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LMH5401: Question about Input and Output of LMH5401

September 4, 2019, 8:12 am
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Part Number: LMH5401

Hi,

Are IN+/IN- and OUT+/OUT- completely, that is 100% symmetrical and hence interchangeable on an FDA like LMH5401? The reason I am asking is that I’m using 4 LMH5401 in SE to Diff configuration to drive a 4 channel ADC (ADS54J54) with Diff inputs. Our placement and layout works best if I reverse the polarity of the FDA’s outputs toward ADC, that is to connect OUT+ on FDA to IN- on ADC, on two of the channels. The other two channels work fine straight. In order to avoid reversal of the signals I thought I connect my SE input to IN- of those FDAs that need pol. reversal (as oppose to IN+ for the other two FDAs) assumption being that FDAs are absolutely symmetrical. Is this the case?

My signal is irregular fast pulses between +1 and -1V and not even necessarily symmetrical around DC so the polarity should be conserved.

 

Regards/Ramin

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LMH6609: Butterworth filter application consult

September 4, 2019, 8:30 am
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Part Number: LMH6609

Hi team,

   My customer is using this device to do Butterworth filter, could you please help review the schematic from customer's side? The signal frequency will be 0.3~30MHz. And they find that if they apply 1MHz signal, Vpp=0.948V, they will only get Vpp=0.825 in the VF1. Could you please help share some professional advice to  find the reason what cause Vpp's attenuation? Thanks.

(Please visit the site to view this file)

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LMH6642: The condition in datasheet

September 4, 2019, 9:07 am
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Part Number: LMH6642

In the datasheet, the condition is like RL = 2 kohm to V+/2. Where does  V+/2 come from?

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Is there a chip that measures the differential voltage (10V - 50V) and current (1-3A) passing through a wire?

September 4, 2019, 9:44 am
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I am trying to measure and control the temperature of a wire that is being resistively heated.

I am measuring the temperature based on its resistance that I determine from a voltage and current measurement. The heating is done with a DC power supply where I am varying the duty cycle of a mosfet switch to control the heating. I measure the resistance whenever power is passed through the wire, with a minimum duty cycle set so I can always monitor the temperature even if I am not trying to heat the wire. 

I am currently using the INA250 for current sensing, a voltage divider for the voltage measurement, and the ads1115. 

Is there a single chip solution that can measure the differential voltage and current with an ADC built-in (16bit)?

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LMP7721: LMP7721 bias cancellation at minus 100 C

September 4, 2019, 11:43 am
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Part Number: LMP7721

I am trying to understand if the bias cancellation in the LMP7721 which works well at -40C according to the datasheet will still work well at -100C.

I am using this amplifier with a detector which must be cooled to -100C in order to get low dark current,  and need to know if the amplifier can be mounted with it or if it must be mounted separately so that it can be warmed.

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TINA-TI: test only for RespOrg assignement

September 4, 2019, 11:47 am
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Part Number: TINA-TI

test to see what RespOrg is auto-selected for TINA-TI

will DELETE when completed

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TINA-TI: How to simulate ac coupled differential amplifier

September 4, 2019, 2:02 pm
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Part Number: TINA-TI

Hi, there.

I would like to simulate the AC transfer function of the attached circuit. I used the ideal op-amp model. I wanted to have AC coupling at the output of the first stage of the differential amplifier. However, the TINA simulator returns with an error. For some reason, it does not allow AC coupling at the op-amp output. I am attaching the source file for the circuit. Would you please comment?(Please visit the site to view this file)

Thanks,

Zhaohong

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OPA197: Regarding the output at the time of differential amplifier

September 4, 2019, 6:31 pm
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Part Number: OPA197

Hi,

In the configuration shown below, if the input amplitude is 100mVp-p,

the output will be clipped around 2.6V.

(power supply is +6V)


I thought at least 3V-0.125V = 2.875V would be ok, but is this understanding correct?

Best regards,

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LM5056A: why NC pin connect to the ground plane

September 4, 2019, 7:44 pm
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Part Number: LM5056A

LM5056A is used in 48V system. If the pin 6 NC pin is connected to the ground, it is adjacent to the VIN 5 pin, whether it does not meet the Production Compliance distance. Can I float all the NC pins?

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TLV2371: TLV2371 HBM Rating

September 4, 2019, 8:50 pm
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Part Number: TLV2371

Hi TI Experts,

I need the HBM rating for TLV2371 as below:

Example:
Model Rating
HBM Class 0A JEDEC / AEC
MM Class M1A AEC
CDM (JEDEC) C3 ANSI/ESDA/JEDEC

HBM Rating Conditions
Class 0A Failure < 125 V
Class 0B 125V <= Failure < 250V
Class 1A 250V <= Failure < 500V
Class 1B 500V <= Failure < 1000V
Class 1C 1000V <= Failure < 2000V
Class 2 2000V <= Failure < 4000V
Class 3A 4000V <= Failure < 8000V
Class 3B Failure => 8000 V

Please advice.

Thanks,

Br,

Teach Me

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AMC1301: AMC1301 for Isolated 4 to 20mA current measurement - Differential Input

September 4, 2019, 9:17 pm
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Part Number: AMC1301

Hi,

Planning to use AMC1301 for Isolated 4 to 20mA current measurement with differential Input. Proposed schematic and Sensor data sheet is attached. Request to confirm whether all connections are correct or not.

Note:

1) GND1 of AMC is NOT connected to IN- 

2) GND1 is not connected to GND of sensor.

Will this work? (Please visit the site to view this file)

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TLV2333: Allowable reflow times and flatness of lead

September 4, 2019, 10:01 pm
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Part Number: TLV2333

Dear Support Team

Kindly please advise about TLV2333IDGKR.

1) How many times reflow soldering is allowed ?

2) How is the flatness specification of lead pin ?

Your kind advice is appreciated.

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AMC1200-Q1: AMC1200 vs AMC1200B vs AMC1200-Q1 different

September 5, 2019, 12:03 am
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Part Number: AMC1200-Q1

We like to use AM1200 for voltage monitor, please help to Description different for AMC1200 vs AMC1200B vs AMC1200-Q1 ,thanks !

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LM8261: how much current on positive input?

September 5, 2019, 2:20 am
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Part Number: LM8261

Hi.,

my customer enables a VDD_2V5_CASC using TPS22968 analog voltage switch and then using LM8261M5 to generate a 1V supply that is able to both source and sink current. From this 1V supply some 50mA current is used by the load.Having some issues they decided to change to TPS22976 which has a current capacity of 6 Amps instead of the 4A of TPS22968 and they saw some improvement but still have trouble with many of their boards. Now the questions are:

  • How much current does LM8261M5 use on positive input?
  • How much ripple on the output voltage should we expect from TPS22968 and TPS22976 and would this change with the current drawn?

Thanks

Fred

 

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ultra low power instrumentation amplifier

September 5, 2019, 3:48 am
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OPA690: OPA690 power design

September 5, 2019, 3:57 am
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Part Number: OPA690

Hi Team:
    My customer use OPA690 and wants to do the application of active filters. The input signal is negative pulse signal with the range of -10mV to -1V.  Please help confirm its power supply mode, Is ± 2.5V or ±5V appropriate?

   Thanks!

Regards!

Thanks!

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THS4531: VOCM voltage divider

September 5, 2019, 6:49 am
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Part Number: THS4531

Hello,

I'm planing to use the THS4531 with reduced output common mode voltage. For that purpose I connect a pull down resistor to the VOCM-pin.

I tried this for the THS4532 which in principle should behave the same as the THS4531 - am I right?

When comparing the datasheets of THS4531 and THS4532, I find differet values for the internal VOCM voltage divider :

60k (THS4531, page 33) vs 625k (THS4532, page 26)

These values differ a lot from each other and are even different to that in the electrical characteristics section which gives an input impedance 100k @ 2.7 / 100k @5V at the VOCM pin.

Thus I did some measurements on the THS4532 @3.3V / 2.75V, which gave me approximately 440k resistance of the two voltage divider resistors or equivalent 220k input resistance on the VOCM pin.

Could you please confirm this value (also for the THS4531).

How stable is this value over different samples and temperature?

Thanks in advance and best regards,

Guenther Mader

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OPA197: OPA197: Regarding the output at the time of differential amplifier

September 5, 2019, 5:54 pm
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Part Number: OPA197

Dear Thomas-san,

Thank you for your response.
I understand the contents.

However, which item in the data sheet can be understood that Vo1 and Vo2 output is clipped at about 5.77V and 230mV?

Best regards.

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LMH6644: What does Vcm=Vo=V+/2 mean? andRL=2kohm to V+/2?

September 5, 2019, 7:22 pm
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LMV796: How to select OPA

September 5, 2019, 8:52 pm
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Part Number: LMV796

If power stage working frequency around 500KHz, how to select right OPA for Current detect real-time ?

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