DM8168 DDR3 controller specification

Subhranil Choudhury77614

In DM8168 the DDR controller clock is (SYSCLK8)/2 = 400MHz. But, it is specified in the datasheet that DDR3 interface clock is 800MHz. Can anybody clarify what is the interface clock at which DDR3 runs? Is it 400MHz or 800MHz? And if it is 800MHz how is this clock derived?

Does anyone has the DM8168 DDR3 controller datasheet? If yes, can you please share it?

over 14 years ago

0 MarcPyne over 14 years ago

TI__Mastermind 25055 points

Hello,

We are correcting this in the datasheet. SYSCLK8 is the DMM, DDR2/3 OCP clock (internal clock) and the max value supported is 400 MHz. The DDR3 external clock can run at up to 800MHz and it is tapped out directly from VCO (see DDR PLL section in the device TRM.)

Regards,
Marc

0 Andrew Dyer over 12 years ago in reply to MarcPyne

Intellectual 650 points

In the process of trying to figure out some custom clock settings I have been looking at SYSCLK8. I did a pdf search of the datasheet and TRM (SPRS614D, SPRUGX8B respectively) for SYSCLK8:

Table 7-15 in the Datasheet says SYSCLK8 has a max of 380 MHz for a standard speed part, 400MHz for -2 and -4
Table 7-16 in the Datasheet says SYSCLK8 is max of 400 MHz
Table 1-73 in the TRM says SYSCLK8 is 380 MHz and then later in the same table has it at 800 MHz
Table 1-74 in the TRM says 333 to 533 MHz for DDR2 and 333 to 800 MHz for DDR3
section 1.10.3.1.2 TRM says 400 MHz
Table 1-79 in the TRM says 380 MHz for the DMM and later in the same table 400MHz for the DDR2/3
Table 1-80 in the TRM says 398.25MHz
section 1.16.1.2.20 TRM says default is to run at 398.25 MHz
Table 18-21 in the TRM says 800 MHz

Processors

Processors forum

DM8168 DDR3 controller specification