Can CLKOUT1 be used in AM335x to generate 24MHz clock for external USB hub?

John J Wu

Hi,

Can CLKOUT1 be used in AM335x to generate 24MHz clock for external USB hub? USB hub controller is USB2514. The clock input to AM335x is a 24MHz crystal.

I looked up the TRM for AM335x, but I could not find the jitter performance for CLKOUTx.

Thanks,
John

over 13 years ago

0 Biser Gatchev-XID over 13 years ago

TI__Guru**** 393215 points

Hi John,

According to section 4.2.3 of the AM335X datasheet "The CLKOUT1 signal is always a replica of the OSC0 input clock which is referred to as the master oscillator (CLK_M_OSC) in the AM335x ARM Cortex-A8 Microprocessors (MPUs) Technical Reference Manual" (Figure 8-14). So its jitter should be equival to the 24MHz crystal oscillator jitter.

Best Regards

Biser

0 John J Wu over 13 years ago in reply to Biser Gatchev-XID

Genius 3870 points

Thanks a lot Biser!

0 Abhiram Balasubramanian over 12 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

Hi Biser,

I am using CLKOUT1 output for audio MCLK and my master oscillator is 24 MHz. As the TRM (AM335x technical reference manual) says, the master oscillator is same as CLKOUT1, I would like to know if there is a possibility of dividing the CLKOUT1 internally before feeding to audio MCLK? Thanks in advance.

Regards,

0 peaves over 12 years ago in reply to Abhiram Balasubramanian

TI__Guru 63145 points

The CLKOUT1 source does not have an internal divider option. See Section 8.1.6.12, CLKOUT Signals, in the TRM.

Also read Section 4.2.4, Output Clock Characteristics, in the Data Sheet before deciding to use the CLKOUT1 signal.

Regards,
Paul

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Can CLKOUT1 be used in AM335x to generate 24MHz clock for external USB hub?