MKL26Z64VFM4 Power connections?....need guidance

[jwyoungster]

The MKL26Z64VFM4....Power:

Vdd to 3.3V

Vss to GND

VddA I tie to the same 3.3V that Vdd is connected to

VssA I tie to GND

 I have a seperate 3.3V supply that creates my 3.3V..this 3.3V powers the Vdd of the MKL as well as other parts/devices on in the circuit....this is why I do not use the VOUT33 to power anything...

Question:  DO I have to power VREG pin for the USB power internally to work?....(i..e put 5V into VREG, which then powers the USB internal 3.3V regualtor)?

Question: is VOUT33 the internal USB 3.3V regulator brought to the outside, or a DIFFERENT regualtor?

Right now, in my circuit, i have nothing tied to VREG.  I have my speperate 3.3V power supply tied to MLK Vdd and VOUT33....Q:  is this correct? or do I need to do something differnet?...

The reason I ask...USB is not recognized when I run the system...

see the schemo attached.

again, I dont want to power the entire board with the VOUT33...I see some "teensy LC " parts that use this to power the board as they only have two parts on the board......

the datasheet needs some serious updates to highlight what is going on inside this chip.....imho

jwyoungster@verizon.net

[nxf63973]

Hi Jhon Young

I apologize for the delay in my response.

The pin Vreg is the input of the internal USB Voltage Regulator. The output of this regulator supplies power to the USB transceiver,  so it is necessary to power Vreg to use the USB.

The USB Voltage Regulator also powers the pin Vout33.  Some designs use this output to power the MCU.

You can see more information about this in Chapter 3.9 Communication interfaces and Chapter 36 USB Voltage Regulator of the KL26 Sub-Family Reference Manual.

Also, I would recommend you to see Chapter 9.6 Hardware Implementation of the USB module in the document  Kinetis L Peripheral Module Quick Reference.

Please let me know if you need any more information.

Regards

Jose