am335x DDR3 clock - Can I use 400MHz?

anil kolli

Other Parts Discussed in Thread: AM3352Hi TI, We are using AM335x in our design. I am following link http://www.ti.com/lit/ds/symlink/am3352.pdf I am confused about DDR3 clock, 1. in the first page It is mentioned that DDR3L supports 400MHz clock. 2. In the same document, under section 5.6.2.3 DDR3 and DDR3L Routing Guidelines it is written that , (1) The JEDEC JESD79-3F Standard defines the maximum clock period of 3.3 ns for all standard-speed bin DDR3 and DDR3L memory devices. Therefore, all standard-speed bin DDR3 and DDR3L memory devices are required to operate at 303 MHz. In beaglebone black sources I understood DDR3 is configured for 400MHz. Can I configure 400MHz DDR3 clock on AM335x? Regards & Thanks , Anil.

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Anil,

Yes, you can configure DDR3 for 400MHz. 303MHz is the minimum supported frequency for DDR3.

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

Prodigy 205 points

I am confused about the maximum clock rate for DDR3 for the AM335x.

This thread is talking about 400Mhz, however in the spruh73h.pdf section 7.3.2.2

it states that the maximum m_clk rate is 152Mhz (m_clk is defined as DDR_PLL_CLKOUT/2)

doesn't that imply that the maximum clock rate for DDR3 from the AM335x is 304Mhz (probably really 303Mhz)

(or is the can the DDR_PLL_CLKOUT be scaled before it becomes the DDR3 clock ?)

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

TI__Guru**** 393215 points

For DDR3 the maximum AM335X clock frequency is 400MHz and the minimum is 303MHz. See Table 5-56 in the AM335X Datasheet, Rev.F, and sections 7.3.3.2 and 8.1.6.3 in the AM335X TRM, Rev.H.