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DRV2700EVM: drv2700evm how to wiring to piezo when i want use 0-75 volt loop?

February 21, 2019, 4:02 am
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Part Number:DRV2700EVM

Hello i'm student in KMUTT Thailand and I need help. My english may be not polite i'm very sorry for this.
I want to generate volt to 0-75 Volt DC for input to piezo stack.
I already read datasheet for drv2700evm but I'm not sure i understand it correct or not.
First,I connect it to PC laptop it work normal not have error from software.(I use window 10)
I set jumper like this "JP10[msp-usb] ,JP11[usb-drv]  , JP9[en-msp]  , JP8[GAIN1:msp] , JP7 [gain0-msp]  , Jp2[Conenct] , JP3[NotConnect] , JP4[NotConenct] , JP5[Connect] , JP6[Connect] , JP12[Connect]
In page 19 of datasheet have 3 wiring .I'm not sure what kind of output can i wiring for this.

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TLV6703: Higher Speed

February 21, 2019, 4:28 am
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Part Number:TLV6703

Dear Team,

It seems this device's response time is around us level.

Do we have ns level's device?

How to select a higher speed device on our web?

BR

Kevin

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OPA564-Q1: Power Sequence

February 21, 2019, 5:18 am
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Part Number:OPA564-Q1

Hi team,

My customer considers employing OPA564-Q1 and provided a question in terms of power sequence.

He would like to use OPA564-Q1 with ±12V supply.

Datasheet describes "Sequencing of power supplies must assure that the digital supply voltage be applied before the supply voltage to prevent damage to the OPA564-Q1." and Figure.36 shows power supply sequencing.

Considering above condition, is below power sequence correct?

V-(-12V)→VIDG(-8V)→V+(12V)  

If you have other recommended sequence example or reference circuit, it should be helpful.

I look forward to hearing back from you.

Best regards,

Shota Mago

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OPA187: OPA187 SPICE MODEL FILE

February 21, 2019, 5:35 am
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Part Number:OPA187

Hi, 

I am trying to build a trsnsimpedance amplifier with a high gain to measure current as low as 0.35nA. I find OPA187 as a suitable choice for it. I want to simulate my circuit and characterise it. For that I need Spice model file for the same. 

So I tried downloading spice model file from the website of TI for TINA TI, but all the folders are empty. May I know why so? Can anyone help me in obtaining Spice model file for OPA187. 

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OPA192: Output unstable issue at 10KHz dynamic loading

February 21, 2019, 6:04 am
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Part Number:OPA192

Hi Guys:

Sorry for reply so late because of the chinese holiday. We also did some test based on our opa192 issue. You can refer the and click "Original question" at the top post.

As you mentioned before, the Rf and Rs tolerance will lead to the accuracy and harmonics. So to minimize the tolerance we also did test by using INAx serise device here. But we found the INAx device will also have the same problem. You can see:

OPA192, CH3: output current;   CH4: OPA192 output;

INA180A4 CH1: INA180 output，CH4: output current:

besides that, the gain of  INA180A4 is fixed. We can not adjust the feedback loop resistor, so the INA180 will have Steady-state error. The output voltage curve will have a little bit tolerance to the ideal value. But if we use opa192, we can adjust the Rf or Rs at the feedback loop to make the real curve meet the requirement of the ideal value.

But we use opa192, it still have the unstable issue at high speed transient condition. Seem like a blind alley. So do you have some better optimized suggestions to make it stable. Or some other device will be better at this application?

Thanks

-Pengfei

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INA301: INA301A1

February 21, 2019, 7:45 am
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Part Number:INA301

I would like to know what is the input resistance to the amplifier. So that I can calcuate the effective gain of the INA with the addition of input common and differential mode filter. Also is there a application note regarding caculating the total gain and gain error due to various factors for INA301.

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TLV6700: AC Line Input Voltage Detector

February 21, 2019, 11:05 am
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Part Number:TLV6700

Hello,

 

I’m considering how to design comparator circuit for AC input line voltage.

We need to detect if AC line voltage is within the particular range or not (198V-10% to 253V+10%).

I think the circuit on PMP4311 is similar to what we want (Please see input OVP and Input UVP at the bottom of schematic page. 2).

 

Do you have any collateral which explains how to design this circuit?

 

Best Regards,

Kazuki Itoh 伊藤　一樹

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TLV3502: Purpose of capacitive feedback

February 21, 2019, 12:30 pm
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Part Number:TLV3502

Hello,

I am referring to sheet 5 of 6 from the schematics (page 5 of the ".pdf" document) in the following link: http://www.ti.com/lit/df/tidrv40a/tidrv40a.pdf

I see that the component U406B which is a TLV3502 comparator has C415 as positive feedback. Can anyone explain its purpose and how to select its value ?

Also, can anyone explain the purpose of C408 connected between "-" and "+" of the comparator and how to select its value ?

Thank you for your time !

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TINA/Spice/LMP7721: Gain curves-not correct

February 21, 2019, 12:43 pm
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Part Number:LMP7721

Tool/software:TINA-TI or Spice Models

Hi ,

I am running some simulation to check phase margin, gain for my application for LMP7721 which I decided to use as Trans impedance amplifier for my application.

Below is what is my requirement:

BW=1MHz(min.)

Input current=400uA(max.) Output voltage=4.7V(max.)

Sensor resistor=16kohm

Sensor+ stray capacitance=1pF(max.)

However, I don't see right open loop gain. Attached is my model and graph. Please let me know if I am running simulation right way(I did check out training videos from TI website) before implementing.

Also, did I calculated right parameters for feedback?

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TLV3201: AC Line Over Current Detection

February 21, 2019, 4:54 pm
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Part Number:TLV3201

Hello,

I'd like to detect overcurrent situation of AC line input of CCM PFC.


UCC28070A is used for the PFC controller, and current detection is already performed on the low side of the MOSFET.
However, since this signal is pulsed and the minimum pulse width is 733 ns, there is a concern to use it for overcurrent detection.
We also considered inserting a resistor in the return path of the diode bridge, but since the output signal becomes a negative voltage, it is impossible to detect overcurrent with a single power supply comparator.

What is the smartest AC overcurrent detection method in this case?

Best regards,

Itoh

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TLV3201: About a simulation of TLV3201 in TINA-TI.

February 21, 2019, 5:16 pm
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Part Number:TLV3201

Hi team.

I'd like to simulate the propagation delay.

(and I want to know difference between the simulation and the data sheet.)

So, could you tell me a detailed circuit diagram for simulation in TINA-TI that will give me the results of the data sheet?

I have drew bellow schematic.

Bellow is my result.

However ,my result are different from the data sheet values at propagation delay.

Will the results of the simulation and the data sheet be close?

Could you give me some advice?

Sincerely.

Kengo.

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TL074: AbsoluteMax:　differential input voltage

February 21, 2019, 6:14 pm
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Part Number:TL074

Hi Everyone!

I have a question　about TL074 Datasheet：

There was no differential input voltage information in the data sheet of TL 074.
Please indicate the absolute maximum rating of the differential input voltage.

【Supplementary information】
In addition, although there is description in the data sheet of TL 084, TL 074 includes
There is evidence of deletion. (Please refer to the following)
I would be pleased if you could tell me why it was deleted.

"Changes from Revision M (February 2014) to Revision N
Deleted differential input voltage parameter from Absolute Maximum Ratings table"

Certainly, TL084 had a description of differential Input Voltage Max ± 30V.

If you have any information please let me know!

Best Regards

Shing

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XTR111: Mosfet & Transistor selection

February 21, 2019, 7:21 pm
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Part Number:XTR111

Hi everyone.

On the circuit diagram provided on the datasheet, there is a MOSFET and a transistor that need to be implemented separately by the end user. I've been doing some research and modeled the circuit on Tina, but I don't really know what specific components I should buy (referring to the MOSFET and transistor). Could someone please provide some advise on what I specifically need to look for?

Kind regards,

Dani

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LF398-N: LF398N issue at output voltage range.

February 21, 2019, 7:58 pm
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Part Number:LF398-N

Hi,

I am using LF398N in my application. I am facing issues with the output voltage of the S/H which is not going more than 3.3v. 

The input is varying from 0 to 5v. 

VCC is 5v.

Logic is given to switching signal whose pulse width is 1ms and period is more than 100ms.

VCM=2.5v. 

The hold capacitor also holds only maximum of 3.3v. Is it not possible to get more than 3.3v output using LF398?

Thanks

Ramesh B

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INA260: SDA/SCL pull high voltage and VS supply voltage

February 22, 2019, 7:30 am
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Part Number:INA260

Hi team,

What will happen if pull high SDA/SCL to 3.3V but VS pin supply voltage is 5V? The I2C interface function will not work?

So usually we should suggest VS supply voltage to be 3.3V which is the same with SDA/SCL?

Thanks.

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INA826: current sense amplifier

February 22, 2019, 10:25 am
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Part Number:INA826

INA826 is wired as a current-sense amplifier with a gain of 50.  The bias voltages are +5V & -4.5V.  I applied 50mVdc to the input of the in-amp.  I am expecting 2.5Vdc across the 0.01uF capacitor.

I am not getting any signal.  What am I missing please?  Thanks.

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LMH6612: Maximum voltage on output pin?

February 22, 2019, 1:21 pm
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Part Number:LMH6612

Hello all,

I am evaluating the LMH6612 for an application with ESD threats on the output. I have added protection features (Diodes, series resistor, ferrite bead) to mitigate the threat, so the output pin of the op-amp now experiences a 5.6V, 60 ns pulse during the event. Supply voltage is +/- 5V so this being limited to about a diode drop above the rail. My question is how, if possible, to best evaluate whether the event is survivable for the op-amp. Thermal analysis does not seem very helpful here since the threat is a transient.

Thanks!

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Noise analysis of Trans impedance

February 22, 2019, 1:48 pm
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Hi,

I am referring to TI paper "Noise Analysis OF FET Transimpedance Amplifier" for noise calculation of TIA .

However,I am not clear about below things:

1) For current Noise calculation:(page 4)

  • For region 1:How is 4E-9 value obtained ?
  • For region 2:How is 4E-13 value obtained ?
  • For region 3: How is 6.36E--9 value obtained ?

Also how can we draw Voltage noise density vs frequency graph for noise current ?

2) Why can't we use below formula for current noise calculation?

Eni=(Current noise density)*(Rfeedback)*SQRT(1.57*F3db)

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ISO224: Advantages of using ISO224 vs. ISO124

February 22, 2019, 1:55 pm
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Part Number:ISO224

I'm currently in need of a unity-gain isolation amplifier for my application. My investigation brings me to ISO124, and ISO224.

Available to me are two isolated supplies: +/- 15 V, and +5 V. Which amplifier is better suited for my application? Based on the datasheet for ISO124, it seems that single-supply operation is not encouraged, and that it might be better in that case to use ISO224. What advantages are there to using ISO224 over ISO124? Based on the availability of my supplies, which one will work better in my application? I'm willing to provide any additional information that might be necessary.

Regards,

Michael

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OPA2277: Matched Pair of Op-Amps.

February 23, 2019, 1:37 am
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Part Number:OPA2277

Presently we are using OPA2277 in one of our application. We would like to know how to order / identify matched pair of Op-Amp so that the output of both the Op-Amps are closely matched to each other. Presently in our testing we find that there is upto 28% difference in the outputs of Op-Amps of different lots. We have the following results displayed as ADC output.

OpAmp 1 Channel A : Average ADC count is 16904 ; Channel B Average ADC count is 15259; here the difference is 1645 [9.7 %] which is acceptable.

For the same sensor with different Op-Amp

OpAmp 2  Channel A : Average ADC count is 11028; Channel B Average ADC count is 15368; here the difference is -4340 [-28.2 %] which is un-acceptable.

Ideally, we would like to have same output for same sensor.

Kindly advice.

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