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Question about using LTM4678 & LTM4675


My customer use LTM4678 & LTM4675 in same design.

So they ask about  the connection of SYNC pin and Share CLK pin between LTM4678 & LTM4675.

Q1) Can they connect  SYNC pin in LTM4678 and SYNC pin in LTM4675?

Q2) Can they connect  SHARE CLK pin in LTM4678 and  SHARE CLK in LTM4675?

Q3) Would you suggest any advices about the connection between LTM4686 and LTM4675 if they use in same design and with power sequencing?

Please advise me.



  • Hi Se-woong,

    A1) Yes, if they want to synchronize the clock signal of the LTM4678 to the LTM4675 or vice versa, they can connect the SYNC pins together. The FSWPHCFG pin of the secondary module needs to be set to External or Sync Slave in order to synchronize to an external clock (see Table 3 on page 31 of the LTM4678 datasheet and Table 4 on page 46 of the LTM4675 datasheet). 

    A2) Yes, they can connect the SHARE_CLK pins of the LTM4678 and LTM4675. SHARE_CLK is used to synchronize the time base between any ADI devices with a SHARE_CLK pin.

    A3) Connecting the SHARE_CLK pins together will help rail sequencing and rail tracking. The FSWPHCFG pins can be used to set the primary module's frequency, and it will also be used to set the secondary SYNC pin to External or Sync Slave. You can also use the FSWPHCFG pins to set the channel phase-interleaving angle when using multiple phases.