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LM76003: spec discrepancies

Viktorija Cecil
Mastermind 18501 points
Part Number: LM76003


Team, 

Please help address customer's questions:

  1. On the LM76003, there is a note that the SYNC/MODE pin can be connected to either Ground (DCM/PFM mode) or “Logic High” (force FPWM mode).  What is the proper connection for “Logic High”?  Is this just routed back to the output voltage of the LM76003?
  2. The CBIAS cap is connected with pin 9 BIAS. Its value is 0.1uF in evaluation board. But the value is recommended 1uF in LM76003’s data sheet page 4. Which one is correct?
  3. The value of decoupling CAP is used 0.47uF for input pins PVIN  in evaluation board.  But the value is  recommended 47nF in LM76003’s data sheet page 27. Which one is correct?

Thanks

Viktorija

  • 0
    TI__Mastermind 35210 points
    Hi Viktorija,

    1. Logic high should be greater than 2V (See 6.7 Switching Characteristics-V_sync_low). What you could do is hook it right up to VCC. Keep in mind that the abs max for sync is 5.5V, which is the abs max for VCC. It sounds like the application might require a higher VOUT than the abs max if an external bias is being considered?
    2. A 1uF, ceramic cap with an appropriate DC rating will work.
    3. A 0.47uF high-frequency input cap, in addition to two 4.7uF caps will be sufficient. I would recommend choosing an X7R with an appropriate DC rating for the max operating input voltage.
  • 0 in reply to Marshall_Beck
    Prodigy 85 points

    Hi Marshall,

    Regarding response #1, the pin function description for VCC (datasheet Page 4) states that it is not recommended to load this pin with external circuitry.  Is it acceptable to tie SYNC/MODE to VCC?  Alternatively, could this be tied to the output voltage of the regulator?

    Regards,

    Bryan DeMaster

  • 0 in reply to Bryan DeMaster
    TI__Mastermind 35210 points
    Hi Bryan,

    The sync/mode pin will only pull a few microamps from VCC, so tying it to sync/mode should not be a problem.
    Also, tying sync/mode to VOUT should not be a problem either, assuming your output voltage is below the absMax for sync/mode .