin to GND. The output is zero, but I could understand that. But why I connect the REF to the voltage reference, the minimum output is not VREF, but zero. Thanks!

↧

PGA309+tps70950 under electrically fast transient test

January 7, 2015, 7:42 pm
$
0
0

Hello

    according to your reply for my question of "PGA309+tps7A41 under electrically fast transient test" last December, our experiment is ok.

   but PGA309+tps70950 is still in failure, I think that tps70950 is more weak than TPS7A41.

   could you give me some advices?

Thank you.

 

best regards.

Weiming

↧
↧

Radiated susceptibility issue of OPA547F and OPA4228UA

January 7, 2015, 11:48 pm
$
0
0

We use the OPA547F and OPA4228UA in Audio circuit,But the circuit is very susceptible to Radiated susceptibility (200V/m) test.

How to deal with this issue?

↧

ADS1258 Use of MUXOUT and ACDIN

January 8, 2015, 11:38 am
$
0
0

Hello,

I want to use an ADS1258 for bridge measurement evalution, similar to the one in the datasheet on page 45. However, I'm not completly sure about the use of MUXOUTN/MUXOUTP and ACDINN/ACDINP. Is the assignment of these pins necessary?

↧
Search

0 - 2.5V to 4-20mA Transmitter

January 8, 2015, 11:39 am
$
0
0
Dear Mr. Collin Wells
I'm a new member here and I hope you can help me :)
I would like to transform input voltage 0 - 2,5V to 4 to 20mA. I tried to change Rset to 1,5k but it's not ok.
Results when Rset = 1,5k:
Uin = 2,5V -> Iout = 20mA
Uin = 1,25V -> Iout = 13,33mA
Uin = 0V -> Iout = 6,67mA

Can you give me some advice which elements on the schema above do I have to change (new values)?

Thank you!
Best regards
Joc
↧

Bias Currenet

January 9, 2015, 12:27 pm
$
0
0

In the OPA2107 the datasheet shows the bias current increasing with temperature. When I measure the bias current, I don't see this even up to 125c. It remains fairly flat. I understand that with protection diodes one might see leakage current increase with temperature, however, if there are two such diodes (one to V- and one to V+), they would cancel out and only the gate current remains. With the internal gate biased at around 0V and common mode at 0v, I would expect the bias current to not change that much over temperature. Does anyone out there have experience with this OPA2107? Thank you.

↧
↧

need some information on transimpedance amplifier

January 12, 2015, 1:54 am
$
0
0

Dear all


The attachment is the design of a photodiode preamplifier.

i used a capacitor to block the DC current from going through the opamp  and i connect a positive voltage bias on the cathode.

i used high gain at first stage of amplifier 


Can I design in this way?

because the application circuit in lmv794 does not have a AC coupling capacitor.


 Thanks in advance.

(Please visit the site to view this file)

pls tell the circuit design is correct or wrong and suggestion of using capacitor series with photodiode 

↧

Inquiry regarding LARGE-SIGNAL STEP RESPONSE on OPA2188

January 12, 2015, 6:45 am
$
0
0
Hello, all
Now we have one inquiry regarding LARGE-SIGNAL STEP RESPONSE on OPA2188 from our customer.
Please refer to the item below, and feedback us with your comment.
When referring Figure 31. on datasheet page 13, we could understand that this device has some undershoot when the input signal significantly dropped.
Please let us know how this phenomenon could be reduced.

For your reference, we are considering about the case that the input signal is from DAC7554 as dropping 5V to 0V with applying 15V into V+ and -15V into V-pin of OPA2188. (Actually, the input signal range is supposed from 0 to 5V). The undershoot was observed on our environment which seems to be caused by the reason above. 

We thank you in advance for your information.
Best regards, 
↧

LM339 - Vicr, Vi range

January 14, 2015, 5:43 am
$
0
0

Hi all,

Would you mind if we ask LM339?

<Q1>
About Vicr, the datasheet shows that Vicr range are "25°C 0 to Vcc–1.5", "Full range 0 to Vcc-2.0".
So, IN+ and IN-(both) must satisfy this range, mustn't they?

<Q2>
Input voltage range (either input), VI is -0.3 to36V.
That's why, if no suply to Vcc and VI suply voltage the range -0.3 to36V,
VI isn't broken, right?

Kind regards,

Hirotaka Matsumoto

↧
Viewing all 18829 articles
Browse latest View live
Search
<script src="https://jsc.adskeeper.com/r/s/rssing.com.1596347.js" async> </script>