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why OPA129 cannot be used as a voltage follower, what is wrong
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Using PGA309EVM-USB to calibrate external sensor hardware
Hi
I have the PGA309EVM-USB and USB-DAQ hardware. I'd like to use the DAQ to calibrate my own sensor hardware which uses the PGA309.
I noticed that the DAQ controls the TEST input to the PGA309 on the EVM board, which is pulled up on the DAQ board.
Reading the PGA309 documentation it says that the TEST pin should be grounded for normal operation, but pulled high to allow an external uC to write to the registers. Does this mean if I want to let the DAQ program my PGA309, I need to connect the DAQ to my PGA309's TEST pin or can the PGA309 be calibrated with the TEST pin grounded?
Regards
Bob
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TLV2771 for piezoelectric material force sensor problem
Currently I want to use TLV2771 circuit to connect to our piezoelectric material. I am not sure if it fit our demand.
Actually my major is not in this field. This is all new to me. And I saw a lot of chips in the TLV2771 category, does anybody can explain the difference between each other?
And I go over the reference circuit provided on the website (www.ti.com/.../sloa033a.pdf). I want to make it working in charge mode. The attachment is the circuit we want to use. 
I wanted to double-check that I'm understanding the circuit.
My material parameter is:
Qmax=15nC
Vmax=20V
Cp=0.75nF
Desired to work in low frequency region: 0.01Hz~10Hz
And fL = 1/(2pi*Ri*Cf)
fH = 1/(2pi*Ri(Cp+Cc))
gain = 1/Cf
My calculated values are:
Rf = 500MOhm
Cf = 15nC/5V=3nF
Ri = 20Mohm
I'm not sure if my calculation is correct. And I don't know how to add the Vcc in the graph.
And i don't know how could i started to build the circuit. Is evaluation board needed besides the chips? I appreciate your help very much.
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not sure which circuit is better, please give me some advice
Dear Experts:
which one is better and has less noise?
Thank you
Best regards
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Questions about Spice model of LMV712
Hi all,
I'm looking for a Spice model of LMV712.
And I confirmed the TI Web, but it was't found.
Please let me know if you have data.
Yours sincerely,
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OP AMP Propagation delay
Hi,
Can any one help me to find the propagation delay of an OP AMP.
Regards
Hari
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Opa355 RfI
Hi I have been using Opa355 in my current products with good success. (Shipping in several K units). It is used in a Tia with 8M gain at 1MHz signal.
I recently started a new design and this design uses wifi. With the new design, I see an in band Rfi rectification due to wifi. Design is ac coupled simple transimpedance amplifier. I amplify in two stages. 400k in first stage and 20 in second. I use 1.8v as reference voltage and opamp is using 4v supply. I have very little noise and excellent signal performance when wifi is turned off.
The only issue is really Rfi rectification. When wifi is transmitting I see a DC shift in first and second stage output. Due to high gain even a small shift result in nasty output swings. The design uses high quality bypass caps on supplies, 15v bias on the pd and 1.8v reference ground. (I still see the issue when I remove the pd from the circuit so it is clearly picked up by either my ground or opamp)
- I have added 100pf to the reference pin (+) which helped but added noise.
- I tried shielding using copper tape but I cannot get reliable results. Looks like I need to build something more sophisticated but not so sure it will work.
- spin another board with other protections etc.
- use another opamp with better Rfi tolerance is the last resort I really like this opamp and don't want to change but I don't know how to move forward.
Assuming I respin the board what precautions I can take? Appreciate inputs. Thx. Kt
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Drv103 Oscillating at 1000Hz
Dear Support: I am trying to get the DRV103 to oscillate at 1000 Hz. We had it working at 20k Hz with a duty cycle of 50%. The resisters used were Rosc: 220K and Rduty 150K. Now I switched to Rosc of 5M and Rduty 1M. All I get is a 380 usec pulse, one time when the chip is enabled. I know these values are at the extremes of the tables. We are trying to operate an inkjet valve which has a maximum frequency of 1kz. I would really like to run it at 500hz.
Please let me know if there any special needs at that frequency or any application notes that are applicable.
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Integration of INA126 with sEMG and Electrical Stimulation
To Whom It May Concern:
As part of my dissertation data collection, I will be using electrical stimulation in conjunction with surface EMG. As part of my literature review, I came across an article “Evoked EMG versus Muscle Torque during Fatiguing Functional Electrical Stimulation-Evoked Muscle Contractions and Short-Term Recovery in Individuals with Spinal Cord Injury.” As part of the research protocol, the researchers used the TI INA126 Micropower Instrumentation Amplifier to amplify sEMG signals. I was wondering how I could implement this piece of equipment with my current research set up to amplify the sEMG data as to minimize the electrical stimulation interference.
Thank you for your time and any advice you might be able to provide.
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AMC1100 / calculation of accuracy
Hello,
(1) about Nonlinerarity
Since Nonlinearity is +/-0.015% , should we consider ±0.6mV as output voltage difference by nonlinearity at the condition of Vdiff=±250mV, Gain=8 , Vout = ±2V?
(2) dc voltage mesurement accuracy
Could you please let me know the caliculation of output voltage which include Vos, Vos drift, noise , nonlinearity, gain drift or other parameters for accuracy?
If there are the calculation example, please let me know.
Best Regards,
Ryuji Asaka
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LME49880 / Connect the exposed pad to V-
Hi All,
The datasheet recommend to connect the exposed pad to V-. Please let me know the reason. Is the exposed pad connected to GND potential into the package?
Best Regards,
Sonoki / Japan Disty
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should to develop an anti aliassing filter now but the sampling frequency is not determined!
Hi,
I should to develop the hardware for my embedded system.
For the anti aliasing filter, the sampling frequency is not known now. ie it wil be designed in software deveoping phase.
IS there a solution?
Or the sampling frequency must be know first?
Thank you,
Ras
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analog interface to diffrential adc; where to place anti aliasing filter?
Dear all,
I want to condition an analog signal to a differential adc channel.
I decide to use the bellow circuit ( from TI note )
Where do I should to place an anti aliasig filter?
Can I combine the anti aliasing filter with the above schematic to eliminate the extra op amp?
Regards,
Ras
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LMP7221 : PCB Layout
Dear specialist
Our customer is considering LMP7221.
We found two documents of EVM but they don't describe about PCB Layout.
Our customer want to refer EVM's PCB Layout.
Could you provide about the above?
Best regards.
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TINA-TI Simulation Phase Margin
Hallo,
Would you please let me know how to look at the phase margin in TINA-TI simulation?
I found a material of TINA-TI simulation on the negative feedback.
There are some figures as below in this material.
Is it correct that how to look at the Phase margin and Gain margin is the blue arrow on the LoopGain curve?
Best Regards,
Kazu Ogawa
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INA128 and INA333 Signal Out.
Hello,
I am using both the INA128 and the INA333 in a sensor conditioning circuit. Both have a 5V supply and pin 4 and ref pin 8 are tied to 0V. When measured with test leads at the circuit board at room temperature and atmospheric pressure the INA128 output is 0.084V, But if I add a 10ft length of cable the and change nothing else the voltage goes to 0.174V. with the cable still attached if I measure at the board the voltage is 0.174V with the cable still attached. The current draw also goes from 6mA to 10ma. Measuring the voltage to the voltage regulator is the same. (12V into the voltage regulator 5V out of the reg. ) If I move the supply to the board the voltage drops but not all the way.
Thanks,
Jim
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TL082 IBIS model
Hi! all,
Our customer plans to use TL082 and has asked for the IBIS model.
Could you please share the IBIS model for this device?
Regards,
Toshi
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OPA376-Q1/Input rail to rail.
Hi all.
There is no description of " Input rail to rail" on the data sheet of OPA376-Q1.
Does this device have "Input rail to rail"?
Best Regards,
Sho Ogane
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Open loop output impedance of INA129 and INA121
Hi,
1. What will be the open loop output impedance of INA129 and INA121?
2. Is there a way to use the INA spice model and extract the model of 3 opamps inside these INAs seperately to check the stability?.
3. How much the gain bandwidth (1.3MHz and 600KHz respectively for INA129 and INA121 at Gain=1) will change over the operating temperature?
Thanks
Shihab.
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TL064: supply voltage missing min specification
Hello,
a question regarding the minimum supply voltage came up, as there is no clear specification of it in the datasheet but on the product page there is.
product page states: 7V minimum required total supply voltage
but: in the datasheet there are graphs with respect to supply voltage, which go down below 2V, which would mean a total supply voltage of only 3.6V or something like that.
I know the part is old, but still a clarification would be highly appreciated.
Thanks.
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