Part Number: CDCE6214-Q1
I have the HW_SW_CTRL pin pulled high on power up and a 25MHz crystal connected. The OE control is also pulled high. However I'm not getting anything on the outputs. The supply voltages are nominal at 1.8V. What should I look for to debug?
Thanks and Regards,
Please first check and see if REFSEL is pulled low. This makes sure that it selects SECREF (XTAL) as reference. If you have I2C connected, read back bit R7 LOCK_DET to see if PLL is locked.
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In reply to Hao Z:
I have REFSEL tied low with 4.7K on the schematic. I'll verify in the lab tomorrow.
I will hook up the USB2ANY and work to readback the Lock info.
In reply to Lee Sledjeski:
Understood. Please let me know when you have the results.
I'll temporarily close this thread since it's been open for a few days. You can still reply to it when you have the results.
Finally back to this ... I downloaded the TICSPRO software
R7 = 0 which indicates the PLL is unlocked.
I noticed my PDN connection is direct to VDD (via a 0 Ohm resistor) without any series resistance.
If I probe the 25MHz crystal what amplitude would you expect?
Anything else I should look for?
The voltage amplitude of the crystal cannot be predicted and we typically measure the current flowing through the crystal. For details, please look at this appnote: https://www.ti.com/lit/an/snaa331/snaa331.pdf?ts=1595820920482&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FCDCE6214-Q1
Regardless, the PDN pin cannot be tied to VDD directly. You can use external 4.7k pull up and 0.47uF cap to ground in order to slow down the PDN pin ramping. Alternatively, just float PDN pin because it has 50kOhm internal pullup.
Thanks Hao. Will update the PDN connection and see if that allows the part to start up.
No problem. Let me know.
Adding a capacitor to GND is not changing the CDCE6214 power up response. Is there something I can do to reload or program settings for 100MHz outputs?
Did you also remove or replace the 0Ohm resistor between VDD and PDN pin?
Yes you can use Ticspro to program the device. You can start with default configurations (in the tool bar) for sanity check.
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