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Original question:

TMS320C6652: DDR unused- Clock recommendation

TMS320C6652: DDR unused- Clock

Divy
Intellectual 380 points
Part Number: TMS320C6652

Hi,

From the keystone Hardware guide, it is mentioned that unused LVDS clock can be terminated.

So is that the same case with DDRCLK ? I am not using DDR for processor .

Datasheet Pg 73 Power sequencing shows the DDRCLK . Does the DDRCLK required for intial boot up or it can be left terminated as per LVDS unused recommendation?

Please clarify

Regards,

Divy

  • 0
    TI__Mastermind 46460 points

    Divy,

    Please see notes under '6.3.1 Power-Supply Sequencing' of the C6654/2 Data Manual:

    The clock input buffers for CORECLK, DDRCLK, SGMIICLK (C6654 only), and PCIECLK (C6654 only) use only CVDD as a supply voltage. These clock inputs are not fail-safe and must be held in a highimpedance state until CVDD is at a valid voltage level. Driving these clock inputs high before CVDD is valid could cause damage to the device. Once CVDD is valid it is acceptable that the P and N legs of these CLKs may be held in a static state (either high and low or low and high) until a valid clock frequency is needed at that input. To avoid internal oscillation the clock inputs should be removed from the high impedance state shortly after CVDD is present.

    Tom

  • 0 in reply to Tom Johnson 16214
    TI__Mastermind 46460 points

    Divy,

    However, note that there is a known issue with this device when you are operating without DDR.  You still need to provide a clock to the DDR to allow the logic to properly initialize.  Otherwise the DDR controller and PHY logic will draw more power than expected.

    Tom