Customer is using INA220 to monitor -48V power, and shunt resistor is 1moh, max current is 12A, how to set calibration register? can list calculation process?

and if we read power register and current register , how to convert this register value to real current and power value?

many thanks

↧

LMC660: If LMC660AIMX is Pb-Free or Green?

August 30, 2018, 12:06 am

≫ Next: LOG114: I need negative input current. so i need help

≪ Previous: INA220: how to set calibration register? and how to convert register value to real current and power value?

Part Number:LMC660

Hi，

I bought parts of LMC660AIMX with date code of 1349, Pls help to check if the parts are Pb-Free or Green.

Thank you.

↧

LOG114: I need negative input current. so i need help

August 30, 2018, 12:38 am

≫ Next: INA210: INA210 burn down during normal operation

≪ Previous: LMC660: If LMC660AIMX is Pb-Free or Green?

Part Number:LOG114

Using negative bias, we want to drive log114.

I have found a circuit that can use negative bias in the datasheet.

There are questions in this circuit.

1. I want to know the mathematical formula between il and v1.

2. I would like to know the induction process of the mathematical formulas.

Thanks for your reply.

↧

INA210: INA210 burn down during normal operation

August 30, 2018, 1:06 am

≫ Next: OPA549: OPA549 Application Questions and Roadmap Advisory

≪ Previous: LOG114: I need negative input current. so i need help

Part Number:INA210

Hi,

one of my customer is having issue of INA210 burned down during normal operation, the application in this case is a current sense feedback circuit.

Please refer to below schematic capture and let us know if further information needed.

I also wonder if there are other customer have the same problem.

Thank you.

↧

OPA549: OPA549 Application Questions and Roadmap Advisory

August 30, 2018, 3:00 am

≫ Next: advice for replacement of TC75S51FE

≪ Previous: INA210: INA210 burn down during normal operation

Part Number:OPA549

Hi team,

Nice to reach out to you. My customer is doing a pre-research project and will use our OPA549, to generate a programmable low voltage and high current power source.

They have below questions which need your help:

Testing schematic:

1. Accuracy of the current-limiting resistance

Below are the measurement results:

R_CL(Current-limiting resistance)	V_CLTheory	V_CLTest	I_supply	I_outTheory	I_outTest	V_set
1870Ω	0.948V		7.25A	8A	7.11A	ref+0.95V
940Ω	0.529V	0.520V	7.91A	8.89A	7.75A
867Ω	0.492V	0.490V	8.31A	8.97A	8.16A
845Ω	0.481V			9A		ref+0.48V

If R_CL=1870 Ω, the I_outshould equal to 8A in theory, but the measurement result equals to 7.11A. Why there is the difference? What’s the error range for the R_CL?

2. How the output load influences the (V₊)-V_ovalue?

Are there any requirement for the output load? Customer tested the voltage difference (V₊)-V_ounder the I_out=8A, with the output load 150m Ω , and (V₊)-V_o=5.5V, which higher than the datasheet value, max output voltage swing is 4.3V. Will it cause any risk to the device?

They also tested below data:

When the output load increases to 300mΩ, the (V₊)-V_o= 4.5V

When the output load decreases to 10mΩ, the (V₊)-V_o= 7V

3. They want to use OPA549 in parallel. How many pieces can be connected in parallel? Considering customer will have 8A output current for 1 piece. Are there any matters which they need to pay attention to?

4. Do we have any roadmap for High-Voltage, High-Current Operational Amplifier?

Looking forward to your reply. Thanks!

↧

advice for replacement of TC75S51FE

August 30, 2018, 3:12 am

≫ Next: LMH6715: LMH6715-MDC - What type of packaging (e.g., Gel Pak, waffle pack) does known good die LMH6715-MDC come in from factory?

≪ Previous: OPA549: OPA549 Application Questions and Roadmap Advisory

Hi TIs,

I want to find a device to replace TC75S51FE,If OPA145 is good choice?

Waiting for your advice.

Thanks a lot.

↧

LMH6715: LMH6715-MDC - What type of packaging (e.g., Gel Pak, waffle pack) does known good die LMH6715-MDC come in from factory?

August 30, 2018, 10:09 am

≫ Next: TINA/Spice/OPA111: Simulated vs Actual Performance

≪ Previous: advice for replacement of TC75S51FE

Part Number:LMH6715

Our customer is interested in possibly buying LMH6715-MDC, but is inquiring on the type of packaging the die is housed in

↧

TINA/Spice/OPA111: Simulated vs Actual Performance

August 30, 2018, 11:02 am

≫ Next: OPA187: need a part with fast response time and low ripple

≪ Previous: LMH6715: LMH6715-MDC - What type of packaging (e.g., Gel Pak, waffle pack) does known good die LMH6715-MDC come in from factory?

Part Number:OPA111

Tool/software:TINA-TI or Spice Models

How accurately does the Spice model for the OPA111 represent the real life performance of the part? I need to know what might be causing differences between our experimental data and the data from simulation. Are there are any aspects of the OPA111 part not taken into account in the Spice model?

↧

OPA187: need a part with fast response time and low ripple

August 30, 2018, 12:44 pm

≫ Next: BUF634: Need your help to check BUF634 genuine

≪ Previous: TINA/Spice/OPA111: Simulated vs Actual Performance

Part Number:OPA187

Hello!

I am trying to convert a PWM output from a IR sensor to a analog signal. I am measuring temperature change in a system and i need a fast response time (is the us) and a very low voltage ripple : ~1mV. This is not possible with a simple RC circuit, so I was looking into active filters. My PWM signal swings from o to 3V and the period is 1.024ms. I can not increase the PWM frequency. Would the OPA187 work for this application?

↧

BUF634: Need your help to check BUF634 genuine

August 30, 2018, 6:39 pm

≫ Next: AMC1301: Isolation Channel Signal Transmission

≪ Previous: OPA187: need a part with fast response time and low ripple

Part Number:BUF634

I bought some SOP type BUF634s from a shop recently, but they don't work as they are and I am afraid that they are fakes. Then, I get your help to check if they are genuine parts or not.

Since they don't work, I check the conductivity between pin 2, 5 and 8 to other pins and found there is conductivity between pin 4 to pin 5 and 8 like diode. According to the data sheet, the 3 pins are not connected internally, meaning they are possibly fakes?

I appreciate your comment.

↧

AMC1301: Isolation Channel Signal Transmission

August 30, 2018, 10:39 pm

≫ Next: OPA2277: OPA2277 Input error

≪ Previous: BUF634: Need your help to check BUF634 genuine

Part Number:AMC1301

Hi all

Would you mind if we ask AMC1301?

Does the AMC1301 use an on-off keying (OOK) modulation scheme to transmit the modulator output bitstream across the SiO2-based isolation barrier?
Or, edge detection?
There is no description, however we assume that it is OOK method.

Kind regards,

Hirotaka Matsumoto

↧

OPA2277: OPA2277 Input error

August 31, 2018, 2:29 am

≫ Next: OPA189: SOT-23 package

≪ Previous: AMC1301: Isolation Channel Signal Transmission

Part Number:OPA2277

Hello to everyone,

I've developed the following desing in order to sense a high current (from 0A o 110A):

*NOTES: RL is the Load Resistor of the equipment, and IN is a signal that can vary from 0 to 350V.

As can be seen, it is intended to get an opamp ouuput of 200mV when 110A generates a voltage drop of 30mV through the shunt resistor.

The problem is I can not get the desired input in the opamp. For exaple, if I force the equipment to get a current consumption of 20A, I do not get the desired voltage drop (it is intended to be about 5mV, insted of 140mV I am actually getting).

By the way, I use a similar circuit to sense the voltage between IN and DGND that uses an AMC1311 that actually works without problems.

Any ideas?

Best regards and thanks in advance,

Álvaro.

↧

OPA189: SOT-23 package

August 31, 2018, 5:40 am

≫ Next: LMP8640HV: CMRR in PWM Mode

≪ Previous: OPA2277: OPA2277 Input error

Part Number:OPA189

Hi,

when will the SOT-23 and SO-8 package for the OPA189 be available?

Thanks

Fred

↧

LMP8640HV: CMRR in PWM Mode

August 31, 2018, 5:49 am

≫ Next: INA199: Current Leaking through the sensor

≪ Previous: OPA189: SOT-23 package

Part Number:LMP8640HV

Hi everyone,

while running a current controlled valve, we noticed some unexpected signals at the output of the LMP8640HVMK-T. There are significant spikes every time the PWM switches the high-side-switched valve on and off.

The circuit we use applies a 24V PWM to control current, which is measured by a 25mOhm Shunt, which in turn is used with the LMP8640HV-T to supply the current signal to an µC ADC.

A zoom on the negative and positive going edge provides details;

This seems to be some effect that has to do with CMRR, but it does not correlate to datasheet value of 103 dB.

Additional info:

A competitor IC with similar function performs as expected
When using the LMP8640 in a low side switching scenario, these voltage dips do not occur.

Can someone explain this behaviour and how it could have been seen from the datasheet that the LMP8640 might act this way in this particular application.

Thanks in advance and a nice weekend!

Simon Bauer

↧

INA199: Current Leaking through the sensor

August 31, 2018, 8:02 am

≫ Next: PGA281: PGA281 offset voltage limits referred to output

≪ Previous: LMP8640HV: CMRR in PWM Mode

Part Number:INA199

Hi,

I am using INA199B2 bidirectional current sensor for my project.

I powered the system with 12V battery. I had also a voltage regulator stepping voltage down from 12V to 5V which was used as a power supply for my INA199B2 chips.

After energizing the circuit I find out that the voltage supply port of INAB2 is exactly the same as my battery voltage.

I had a similar problem before when I used INA100A2. I was told that version B should be enough to solve my problems.

How can I fix it?

Best Regards,

Bartosz

↧

PGA281: PGA281 offset voltage limits referred to output

August 31, 2018, 11:41 am

≫ Next: AMC1301: Low frequency ripple

≪ Previous: INA199: Current Leaking through the sensor

Part Number:PGA281

Hi Experts

I have a question regarding offset values of the PGA281... I have 8 PGA281 in my application board , and when I shorted the PGA differential input I measure the output(output offset) and get values from ±2uV until ±200 uV , but there is one PGA which output reaches 405uV when G=64 and 559uV when G=88... From the datasheet I extracted that Offset voltage referred to input is TYP= ±(5 + 45/G) and MAX ±(20 + 235/G)...
that meas that the maximum value I could get in the output offset voltage will be ±(20 + 235/64)*64 = ±1515uV when G=64 and ±1995uV when G=88? if yes then the values I am measuring are high but are ok?

↧

AMC1301: Low frequency ripple

August 31, 2018, 11:47 am

≫ Next: AMC1302: LPRF Current Sense Techniques

≪ Previous: PGA281: PGA281 offset voltage limits referred to output

Part Number:AMC1301

Hello,

We are using the circuit below to isolate an analog signal, but at the differential output we get a constant low-frequency ripple of around 40mVrms.

We have several prototype boards, and this ripple is not consistent among all the boards. It changes in amplitude and frequency, and in some boards it's not even there.

From board to board, the amplitude changes between 0 and 50mVrms, and the frequency between 300Hz and 3kHz. In each board the ripple remains unchanged, even if we short the input pins.

Can one of the analog stages be oscillating?

Thanks,

Max