AM4376: CLKOUT1 specification

user576134

Prodigy 110 points

Part Number: AM4376

I know the questions were already asked. But the answer doesn’t help.

In sections 5.13.2.4 is written “See the device-specific TRM for more details.” But where is the TRM?

I want to know details about output clock jitter.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

You will find it in the AM4376 product page: www.ti.com/.../technicaldocuments Under "User guides" there is a link to "AM437x Sitara Processors Technical Reference Manual (Rev. G)": www.ti.com/.../spruhl7g.pdf

0 user576134 over 8 years ago in reply to Biser Gatchev-XID

Prodigy 110 points

I already found this page and your document, but I don't find there information about the output clock jitter. The Technical Reference Manual (Rev. G)": www.ti.com/.../spruhl7g.pdf is for AM437x and not a device-specific isn't it?

0 Biser Gatchev-XID over 8 years ago in reply to user576134

TI__Guru**** 393215 points

Yes, the TRM covers the entire AM437x family. There are no jitter specs on CLKOUT signals of these devices. If you require a low-jitter external clock you should use the EXTDEV PLL (TRM section 6.6.12), which can be routed out on both CLKOUT pins (see Figure 6-17 in the TRM).

0 user576134 over 8 years ago in reply to Biser Gatchev-XID

Prodigy 110 points

I would like to use the CLKOUTs to supply two DP83822 Ethernet PHYs. This would save me the cost for two crystals.

Since you can’t give me the jitter details, can you tell me if the jitter of the AM437x is good enough for the XI Input of the PHY if I use the EXTDEV PLL?

0 Biser Gatchev-XID over 8 years ago in reply to user576134

TI__Guru**** 393215 points

Yes, please see Notes 1 and 2 below Table 5-10 on page 185 of the TRM:

(1) SYSBOOT[18] can be used to supply a clock for external ethernet PHY devices. If SYSBOOT[5]=0, EXTDEV_PLL will be configured to 25MHz, if SYSBOOT[5]=1, EXTDEV_PLL will be configured to 50MHz.
(2) The functionality provided by SYSBOOT[18] is only available in PG1.2 silicon.

0 user576134 over 8 years ago in reply to Biser Gatchev-XID

Prodigy 110 points

Ok, thank you.

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AM4376: CLKOUT1 specification