ADAU 1701 powering
Hi,
I have a programmed adau 1701 evaluation board, and it works fine when I use the USBi as the power supply. However, when I unplug the USBi and remove the jumper, powering the evaluation board by a 5V DC power source, it failed to function; it continuously output white noise, I have already have a EEProm to have the chip to read from every time I reboot it, and therefore the chip does have a program in it when a 5 5V DC power supply is connected. I'm wondering if it needs a power circuit to run the chip. or I need to feed it with a start signal.
Can anyone please help me?
Regards,
Joseph
I experienced that when a power supply takes time to come up (because of capacitors) the ADAU fails to start properly.
Hello Joseph,
I think I know what is going on. We had to change the company that builds these boards for us and in the process they made an error entering the BOM into their system. R6 was entered as a 78.7 ohm resistor instead of a 78.7K ohm resistor! Slight difference. This resistor is part of the divider to set the voltage of the 3.3V regulator. When running off of USB the voltage is still in the range where it works OK but when you switch to the barrel jack it stops working. So check R6 to see what the value is. R6 is located near LED D3 and also near the DC power jack.
Here is a post where we first discovered this error.
https://ez.analog.com/dsp/sigmadsp/f/q-a/101002/powering-adau1701-miniz/300895#300895
Let me know if you need more help. Hopefully you have some SMT rework tools. It is not too difficult.
The error was only in the first small batch of boards and I requested they recall them but that might not have happened or yours slipped through the cracks. The error has been fixed.
Dave T
Please log in to reply.