USB regulator no 3.3v comes out from VOUT33

[danielchai]

Hi,

I am testing the USB device function on our board which uses MK60FN1M0VLQ12.

The connection is

USB 2.0                MCU(has independent power supply)

VCC------------------ VREGIN

D+  ------------------  USB0_DP

D-   ------------------- USB0_DM

GND ----------------  GND

                          VOUT33(floating)

Now I measure the VREGIN, it is 5v. But when I measure the VOUT33, it is about 0.3V.

Any ideas about this?

Thank you.

-Daniel

[dereksnell · Accepted solution]

Hi Daniel,

Is it possible the USB regulator was damaged on that device?  Is this issue happening on more than one board?  The USB signals are exposed to transients, and should be properly protected.  Transients on the VREGIN in pin can damage the USB regulator.  Here are some other links discussing that issue, and some protection options for the USB signals.

Taking the Kinetis L FRDM board to the next level, a real product

Re: Burnt two MK60FN1M0VLQ12 when plug in USB port

[danielchai]

Hi Derek,

I think the USB regulator is broken on the older two boards. Now I just solder a new board and add a 500ohm resistor between 5v and VREGIN. Then I measured the voltage output from VOUT33, it is 3.3v. The only differences is I add a 500ohm resistor between 5v and VREGIN.

I don't know if it is the reason causing the USB regulator damaged. But it seems it is very easy to break it.

Thank you.

[danielchai]

Hi Derek,

I am not sure.

I tested it on tow boards.

On the first board, after I connect the 5V to VREGIN, I measure the voltage on the VREGIN pin, it is 0.3v to 0.5v. It seems on this board, the USB regulator is damaged. 

On the second board, after I connect the 5v to VREGIN, I measured the voltage on the VREGIN, it is 4.98v, but the VOUT33 is about 0.1v.

I will try to make another board and add the protection circuit and check if it works.

Thank you.

-Daniel

[Paul_Tian]

Hi, Daniel

Do you add bypass capacitor(about 0.1uF) to pin VOUT33? If not,please add then continue your testing.

Hope my reply can help you.

Best Regards

Paul

[danielchai]

Hi Paul,

Now I use another new board and USB regulator part works.

The PC can detect the USB device, but it shows "Unknown devide". I installed the driver from C:\Freescale\Freescale_MQX_4_0\usb\device\examples\cdc\virtual_com\inf.

But it shows me:

Any ideas about this?

Thank you.

-Daniel

[danielchai]

Hi Paul,

I added a capacitor to the pin VOUT33, but the output is still 0.1v.

Is there any way that I can check to make sure the USB regulator is broken?

Thank you.

-Daniel