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C6457 DDRII PTV18 pin connection, documentation conflict

Bryan Busacco
Expert 1215 points

Please verify connection for PTV18.   Two TI documents may indicate a different connection.

See SPRAAG6D DDR2 Implementation Guide (Rev: Jan 2010) page 4 section 3.4,  "PTV-Compensated Output Impedance," mentions the C6457, but does not specify exactly what to do, yet clearly states what to do with the TCI6488 ( presumably the same IC ).

See SPRS582B Data Manual pg. 45 which says to connect to GND through a 47Ω, 5% resistor.

For the C6457 please indicate which is correct.

Thank you, Bryan Busacco

 

  • 0
    TI__Genius 12065 points

    Hi Bryan,

    First of all, C6457 should be comparable to TCL6484 instead of TCL6488.

    So in SPRAAG6D, it is saying PTV18 is connected to GND through a 45.3Ω, 1% resistor for TCL6484; in SPRS582B, it is saying PTV18 is connected to GND through a 47Ω, 5% resistor for C6457. Those two are very similar. 

    You can refer to either C6457 or TCL6484 document for the DDR implementation. Hope it works for you.

     

    Sincerely,

    Steven