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Searching suitable quadruple op amp as buffer for ADC

March 20, 2019, 2:15 am
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Hello,
I searching a suitable rail to rail quadruple op amp with minimum offset and a negative rail swing very close to GND. I want to use two of them as buffers for an ADC (MCP3204).
I have a 5V single supply voltage and tried to use the LMV324 - but the output swing of the negative rail is about 50mV without 0V signal input.
That is to much for my application because it's a zero based measurement. Is there an opamp with better data for my application or what can i do instead?

Note:
I need rail to rail because i want to drive with the other two op amps two logic level Mosfets. In fact this capability is working with the LMV324

Best Regards
Wolfgang

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Square to sine for sound analog input

March 20, 2019, 11:51 am
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Hi Team,

We plan to use a OP to achieve square to sine for sound analog input.

Our frequency is about 20~20kHz, and PWM voltage is 1.8V.

Please kindly suggest suitable OP solution.

Thanks

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AMC1300: Isolated Voltage Sensing with AMC1303x25x vs. AMC1300B

March 20, 2019, 12:49 pm
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Part Number:AMC1300

Hi,

The AMC1303x25x recommends the use of an extra resistor in series with the AINN input to minimize the error caused by the input bias current, when using the amplifier for isolated voltage sensing (R3' in Fig. 55 of AMC1303 datasheet). Other isolated shunt amplifiers, specifically AMC1300B and AMC1100, do not mention this requirement.The AMC1300B datasheet doesn't actually discuss isolated voltage sensing at all, except for recommending the AMC1311B for (unipolar) dc link voltage sensing. The AMC1300's Functional Block Diagram in the datasheet looks identical to the AMC1303's Functional Block Diagram.

I tested the AMC1303E0510 with a resistor divider of approximately 1.2MOhm and 1k, and found that the extra 1k in series with AINN was highly necessary. Note: I realize that the AMC1303x05xx isn't recommended for resistor divider voltage sensing, but that was the one I had at the time for a test board, and I'll use the 250mV version in the future.

So, my question is: is the extra resistor in series with AINN necessary on the AMC1300B (like what is recommended for the AMC1303x25xx)?

Thanks,

Andrew

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THS4531: Recommended Amplifier DC parameter test circuits.

March 20, 2019, 4:53 pm
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Part Number:THS4531

Need a test circuit to measure input offset voltage of fully differential amplifiers.

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LMH5401: LM5401 parameters test Circuit

March 20, 2019, 6:14 pm
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Part Number:LMH5401

I would like to test this amplifier.  does any one have the test circuit how to test the following parameters?

  1. Input offset Voltage
  2. Input bias current
  3. input offset current
  4. Quiescent current
  5. output voltage
  6. Power Supply Rejection Ratio
  7. Common-mode offset voltage
  8. Voltage threshold

Thanks,

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RTOS/INA223: Vout range at INA223 and total current shunt monitor solutions

March 20, 2019, 8:11 pm
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Part Number:INA223

Tool/software: TI-RTOS

Hi Sir

I have a question about "Vout range at INA223 and total current shunt monitor solutions"

The Vout range meet Supply Voltage is OK, is it right?

Thanks for your great support.

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INA128: Datasheet Spec for Settling Time, Input Range

March 20, 2019, 9:34 pm
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Part Number:INA128

Hi,

Does anyone know how the settling time for INA128/129 was measured or spec'd? When filling out the datasheet, what was the output swinging from to arrive at a 9 us setting time? I only ask because I plan on swinging the output from the positive rail to ~3 V, so I was hoping to understand what the settling time might look like for a transition like that.

Also, a question about the input voltage ranges. The spec for input common mode voltage range (which I understand to be the average of the inverting and non-inverting inputs) has a max of 1.4 V lower than the positive rail, but the datasheet also says that the inputs are protected to +/- 40 V. My question then is what happens then if the input (V+ - V-) is at 40 V, which surpasses the spec for input common mode voltage? How will this affect the behavior of the amplifier?

Regards,

Michael 

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OPA735: The voltage ripple of the REF5025 and OPA735 for ADS1282

March 21, 2019, 1:38 am
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Part Number:OPA735

Hello sir,

Thanks for your answer before. But now， I meeting a new problem in my design. Please have a look.

follow circuit refer to Page 18 on datasheet of REF5025; http://www.ti.com.cn/cn/lit/ds/symlink/ref5025.pdf

If the ads1282 don't work, the voltage of +2.5VREF and -2.5VREF is very stable and high precise,but when the ads1282 begin to work ,the ripple of  +2.5VREF and -2.5VREF too bad. so do you have any suggestion about this or any other scheme about get high precise negative voltage reference.

thank you very much!

Best regards!

Kevin

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OPA830: Differential Input voltage absolute limit

March 21, 2019, 2:49 am
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Part Number:OPA830

I am in a situation where I need to replace an obsolete op amp with a new op amp. I intended to use the OPA830 as this looks to be the best op amp as a replacement however during board test this op amp may see a differential voltage of +5V which is greater than the maximum stated in the datasheet. If the current is limited at the input will the op amp be protected from damage? If so is <30mA protection enough?

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OPA4172: Is there any selection guide of amplifier I could use for my sensor signal processing?

March 21, 2019, 4:31 am
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Part Number:OPA4172

Is there any selection guide of amplifier  I could use for my sensor signal processing?

I have no idea how to select an proper OP for my sensor, for example, I cannot configure which parameter is better for my design.

May you do me a favor to offer me some selection guide of OP?

Thank you!

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INA240-SEP: negative rail current measurement

March 21, 2019, 6:44 am
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Part Number:INA240-SEP

hi,

Is it possible to measure the output current of negative rail in  +/-15V DC-DC converter using INA240-SEP current sense amplifier?

If possible please explain the connection?

thanks 

Arun

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INA240-Q1: Part No difference

March 21, 2019, 6:46 am
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Part Number:INA240-Q1

Dear TI team:

    What's the difference between INA240A1EDRQ1 and INA240A1QDRQ1？

    Thanks！

Regards！

Eric

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TLV3012-Q1: ESD information not in datasheet

March 21, 2019, 12:32 pm
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Part Number:TLV3012-Q1

TLV3012AQDCKRQ1

TLV3702QDRG4Q1

TL331QDBVRQ1

For these three Comparators, the ESD ratings have been omitted from the most recent datasheets, even though the Qualification Summary page for each device shows the following:

Qualification summary for:

TLV3012AQDCKRQ1

Note that the non-Q1 version of the datasheet does contain this information; for example, the TLV3012 datasheet www.ti.com/lit/ds/symlink/tlv3012.pdf  shows:

ABSOLUTE MAXIMUM RATINGS(1)

Supply Voltage .................................................................................... +7V

Signal Input Terminals, Voltage(2) ........................... –0.5V to (V+) + 0.5V

Current(2) .................................................. ±10mA

Output Short-Circuit(3) .............................................................. Continuous

Operating Temperature .................................................. –55°C to +150°C

Storage Temperature ..................................................... –55°C to +150°C

Junction Temperature .................................................................... +150°C

Lead Temperature (soldering, 10s) ............................................... +300°C

ESD Rating (Human Body Model) .................................................. 2000V

 

Please provide this info in Reply, and update the datasheets to reflect this information.

Thank you,

~Leonard

 

 

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TLV2474: ESD Information Missing In The Datasheet (Multiple Devices)

March 21, 2019, 1:59 pm
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Part Number:TLV2474

Hello e2e,

Quality and Reliability folder states to look in the datasheet for ESD, HBM CDM, details for the following devices but details are not in the datasheet.

TLV2474

TLV2472QDRQ1

TLV274QPWRG4Q1

TLE2071AQDRG4Q1

Please provide and update the Datasheets.

Thank you.

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INA138: Looking for lower Iq than INA138

March 21, 2019, 11:07 pm
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Part Number:INA138

Hi Sir,

Customer looking for lower Iq than INA138 parts, do you have recommends?

INA138 Iq=25uA, the target is around 5uA.

Thanks, Ian.

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TINA/Spice/OPA211: not work well when single supplied

March 21, 2019, 11:26 pm
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Part Number:OPA211

Tool/software:TINA-TI or Spice Models

Hello, I did the simulation with OPA211(sboc250c), the circuit worked when it was dual-supplied, while seemed not work well when single-supplied. The datasheet said that “The OPAx211 series is specified over a wide dualpower supply range of ±2.25 to ±18 V, or for singlesupply operation from 4.5 to 36 V”. So, can anyone help to tell how to understand it?

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TL074: temperature drift related to the load resistance

March 21, 2019, 11:27 pm
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Part Number:TL074

Hi,

My customer is using TL074 to measure 230V AC voltage. When the temperature rise from 20C to 80C, the voltage measurement result they got deviate about 10V.

Then they tried decrease RC10 and RC16 from 20k to 1k, the deviation is just 5V.

Why would this happen? Are there any inappropriate point in the schematic below?

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OPA4388: Quad Amp for SE to DE signal conversion prior to AD conversion

March 22, 2019, 1:40 am
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Part Number:OPA4388

Hi,

i'm looking into OPA4388 quad channel device for converting single ended(SE) signal into differential ended(DE) input prior to feeding the signal into 1Msps 16-bit SAR ADC. Is this a good device to implement SE to DE conversion? Will this be an overkill in terms of design specs? And assuming this device is suitable i presume i'll need 2x OPA4388 to get this done if i'm working with a quad channel 1Msps quad channel simultaneous ADC?

FYI I'm having SE input for analog side of board pumped into Delfino's 16-bit SAR ADC for conversion. Link to the discussion as follows. Thanks.

https://e2e.ti.com/support/microcontrollers/c2000/f/171/t/777758

Regards,

Leo

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hydrophone fully differential amplifier (differential input, differential output)

March 22, 2019, 4:25 am
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Can anyone help with a reference design for a fully differential amplifier for a hydrophone (piezoceramic element)? It need to be differential input and differential output as signal needs to be transmitted over long lines. Thank you

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MAX478C/LT2178 need alternative

March 22, 2019, 5:10 am
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I need an alternative for the above mentioned part .  i find an alternative from TI OPA2197/ OPA2196, but it has higher Iq current . need other suggestions 

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