LMK04828BEVM: PLL1 LD doesn't blink

Hiroaki Kawamoto

Part Number: LMK04828BEVM
Other Parts Discussed in Thread: USB2ANY, LMK04828

I'm testing LMK04828BEVM board.

I set the default settings for 122.88MHz reference clock, and input 1.5Vpp 122.88MHz clock to CLKin1.

PLL2 is locked and PLL2_LD is blinking, but PLL1 is not.

The green LED on USB2ANY is blinking.

Is there any suggestion to fix it?

0 Noel Fung over 1 year ago

Hi Kawamoto-san,

First of all, check the USB2ANY.

After connecting USB2ANY to the PC, do you see red or green Connection Mode?

It should be green when you plug in the USB2ANY to a PC.

Next, go to USB communications and then Interface.

If you get green light in below, click the Identify button, the LED on the USB2ANY will blink a few time then stay ON. USB2ANY is ready.

0 Hiroaki Kawamoto over 1 year ago in reply to Noel Fung

Yes, the connection is fine.

I can see green connection mode, and read/write registers normally.

0 Noel Fung over 1 year ago in reply to Hiroaki Kawamoto

Hi Kawamoto-san,

Great, if you confirm register read/write is no problem that is great.

Next step, check the Vc pin signal of the VCXO with a scope. If PLL1 is locked, Vc voltage should be around 1.65V.

0 Hiroaki Kawamoto over 1 year ago in reply to Noel Fung

Do you mean VCC_VCXO(U2 on the board, CVHD-950-122.88) voltage?

It is around 3.3V on VCC_VCXO_TP as specified in the datasheet.

0 Hiroaki Kawamoto over 1 year ago in reply to Hiroaki Kawamoto

It is also around 3.3V on Vcc1_VCO on LMK04828.

0 Noel Fung over 1 year ago in reply to Hiroaki Kawamoto

Hi Kawamoto-san,

Please check pin 1 of CVHD-950 with a scope.

Clock & timing forum