About operation temperature of ADAU1446

Hello Seongjong,

All the production parts are tested at high temperatures so I know that it has been tested to 105 before it left the factory. The specification is the ambient air temperature so the junction temperature would be higher. So it does appear that you have a failure well below the rated specification. So, unless this happens to be a part that has become a defective part, I would look elsewhere for the problem and consider this a symptom. One way to rule out a part failure is to replace the part and see if a new part has the same issue.

You asked about the regulator. This is something to look into. The ADAU1446 will draw more current at high temperatures so that could be enough to cause a problem with the regulator. Plus, regulators are usually de-rated to a lower current at high temperatures so it is something to look into. Can you power the board with an external lab supply as a test? This way you can also monitor the current draw to see if it changes?

Are you controlling the volume control from a system controller using I2C or SPI? Are you using GPIO port and a pot to control volume? There is a possibility that the communications is a problem. Should there be a problem with the I2C bus this could cause the program to not load properly from a boot EEPROM and cause errors with volume control commands. Look carefully at the waveforms and voltage levels.

If you have an active probe you can look at the signal integrity of the communications clocks and data. When the temperature goes up then drive strengths change, capacitance change and this can cause the waveform reflections/ slew rate/ etc. to change. Then to make things worse the logic thresholds on parts will slightly change. This can cause errors at high temperatures that work, but are on the edge, at normal temperatures.

Signal integrity may be part of the problem since it looks like you have many digital devices that will need clocks. How you distribute the clocks will be important. Feel free to send me a private message if you wish to share more detailed product information.

Thanks,

Dave T

Hellow Mr. Thib

I appreciate your response.

Some trials you mentioned above, I already checked.

I monitored regulator output voltage if there is voltage drop due to insufficient current, but the voltage was not decreased. I also tried to supply power with lab power supplier, and the failure symptoms of high temperature were same.

Actually we ordered new part (ADAU1445) recently, because we think the exposed pad (as you know, ADAU1442 dose not have exposed pad) might be more helpful for high temp. issue. We tested ADAU1445 at high temperature, but the symptoms were same.

Regarding communication peripherals, we are using SPI to control the DSP. The SPI is shared with FPGA which is in the same board. Using chip select signal, we can select DSP or FPGA. At the high temperature, the FPGA is controlled well by SPI but DSP can't be contolled.

So, I still very much wondering why the DSP can't work at 85 cel. degree which is significantly lower than datasheet temperature.

Please let me know what I missed to check.

Thanks,

S. J. Lee

Hellow Mr. Thib,

Regarding SPI control, you mentioned GPIO port.

Now we are using SPI port (CLATCH, SCL/CCLK, SDA/COUT, and ADDR1/CDATA) of the DSP.

Can we cahnge SPI port to GPIO port? If so, can we get some proper DSP logic to use the port for SPI from Analog Device?

We checked all related voltage and clocks but there were no strange or abnormal things.

I am still very much wondering why the DSP is not controlled at high temp.

Thanks,

S. J. Lee

This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

Thank you,
EZ Admin