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LMC6484: looking for single channel alternative part.

August 23, 2018, 12:37 am
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Part Number:LMC6484

Hello,

I'm using LMC6484 to convert a LM35 temperature signal (about 0 - 70° C) into a 0-5 V range which is then fed into an ADS1100. 

I chose the LMC6484 as it was used in a similar existing design ;-)  Now I'm looking for a replacement as I'm only using a single op amp of the LMC6484. It is operated as a single-supply (5V) non-inverting operational amplifier. See attached circuit.

What would be a good replacement, e.g. would a LMC6061 or OPA317 work as a "drop in" replacement? In terms of voltage offset and drift they match or surpass the LMC6484 and I think their lower GBW is of no relevance.

Thanks!

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TIM Green's OP AMP Stability Analysis 4 PPT files

August 23, 2018, 4:02 am
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TINA/Spice/LMP2012QML-SP: Input common mode range when powered by 3.3V and Pspice model.

August 23, 2018, 7:41 am
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Part Number:LMP2012QML-SP

Tool/software:TINA-TI or Spice Models

I does not seem the LMP2011 Pspice model is valid as simulation does not agree with datasheet. 

The datasheet specs gain and phase margins at 2.7V with Vcm=1.35V.  However opamp model fails to simulate properly at this bias voltage see below. (output is not same as input in voltage follower unity gain config and if I evaluate gain and phase margins at this bias I get garbage with gain down to -160dB at 1Hz )

If previous advice that device cannot be operated above Vcm=VDD-1.8V then how can datasheet specify phase and again margins there.

We also have tested devices at 3.3V supply at Vcm=1.65V that operate properly but simulation model also fails there.  

If Vcm is made lower (<<VDD/2) the simulation model works but phase margin is somehwhat worse than spec. More like 8.8dB,42deg. 

Do you have a better Pspice model that agrees better with datasheet and actual parts?

Mike

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Tell me more about the ISO224!

August 23, 2018, 12:16 pm
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Part Number:ISO124

Hi,

I am also interested in the smaller IC that is going to be released this year. I am using the ISO124 and that would be great if I can find another IC that is smaller and does the same job. Can you please send me the info for that part as well? 

Thanks  

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Problems with ISO124

August 23, 2018, 5:48 pm
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Hi,

I am using the ISO124UE4 Precision Isolation Amplifier. I have designed and fabricated a board that get the data from sensors and send it to a processor. In order to isolate the input data lines and the processor I have used the ISO124. My problem is that they are getting hot when the board is working. The temperature goes high up to 45 degree Celsius. Is that normal or it should not be like that? Do you have any idea what have caused the high temperature? 

Thanks

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BOOSTXL-TLV8544PIR: BOOSTXL-TLV8544PIR

August 26, 2018, 5:47 pm
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Part Number:BOOSTXL-TLV8544PIR

I am trying to connect the BOOSTXL-TLV8544PIR to a LMC555 timer in a mono-stable circuit which runs four leds for 5 sec.  The circuit works fine with one 3 v power supply for the 88544pir module and another 3 v power supply for the leds and lmc555 but if I try one power supply for the entire circuit or if the 555 timer and 8544 module share a battery I have a problem.  The timer self trigger continuously, can make out a flicker in between cycles and thats it..   

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TINA/Spice/INA333: INA333

August 26, 2018, 6:26 pm
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Part Number:INA333

Tool/software:TINA-TI or Spice Models

Hi TI:

I am new to this blog and have a 'challenge' that I would appreciate some assistance in.  I have been using dual op-amps to amplify a bridge with dual strain gauges for an outdoor application. Currently I amplify by approximately 530x's and then digitize the value using a Teensy 3.2 at approx 100 hz.  I have found that I have some initial drift in values - and then after about 10 minutes - values stabilize. To try and improve stability, I purchased INA333 and have been experimenting with it.  I am struggling - and suspect it is a Common Mode issue.  Thanks to your TINA download - I tried to mimic my circuit and sure enough - I cannot get any readings from TINA!  My strain gauges are 350 ohm and I calculate that they vary by +/- 0.5 ohm for my application.  I use two different voltage supplies one for the bridge and one for the amplifier) - thinking this would increase the stability of my circuit and the noise.

I enclose my TINA export of my model.  The strain gauges are represented by R5 & R6.  I even downloaded your output vs CM model  - to try and get the CM voltage in range - but that does not seem to help.

I would appreciate some assistance in figuring out what I am doing wrong, if the INA333 is the right module for my application and how to configure the circuit.

Thank you

Andy Basacchi, P. Eng.(Please visit the site to view this file)

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LMP2231: Pin to Pin solution with NCV2003SN2T1G

August 27, 2018, 1:46 am
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Part Number:LMP2231

Hi team,

Do we have pin to pin solution with NCV2003SN2T1G?

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Precision buffer stage to handle 10m~100mV 50Hz~1kHz signal with 0.01% of error and below

August 27, 2018, 1:55 am
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Good day,

I have a challenge with my circuit that my ADC is causing load effect on my source. 

Detail on the circuit parameter

  1. Source impedance: 500ohm (part of a voltage divider circuit, using 2kohm and 500ohm to form 5:1 dividing ratio) 
  2. Source signal: 10mV~100mV 50Hz~1kHz
  3. ADC input impedance: 2.5kohm

Because of the ADC input impedance, the voltage divider resistance of 500ohm has changed to lower value and is no longer providing expected voltage ratio of 5:1. I understand I can correct this impedance matching situation by inserting a buffer stage in between them. However, I am looking for a buffer stage that will not generate error more than 0.01% of input signal. Is this possible without doing manual trimming/calibration on the buffer circuit?

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INA826: THD performances

August 27, 2018, 8:40 am
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Part Number:INA826

Dear e2e Community,

We don't see any data about the THD of our INA826.

Could you share some?

Regards,

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OPA615: 5-10ns charge time

August 27, 2018, 10:28 am
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Part Number:OPA615

Hi! I want to use the OPA as a sample and hold with a fast charge time capacitor allowing 5-10ns to charge, and also want to sample at a fast rate, meaning that I set the hold control to 1-50 MHz. Is this chip specified for this type of operation?

Thank you in advance.

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TINA/Spice/INA129: Poor extrapolation of .wav file voltage amplification

August 27, 2018, 11:45 am
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Part Number:INA129

Tool/software:TINA-TI or Spice Models

Hello,

I'm currently working on a project that requires processing of a non-uniform electric signal. Using the model for the INA129 as well as several other high precision amplifiers, i used a voltage generator with the .wav file functionality to analyze a signal similar to what I will be working with. When doing a transient response analysis, I notice that the program is not amplifying my signal directly but rather extrapolating from the original data to give me an amplified output. This works fine for a sinusoidal type of input, but for a nonuniform wave pattern, it is imposing a lot of deviation from the original shape of the wave. 

I'm looking for some sort of insight on how to reduce this deviation and/or to understand how the transient analysis is being calculated and plotted

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THS7001: Using with single supply

August 27, 2018, 2:33 pm
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Part Number:THS7001

We are designing in this THS7001 where we would normally use +12V, GND and -12V. Instead, we are wondering if we can just use +24V, and tie GND to VCC- and tie a virtual GND to the VREF_PGA pin.  There is no mention of a single supply in the data sheet. Does this part support this type of configuration?

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LMP8358: About LMP8358 replace LMP8100 question.

August 27, 2018, 8:20 pm
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Part Number:LMP8358

hi,

    My application is conference system. 

    I want to find a component it could replace an old component LMP8100.

     Through TI' s website find the LMP8358 have Similar Functionality.

     but compare the gain VS frequency Graph, LMP8100 is better than LMP8358.(see as below)

     Could you recommend more suitable materials?

thanks.

      

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INA826: Current Meter position

August 28, 2018, 12:12 am
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Part Number:INA826

Hello,Guys

This is Milav Soni.

In one of my project I have used INA826AIDGKR instrumental Amplifier.

I required high input impedance >66MOhm.

I want to just know the current meter direction when we apply Following Supply to the INA.

-> At positive Terminal Give +5V supply.

-> At Negative Terminal Give -5V supply.

So Question is , What is the current meter Direction in both +ve and -ve branch? 

in both case is it from source to INA? or is different in both the branch?

I asked this question , because I got Input Impedance is less than 66Mohm. 

Here I have attached the screen shot of my Setup.

 

I got Negative Value of "AM2" and From definition of Differential current Id = AM1 - AM2 

 = 4.95 - (-5.01)

= 9.96 uA

so Id is increase in this situation and Input impedance is decrease. I have also attached the result screen shot.

Please help me to sort out this problem.

Thank you

Milav Soni

 

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PGA112: Common Mode Input Voltage

August 28, 2018, 3:05 am
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Part Number:PGA112

Hi,

I have a question regarding -> Datasheet  9.1.1 OPAMP: Input Stage, transition between the NMOS and PMOS transistor.

Typically the offset voltage starts to show big deviations around VCC-1.5V (Fig. 66 and 67). This is different on each device, and probably also temperature dependent. On the DS the Input Offset Voltage for VCM is specified as 2.5 and 4.5.

if the PGA112 is supplied with 5V, what would the max allowed Common Mode Input Voltage be, where the Offset Voltage still doesn't show big deviations?

Thanks!

Tadeo

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Burr-Brown application notes

August 28, 2018, 4:10 am
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Hello together,

is there the possibility, that someone loads up again the Burr-Brown application note  zip files, because the original thread is not available anymore.

I would like to thank you in advance.

Greetings

Alexander

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OPAMP-NOISECALC: Noise Generator

August 29, 2018, 2:49 pm
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Part Number:OPAMP-NOISECALC

Good evening, friends!

I downloaded the noise generating tool (www.ti.com/.../sloc055a) from the Texas Instruments website (www.ti.com/.../opamp-noisecalc), however, start the file "Noise Generator.exe" crashes in Windows 7 after using a few commands, being necessary to close the application and restart it.

Please. could you help me?

I would like to know what the installation procedure should be in Windows 7, and how to use the "LabSound.dll" file?

Note: There are no problems with Windows XP.

Thankful.

Luiz

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BQ24075： About parallel use of multiple batteries

August 29, 2018, 5:41 pm
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Part Number:BQ24075

Hello.
Can the BQ24075 safely charge three or more LI-ION batteries connected in parallel?
Thank you for your answer.

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LMV321: Phase Reversal

August 29, 2018, 5:48 pm
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Part Number:LMV321

Hi,

Does LMV321 have the function to prevent phase reversal?

Best Regards,

Kuramochi

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