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LM393: High voltage dc comparator

August 29, 2019, 6:40 am
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Part Number: LM393

Hi!

I am trying to design a comparator circuit for monitoring the voltage across a dc link capacitor(Vdcl) of a motor controller using LM393.

The output of comparator should change at Vdcl=60V DC and the maximum value of Vdcl is 85V DC. 

Power supply will we drawn from a 12V battery.

The are many op-amps available but with a very low input voltage range so a voltage divider circuit needs to be employed, but I am not sure how it is going to affect the HV circuit.

Also the voltage Vdcl is between two lines of the HV but the input to the comparator is single ended.

So, I want to know :

  • Is LM393 a right choice for the application or is there a better option?
  • Will the simple voltage divider arrangement affect rest of the HV circuit?
  • How to use this double ended HV voltage as input to a comparator?

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LMH6559: Typical Schematic

August 29, 2019, 6:55 am
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Part Number: LMH6559

Hi all,I use LMH6559  to assure that the excitation signals have low impedance

And I have some questions about LMH6559 Typical Schematic

1.What does the oval marked by the red box mean?

2.In AC circuit, it is necessary to have the components marked by blue box ?

3.The figure 1 below shows that the test circuit load is 50. In other values of the load, does the value of the resistance component marked by the green box of the circuit need to be changed?

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LF398-N: Sample and hold circuit with the LF398S8 is not working

August 29, 2019, 7:12 am
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Part Number: LF398-N

Hello everyone,

I am using a LF398S8 Sample and Hold Amplifier and am trying to give it an analog signal in the range of 0-10V that the SaH should hold on logic low and sample on logic high.

I am giving it the required supply voltage of +/- 15V and am changing the logic input that I hooked up at pin 8 every 5 sec. Logic high is 5V.

Pin 7 is grounded and on pin 6 I am using a 10nF capacitor. As an anaolg input I am using 5V for testing. However once I start giving it my logic input. The output always stays at about 0.7V.

Can someone tell me what on my circuit went wrong or is the SaH that I am using not the correct one for this application?

I am looking forward to any help I can get. 

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LF411: Equivalent input noise voltage

August 29, 2019, 7:24 am
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Part Number: LF411

Hi E2E,

Good day. 

The LF411CP is the suggested replacement for the obsolete device LF411CN/NOPB. From the  LF411CN/NOPB datasheet, the equivalent input noise voltage is typically 25 nV / √Hz where the test condition is f=1 kHz Rs=100 ohms. There is also a graph showing the relationship of equivalent input noise voltage vs.frequency.

Taking a look into the datasheet of LF411CP,  the equivalent input noise voltage is typically 18 nV / √Hz where the test condition is f=1 kHz Rs=20 ohms. Our customer is looking for the equivalent input noise voltage value where the test condition is f=1 kHz Rs=100 ohms and also for the graph which shows the relationship of equivalent input noise voltage vs.frequency. 

Thank you.

Regards,
Carlo

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LF398-N: Sample and hold circuit with the LF398S8 is not holding the input

August 29, 2019, 7:27 am
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Part Number: LF398-N

Hello,

I am trying to use a LF398S8 sample and hold amplifier that I am giving an analog input Signal in the range of 0-10 V. However the output I receive always settles at about 0.7V no matter if I change the logic.

I am giving the SaH +/-15V Supply Voltage. Pin 8 is my logic input of 5V in order to sample and 0V in order to hold my analog signal. I a switching in the period of 5 sec. On pin 6 is a Capacitor of 10 nF.

The offset and pin 7 are grounded. 

I will appreciate any help you can provide me with.

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TAS2562H-03

August 29, 2019, 7:05 pm
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THS3061: OPA inquiry for high frequency power design

August 29, 2019, 8:05 pm
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Part Number: THS3061

Hi Sir

We are going to design buck circuit by discrete solution.

For compensator part of high frequency power(10~20MHz) , does TI have any OPA for this kind of application ?

Or large bandwidth OPA for high frequency power design ?

Thanks in advance.  

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PGA309: OWD bit

August 30, 2019, 12:38 am
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Part Number: PGA309

Hi, 

In the user's guide I read :

"In four-wire module applications, it is essential that the OWD Bit (Register 4 [D15]) be set to '1' to disable the One-Wire interface after final programming is complete and before the final sensor module is sent out to the end application."

I already use a Pull-up on the PRG pin. Should I set this OWD bit to "1" in this case ? Because when I set OWD to "1" after calibration the sensor doesn't work (maybe due to this pull up)

Do you have some pieces of information ?

Thx

Guillaume

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INA240: Non-Linearity Error Imapact

August 30, 2019, 2:13 am
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Part Number: INA240

Hi Team, Please let us know which parameter will be affected by non-linearity error. (for example: Current sense input, Gain,input offset voltage or reference input voltage). Suggest a formula to calculate output voltage by considering errors seperately (Instead of sum of squares method).

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TLV316: tlv316 as comparator

August 30, 2019, 2:48 am
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Part Number: TLV316

Good morning,

i would like to use TLV316 opamp as comparator instead of finding for a comparator with push-pull output. My supply voltage is 5V, my input common mode voltage range is between 0V and 4V and the required output is about 5V or 0V depending on the comparison between the two inputs.

Are there some precautions or critical issue for this component if I will configure it in this way?

Thank you.

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LMV321A: Is LMV321AIDCKR p-p with LMV321IDCKR

August 30, 2019, 3:48 am
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Part Number: LMV321A

Hi sirs, 

Is LMV321AIDCKR p-p compatible with LMV321IDCKR?

What's the difference and advantage for A-version?

Thanks a lot!

Best Regards, 

Sean Liao

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THS3121: Short Circuit Protection

August 30, 2019, 6:02 am
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Part Number: THS3121

I'm trying to verify whether or not there is internal short circuit protection on the output of this opamp. We're using it for a pulse per second (20us PW) but there are requirements for short circuit protection.

Currently, we're just limiting the current via a resistor and doubling the voltage output (20Vpeak into a 100 ohm load, 50 of which we are providing in series to limit the current in the event of a short circuit). However, we're running into troubles with rise time due to other factors.

In order to reduce the rise time, we're looking at removing the series resistor and just have the opamp go to 10Vpeak right into the 50ohm load. However, that means there will no longer be the current limiting resistor in series. So I want to know if the opamp can handle that short for short durations or is it not equipped to handle it?

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TLV4021: Comparison with the TLV9001

August 30, 2019, 8:00 am
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Part Number: TLV4021

Hi team,

I had asked for a cheaper alternative for the LMV822-N and I got as a suggestion to look at the TLV4021 comparator (+reference family), but I recently bumped into the TLV9001IDCKR.

Do you believe the TLV9001IDCKR is a good substitute to the TLV40x1 family? Does it have any drawback?

Thank you in advance for your support.

Best regards,

Adrian

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LMH6559: LMH6559 Schematic

August 30, 2019, 8:47 am
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Part Number: LMH6559

Thanks a lot to Sean for answering the last question about LMH6559 typical schematic.But I still have some questions.

1.How does the coaxial cable connect to the conductor at the cross 1、 2、 3 with the red mark?   Is it to strip the insulation cover off a coaxial cable and expose the copper conductor, connect the copper conductor of coaxial cable and conventional wire?

2.Where does the VEE come in? Is it just that enter directly from pin 5 without going through other components or conductors?

                                       coaxial cable

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TLV9061: Looking for a small (

August 30, 2019, 10:11 am
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Part Number: TLV9061

I'm looking for a tiny FET op-amp for a photodiode preamplifier application.

1.  Single Supply - 3 volts typical.

2.  Low input current comensurate with JFET input op-amp, 10 pA typical.

3.  At lease 4  MHz Gain Bandwidth Product.

4.  For use in battery powered application, low Iq.

5.  Rail-to-rail.

6.  Shutdown pin.

7.  Single ok.

8.  Die form ok.

The TLV9061 is perfect and is 0.8 mm x 0.8 mm, packaged, except it's a little too big (I'm hoping for 0.5 mm x 0.5 mm).

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TLV1702-Q1: Window Comparator Output is High When GND Disconnected

August 30, 2019, 11:32 am
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Part Number: TLV1702-Q1

The Above Circuit is Designed to satisfy below requirement:

1. HIGH FOUT When LED Is Normal

2. LOW FOUT When LED is Fail Open

3. LOW FOUT When LED is Fail Short

4. LOW FOUT When VCC is Disconnected

5. LOW FOUT When GND is Disconnected.

High Signal Corresponds to 10V or Higher, Low Signal Corresponds to less than 5V

The above Circuit is able to satisfy all the 1-4 Requirements.However, when the Ground is disconnected, it is reading High 12V Signal.

What Changes are required to make it LOW when GND is disconnected.

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TLV1805-Q1: Marking Question

August 31, 2019, 1:23 am
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Part Number: TLV1805-Q1

HI,

My customer reported that they found two device markings on TLV1805-Q1, those are 1PJF and 1ULF, but there is no 1PJF according to our datasheet, so what's wrong here? Thanks. 

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INA240: INA240

August 31, 2019, 3:25 pm
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Part Number: INA240

Hi All

How does one paste a schematic or a pictorial in this post?

Regards

ik

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TLV3012: Instability on power on

September 1, 2019, 10:33 pm
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Part Number: TLV3012

See the schematic.

We build a battery monitor base on TLV3012. The battery is a Hybrid Supercapcitor Varta HVC series. The charge voltage is 5.5V.

The battery monitor is ON over 5.2V and OFF under 4.0V. The battery is connected to a the comparator by a switch. The comparator drive a P-MOS that distributes power (Vsupply) to a DC-DC (U5 : TPS63000). The input divider resistors are 4M64 and 1M87 on the input -. The feedback resistors on the input + are 127k and 1M87.

In some not reproductible cases, the system starts to oscillate. We succeeded to limit the oscillation by delaying the U5 start time but it still occurs. When the system oscillates, the power consumption grow up to about 500mA instead of the typical 2mA. This current are consumed by the TLV3012 itself and it finally burns.

Could you please check the schematic and give me a feedback about this phenomenon.

Thanks in advance

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LMH5401: LMH5401

September 2, 2019, 12:17 am
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Part Number: LMH5401

Hi! I have a question about power supply of Dif. Amp. LMH5401. 

There are 2d and 3d harmonic distortion (HD2 and HD3), CMMR and PSRR graphs for split-supply +2,5 V and -2,5 V. Can i believe, that when i use single supply +5V,  harmonic distorion HD2 and HD3, CMRR and PSRR will be the same as for split-supply +2,5 V and -2,5 V?

Thank you,

Anton

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