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TIDA-00555: Reference design voltage measuring circuit

September 20, 2017, 2:55 am
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Part Number:TIDA-00555

Hi 

I'm Thilesh De Silva From Sri Lanka. I'm a Research assistant in CodeGen International and currently i'm working on a project in developing a high power DC to DC Converter.

In order to measure voltages in my converter i hope to design a circuit like TIDA-00555 Reference Design. This question is about the Figure 10 ( Circuit Diagram of U Voltage Input) in the design guide.I don't exactly understand the requirement of R65, R63 and C55 and how to come up with those values if i want to change the range of  the measuring voltage. I really appreciate you'r help. Thank you 

Rgds,

thilesh

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INA116: low input impedance?

September 7, 2017, 7:28 pm
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Part Number:INA116

 

INA116 instrumentation amplifier shows unexpectedly low input impedance (<1Mohm)

I put 2 V pp signal to VL through 1Mohm resistor and only get 1 V on the input, as I'd get from resistor divider with 1Mohm INA116 resistance to ground.

This value of input impedance is indirectly confirmed by other measurements taken on other parts of the circuit (not shown here) 

Datasheet calls for >10^15 Ohmi input impedance, both differential and common mode.

Any thoughts are greatly appreciated

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OPA4277: OPA4277 for the internal schematic

September 21, 2017, 2:07 am
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Part Number:OPA4277

Hi team,

The customer would like to get the internal schematic of the OPA4277 device.

Can we provide this for the customer?

Best Wishes,
Mickey Zhang
Asia Customer Support Center
Texas Instruments

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TINA/Spice/AFE031: modifying "two node plc system" tina simulation for DC plc applications

September 20, 2017, 9:53 pm
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Part Number:AFE031

Tool/software:TINA-TI or Spice Models

hi,

I've gone through the reference design of DC plc from TI and I've downloaded the Tina spice model "two node plc system" which contains two AFE031 modules and coupling circuitry connected through a transmission line.

As my target is PLC over DC line i'm trying to modify this simulation. I am trying to start with modifying the coupling circuitry i.e, remove the coupling circuitry given in tina model and replace with coupling circuitry from DC PLC reference design . so i'm removing these two coupling circuits in the tina model and replacing with the two coupling circuits from DC reference design.

  

can some one with experience in working with this tina model comment on the changes i'm making  and the final model's ability to reflect DC PLC design.

Thank You.

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LM6142: LM6142BIMX Vos over temp spec(-40C to 85C)

September 21, 2017, 6:31 pm
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Part Number:LM6142

Hello Team,

I have one question about LM6142BIMX Vos@12V DC power supply, what's the max vos spec over temp spec(-40C to 85C)? My customer want to confirm if the max Vos < 3.5mv, please help to check, thanks.

Regards,
Nanfang

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INA114: Reference Pin Voltage

September 22, 2017, 4:43 am
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Part Number:INA114

Hi there,

I need a low cost alternate to AD8220 INA of Analog Devices. So, I'm planning to use INA114 to amplify the input signal with gain around 20 while the bipolar differential input signal will be in the range of 70µVp-p to 5mVp-p. I need minimum CMRR to be 100dB or 120dB will better on DC to 60 Hz with low offset voltage & drift.

My aim is to design a low cost Electromagnetic Flow meter.

Can INA114 be used as an alternate to AD8220?

If yes,

Since I'm using ADS1220 ADC and this doesn't allow me to pull out the internal band gap reference. Can I connect reference pin of INA114 (i.e. Pin No. 5 of 8-Pin DIP) package to a 1M resistor voltage divider with supply 5V (~2.5V at REF Pin with a parallel coupling capacitors of 10µF & 0.1µF for noise suppresion)?

else,

Can you suggest me good low cost alternate INA?

You can visit  for brief detail of my application.

Thanks & Regards,

Harish

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OPA313: Absolute Minimum Supply Voltage

September 22, 2017, 12:57 pm
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Part Number:OPA313

Hi,

My customer would like to know the absolute minimum supply voltage for the below parts.  Datasheet shows 1.8V to 5.5V recommended operating range but they are using a LDO that has 1.8V +/-0.4% tolerance output as supply voltage.  Will this be ok?  Else, what other solutions do you recommend?

Thanks,

Chuchen

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TLV8812: Op Amp - Recommendation

September 24, 2017, 12:00 am
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Part Number:TLV8812

Hello,

I looking for Op Amp, Similar to the TLV8812/11 characterises, with an enable pin, could you help me and recommend? 

best regards,

Shahaf

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OPA4314: OPA4314

September 24, 2017, 5:20 am
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Part Number:OPA4314

Hello,

For our application, we must design a simple filtering circuit consisting of a 50/60Hz notch filter to remove ground noise, followed by a 10KHz low pass filter.

The design parameters are:

VCC: 3.3V - battery powered device

Frequency range of interest: 100 Hz to 10 KHz

Vin: 0 to 3.3VPP sine wave

In the attached TINA file, the filters has been calculated with Filter Pro. Using an OPA414, when the input signal amplitude reach around 300 mVPP, the 50/60Hz notch filter output start distorsion.

The same issue appears using a Twin T 50 50/60Hz notch filter using the OPA414 implemented on the PCB prototype's. So I suppose that this op amp is not the right choice and I should really appreciate your recommendation for this application.

Awaiting your soon reply, I already thank you.

Kind Regards,

Guy BERWART

(Please visit the site to view this file)

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TINA/Spice/ACF2101: ACF2101 & Virtual Ground?

September 24, 2017, 3:20 pm
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Part Number:ACF2101

Tool/software:TINA-TI or Spice Models

Greetings,

I'm trying to get an ACF2101 set up for integration of a voltage signal, although that's not the recommended use of the product.

Using TINA-TI, I've imported the ACF2101m model and began playing with it. For logistics reasons, it is easiest for me to set up the power supply of the op amp with a virtual ground at 10V, where +20V goes to the V+ pin, GND goes to the V- pin, and +10V goes to the GND pin. My intent was to use the TLE2426 for the virtual ground, however there is no such model in TINA-TI, just the TLE2425. Regardless, attached is my current schematic. Although my hold pin is set to high (5V), which should place the chip in integration mode, no such thing happens. The resistor R1 is chosen to provide 100uA which should lead to a short integration time according to the datasheet.  Can anyone provide help? Attached is my SPICE model and relevant output. (Please visit the site to view this file)

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AMC1301-Q1: Absolute maximum voltage rating of differencial input

September 24, 2017, 5:49 pm
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Part Number:AMC1301-Q1

Hello Team,

What voltage is absolute maximum rating of the differencial input voltage(VINP-VINN)?

Though this spec is not shown on datasheet, how should we think about it?

Best regards,

Hidekazu Someno

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OPA1612: Input offset voltage

September 25, 2017, 12:34 am
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Part Number:OPA1612

We are using the OPA1612 in an instrumentation amplifier configuration. My question relates to the input offset voltage - is the input offset voltage of both devices in a dual device likely to be of the same order of magnitude or can they be widely different. My issue is not with the absolute value but the likely difference in the parameter between the two devices in a dual package.

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Strain-gauge measurement

September 25, 2017, 6:36 am
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Hello all,

I'm searching for a One-Chip solution to measure a strain signal.
I have looked at the PGA308 and PGA900, which from my Point of view are nice choices.

Does anyone of you has experience with those ICs or maybe a better choice?

My requirements are:

Less space
programmable gain
programmable Offset compensation
low power
high precision
temperature stable
max. Temp 125°C

Output Signal can be analog or digital

Thanks in advance

BR
Markus

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AMC1301: VDD2 3.3V or 5V question

September 25, 2017, 9:23 am
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Part Number:AMC1301

Hi Bros,

My customer prefer using 5V for AMC1301's VDD2. So I would like to double check with you whether 5V is OK.

In addition, We also want to check if VDD2 change to 5V, whether our Figure 24 will change? For example, when differential input voltage is 250mV, whether VoutN is higher than right now( about 2.5V)?

Thanks.

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TLV2404: The present mail is to request you with the most attentive way the contact of someone of the TI specialists in opamps with the aim

September 25, 2017, 10:18 am
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Part Number:TLV2404

Dears persons:
Let me introduce myself, I am Jose Vega from the Mexican company IUSA, first of all, good day to everybody. For our water meter without moving parts we already have a conditioning PCB where we use operational amplifiers of your recognized company, it already has a good operation in the desired operating range.

The present mail is to request you with the most attentive way the contact of someone of the TI specialists in opamps with the aim that he could support us to kindly review our circuit so that he could gives us any comment or recommendation that considers important.
Thank you very much for your support.
Jose Vega
IUSA, S.A. de C.V.
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AMC1200: with Breakout board, RC filter for DC operations, Humidity and related questions

September 25, 2017, 3:06 pm
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Part Number:AMC1200

Hello,

I am building a digital current sensing solution, for which i am using AMC1200 for amplification of low voltages of kelvin shunt resistor and reading them via MSP430FR5994 differential ADC. Below is my current schematic around AMC1200.

Please note that, all components of this schematic are surface mount, soldered on breakout board. Since rest of my design is through hole, i have converted this design to through hole with the use of DIP breakout board.

I have few questions regarding this design.

1. Is it safe to use the breakout board approach? Will it affect the accuracy or performance of AMC1200? I am placing capacitors and resistors as close to AMC1200 as possible.

2. Since operation of system is purely DC, i plan to use 15Ohm and 10uF input RC filter, so that i get approx 1KHz cutoff frequency. ( fc = 1/(2*pi*R*C) ). Are my calculations correct for filtering AC noise?

3. I have not used RC filter on output side. But datasheet example designs (page # 15,16) have output RC filters also.

Is it necessary to use output RC filter? My microcontroller is less than 80 mm far from AMC1200 breakout board. If yes, then what values of output filter, and how close to microcontroller?

4. I had bought this AMC1200 from mouser.com, and its casing had some info written over it, such as number of hours before which IC should be soldered after opening the case. And some information related to humidity restrictions also. I have opened the case around 4 months back. Does that render my IC useless, as the case mentioned soldering IC within a week. ?

5. I am using same +5V source for high side and low side (converted to +3.3V via AMS1117) supplies, and GND1, GND2 are also taken from same ground plane. Is it okay to do that? I don't need isolation as my load (high power LEDs) and other circuit probably won't generate fluctuations.

Thank you for your time and help in answering my questions.

Regards,
Hard Patel

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TLV8802: output crossover distortion

September 26, 2017, 12:37 am
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Part Number:TLV8802

Dear Specislists,

My customer is considering TLV8802 and has questions.

Could you please advise?

---

(1) Generally, optput stage is AB class push-pull.

Can I think TLV8802 is the same?

(2)Is there a possibility that distortion will occur due to charge / discharge current to the capacitive load, equivalent to class B or class C operation?

(3)According to the datasheet, when capacitive load is heavy(>50pF), it is recommended to add Riso.

In this case, is there a possibility to increase output distortion?

---

I appreciate your great help in advance.

Best regards,

Shinichi

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TLV522: Output Crossover Distortion

September 26, 2017, 12:40 am
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Part Number:TLV522

Dear Specislists,

My customer is considering TLV522 and has questions.

Could you please advise?

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(1) Generally, optput stage is AB class push-pull.

Can I think TLV522 is the same?

(2)Is there a possibility that distortion will occur due to charge / discharge current to the capacitive load, equivalent to class B or class C operation?

(3)According to the datasheet, when capacitive load is heavy(>50pF), it is recommended to add Riso.

In this case, is there a possibility to increase output distortion?

---

I appreciate your great help in advance.

Best regards,

Shinichi

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PGA205: The noise issue

September 26, 2017, 2:34 am
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Part Number:PGA205

Hello,

 

Regarding to PGA205, my customer is asking some question.

Currently, they are checking PGA205 on their board and face noise issue.

(Please refer below.)


 

They confirmed other frequency(14kHz,20kHz) in addition input signal(17kHz) at ADC output by frequency analysis(FFT) .

To making clear to cause , they confirmed following.

(1) They configured PGA205 gain(x1,x2,x4,x8) by A0/A1 pin and confirmed ADC output data.

(Result)

Input signal(17kHz) -> The signal is output with each gain multiplier(x1,x2,x4,x8).

14kHz/20kHz -> Regardless of gain multiplier, the signal is output approximately 1 time(x1).

From above result, they think it possible that noise issue(14kHz/20kHz) won’t be occurred from the front stage of PGA 205.

(2) They confirmed noise on only ADC block by frequency analysis.

(ADC input -> GND: R312 Removed. C316 shorted to GND.)

(Result)

They couldn’t confirmed two noise(14kHz/20kHz) and input frequency(17kHz).

(Question)

Could you please give us comment, points or advice?

Is there any possible causes?

 

Regards,

Tao2199

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LMH6321: SO Power Pad Connection

September 26, 2017, 11:46 am
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Part Number:LMH6321

I am not sure of how the pad should be connected with this part. Is it supposed to be connected to GND or to the lowest voltage present? I am assuming that my customer should use vias for this connection?

Can you also show me where the CL pin is actually connected in figure 51? My customer is asking how this pin is referenced to GND.

Thanks for your help with this!

Richard Elmquist

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