ADS6145 output data inversed

Hi,

The ADS614x family has a internal register for test pattern generation. The bit [D7:D5] of register address 0x0A is for test pattern. For all ones, you can set [D7:D5] as "010". Please refer to page 18 in datasheet.

The typical value of output buffer supply voltage for DRVDD is 1.8~3.3V. The maximum recommended load capacitance is 10pF. Do you provide 3.3V for DRVDD in your system?

Thanks,

KW

Yes. I have 3.3 V supply at J11.  I  think the default mode is double data rate LVDS, refer to page 2 in datasheet.   The data sheet says the default output is cmos parallel.  I hope any time I use this ads6145 could be very easy, by just plug in power and I/O pins.

Are you able to set D8 of register 0x00 as '0' for CMOS interface?

Thanks,

KW

Are you talking about change in 'TI ADC SPI Interface'?  It change be changed, but the software shows an error too.

It looks GUI driver issue. Would you try attached procedures to resolve this issue?

2570.EVM_WinXP.zip

And also you can download the latest version of GUI at the link below.

http://www.ti.com/tool/hsadc-spi-utility

Thanks,

KW

The new software still remain a problem.  If I send data from this GUI, it shouldn't have any wrong character such as ? or @. 

Can you send me the capture screen of device manager from control panel?

Thanks,

KW

Here is my device manager from control panel.  I don't see usb connection from ADS6145, but I have USB cable connected to the device.

Did you supply power with your EVM also? Just in case, can you please try unplugging "Intersil ISL5239 Eval Board" and check Device Manager window again?

Thanks,

KW

Here is the Device Manger window after I unplugged ISL5239.

I wonder if I move J5 '0 ohms' resister from short 1-2 to short 2-3 which is powered off. Will it solve the problem? 

The default selection for J5 is "1-2" which is power-on for ADS61xx device. I'll be working on this issue and update you. By the way, your OS looks Window 7. Have you logged in your PC as administrator? Something should come up at the device manager window but nothing showed up.

Thanks,

KW

To use SPI interface, please check below jumper settings along with 5V of power supply to J20 (this is for SPI).

J2, J3, J6, J7: 1-2

JP7: 2-3

with these settings, you'll see "TI ADC SPI Interface" and be able to control GUI. I'll pull off one EVM from our stock and duplicate this.

Thanks,

KW

Thank you. I get the software working now.

LVDS mode has Double rate data output which looks like the first two screen shots I posted,  but in CMOS mode, all output pins look like my 2nd screen shot which is inverted. Is there a way I can make the CMOS mode output look like my first screen shot?  

Hi, Zaidi

Sounds good to hear you are able to change any register value from EVM, I have a couple of more questions regarding your settings.

Have you tried internal test mode?

What is your clock frequency from external signal generator? what is the data format, offset binary or two's complement?

where is your analog input source coming from?

Thanks,

KW

Signal is from Agilent's  Arbitrary Waveform Generators.  It has 70 MHz  carrier frequency and 5 MHz bandwidth,  the clock frequency is 125MHz and it's two's complement.

I haven't tried internal test mode.

thanks

Zaidi

Hi,

Please find attached slides which show captured screen from TSW1400 GUI and ADS6145EVM. I used 10MHz single tone with 125MHz of sampling clock and this is LVDS interface. SNR is 71.09dB and SFDR is -93.52dBc. Everything looks good to me. ADS6145 has CMOS/LVDS options but ADS6145EVM is designed for LVDS only. I am not sure how you tested this EVM with CMOS mode.

In CMOS mode, the DRVDD current scales with the sampling frequency and the load capacitance on the output pins. Please refer to Figure 87 from datasheet.

8880.DAC6145EVM_TSW1400_Lab_Setup.ppt

Thanks,

KW

hello KW,

Thank you for solving the voltage level problem. 

The slide figures are very nice, but I don't have TSW1400.   This is one output pin from ADS6145 with CMOS binary offset.  My last problem is that how to make it inverted.  i have another board will trigger the signal base on the magnitude.

I think I know how this happened.  ADS6145 is counting voltage level, and my AWG signal includes positive and negative voltage.   ADC counted 0 voltage from the negative peak, and the input ground was counted as a higher voltage.  That's how ADC shows 'inverted' digital output.  Sorry for the confusion before.

Do you have any advise which help me handle this issue?

Green color is the MSB from ADS6145, purple is the input signal.

With CMOS & binary offset mode using all ones of internal patten, I was able to see the output bits tied high. 1st and 2nd screen shots you showed me looks like LVDS, which shows positive and negative values. Can you please try internal pattern to verify this?

Thanks,

KW

I don't know what is  internal pattern.  I got this ADC working now. 

Thank you for helping.

Zaidi