WEBENCH® Tools/TSW1400EVM: TSW1400EVM

Guoming,

Make sure the 5V power supply to the TSW1400EVM is capable of providing at least 4A. After you clicked on capture, what was the status of LED's D1-D9?

Regards,

Jim 

Jim，

Thank you very much for your reply.
As you said, I've changed the power current.
If I press down the SW6（CPU_RESET）of TSW1400 EVM at the same time when update the firmware,These LED will be lit up：D1、D2、D3、D4、D7、D8、D9.
If I click on the capture button, all these LED don't respond.
Is this the right way to download firmware？Because I didn't find the firmware for ADS4449， I just pressed down the SW6（CPU_RESET） of TSW1400 EVM at the same time when update the firmware，and the software panel of HSDC had no error dialog box.

Guoming,

What version of HSDC Pro are you using? What revision is the TSW1400EVM? You should not have to hold down SW6. There may be an issue with the EVM. Can you try to download a DAC firmware without pressing this reset switch?

Regards,

Jim

Jim，

Thank you again  for your reply.

A good news ，The problem has been resolved. Both  TSW1400 and ADS4449 are working .

The cause of the problem is power supply. As you said Make sure the 5V power supply to the TSW1400EVM is capable of providing at least 4A.

But I still have to press down the SW6（CPU_RESET）of TSW1400 EVM at the same time when update the firmware. Although I haven't found the firmware for ADS4449.

Here's a picture I intercepted. There's a new problem. The amplitude of the pulse signal is 1V .The starting point of the pulse signal is 0V. Why is the capture starting at 6V?

Frequency of sampling & Pulsing signal  :

The version：TSW1400 REV D,ADS4449 REV E .

Guoming,

Did you modify the input stage of the board or is still connected to the transformer and AC caps? If you do a capture and look at the codes as a digital number instead of a voltage, this may help explain what you are seeing. Try sending a simple low frequency sinewave with a known amplitude and see how this correlates to the captured results.

Regards,

Jim

Jim

     I didn't modify the input stage of the board. I just connected the input  to the transformer and AC caps.

I captured the data again today,but the waveform still started at 6V. In addition, it attenuates to a fifth of the time.

Here's the chart.  The true input signal amplitude is 1 Vpp. start at: 0V. But the result of the capture is 0.2Vpp,and start at 6V. So why?

   

Guoming,

Using the ADC GUI, write to register 25h and set the ADC into digital ramp mode. Set the TSW1400EVM to do a capture and display in codes mode. You should now see a ramp. If you do not, the problem may be with the TSW1400 board. If you do see a uniform ramp, we can focus on the ADC board.

Regards,

Jim   

Jim

     I could see a uniform ramp ,as follows:

     a uniform ramp:

ALL  Zeros:

 So maybe there's something wrong with the ADC board?

Jim
I just measured the ADC board with an oscilloscope.
I found that the attenuation of the signal occurred on the ADC board.
For example:
If the amplitude of the input signal (output by signal generator) is 1V, the differential voltage after transformer and AC caps is just about 0.25V.
(I measured the voltage between R17 and R28 on the ADC board.)
This explains why the signal attenuated to a fifth of the time after ADC acquisition.
I still don't know why the signal started at 6V. I thought the common-mode voltage was incorrect.
The common-mode voltage which is 1.15V is very stable after the sampling frequency signal is given.

Can you tell me why there's a 6V bias?
Why the voltage after transformer and AC caps attenuated to a fifth of the time. Is the ratio of the transformer 1:1 ?


Best wishes

Jim

   AS you said in your letter.

   I  changed the Y-scale to codes on HSDC Pro when capturing data.

But the waveform I captured is still biased,As shown below.

The initial waveform is actually an amplitude of 1.4 V

 

The amplitude of the  initial waveform is actually 1.4 V from 0V.  Is something wrong with HSDC?

The problem haunted me for a long time, hoping to be solved as soon as possible.

In addition, ADS4449, according to the sample codes. how to calculate the original voltage?

        

     Good luck           

                                                                          Guoming Sun

    

Jim

       There's a new problem.

       When the input pulse amplitude exceeds 1 V, the waveforms displayed by HSDC Pro no longer increase in value.  As shown below：The first image is a Vpp=1.5V waveform，the peak is 7 V.

The second image is a Vpp=1.2V，but the peak is still 7V.   why？  

    The differential input  voltage is 1.15V . The allowable input voltage value of ADS4449 is -0.3V--1.9V，When the pulse amplitude is 1.5 V，The forward end of differential voltage is about  750mV+1.15V=1.9V（I Used THS4503 EVM to transform single end signal into differential signal，then connected to the differential input pin of the ADS4449）.

    So why the HSDC  Pro didn‘t  show a higher amplitude when the voltage of the pulse over  1 V ?

Guoming,

If you switch the Y-axis to codes, you will probably see that the ADC has reached it's max output value and is now in saturation. What is the P-P voltage across the analog input pins when this occurs? I am guessing it is above the max for the device. Since you are using the THS4503 EVM to convert your signal, I am guessing you are also getting some gain from this device which may be the reason for the saturation. What is the state of the over range pins? More info regarding these outputs can be found in section 8.3.1 of the data sheet. If the device is not in over range, then the issue is probably the common voltage on the input is not set properly.

Regards,

Jim 

Guoming,

Is it possible to send a oscilloscope screen shot with a differential scope probe connected across both inputs of this channel? Can you change the input to simple 1MHz sinewave and send me the HSDC Pro screen shot?

Regards,

Jim