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TPS546D24A: NVM Programming Time, etc.

Shinichi Yokota
Genius 9715 points
Part Number: TPS546D24A

Hello,

I have two questions about TPS546D24A.

  • The data sheet says in the Note of the section 7.5.2 Pin Strapping, "Allow a minimum 100 ms for the device to complete a burn of NVM User Store," but what's the maximum NVM programming time?
    • Or, does it mean that the NVM programming will complete in 100 ms and it'll be no issue if a user waits for at least 100 ms?
  • First, is it correct to understand that from the Table 7-14 of the data sheet there is no selection of the combination of "Auto Detect" for the "SYNC IN / SYNC OUT" and "32d – 47d" for the "SLAVE ADDRESS" range?
    • Second, if that's correct, which SYNC direction, "Sync in" or "Sync out," do you recommend for a stand-alone (single-phase) device?

Best regards,
Shinichi Yokota

  • 0
    TI__Mastermind 32370 points

    Hello, 

    a 100ms will guaranty the burn out. why do you need a max? After you wait for 100ms, then the device is guaranty NVM  burn, you can wait as much s you want after that. 

    I assigned this to Peter to answer the other questions 

    Thanks 

    Tahar

  • +1
    TI__Guru 56925 points

     

    As Tahar Allag mentions, 100ms is the maximum NVM clear and write timing.  If the user provides 100ms or longer for the NVM write, they will ensure a successful STORE.

    Shinichi Yokota said:
    First, is it correct to understand that from the Table 7-14 of the data sheet there is no selection of the combination of "Auto Detect" for the "SYNC IN / SYNC OUT" and "32d – 47d" for the "SLAVE ADDRESS" range?

    Yes, that is correct.  Auto Detect is only available with the single resistor to AGND programming of ADRSEL, which only allows for addresses of 10h - 1Fh (16d - 31d)

    Shinichi Yokota said:
    Second, if that's correct, which SYNC direction, "Sync in" or "Sync out," do you recommend for a stand-alone (single-phase) device?

    If SYNC will not be used on a single-phase application, TI would recommend that the converter be programmed for SYNC_IN and the SYNC_PIN be shorted to PGND at the exposed pad to limit noise generation and susceptibility.

    IF SYNC will be used, SYNC_IN or SYNC_OUT should be selected in accordance with how the SYNC pin will be used.

  • 0 in reply to Peter James Miller
    TI__Genius 9715 points

    Peter,

    Peter James Miller said:
    If SYNC will not be used on a single-phase application, TI would recommend that the converter be programmed for SYNC_IN and the SYNC_PIN be shorted to PGND at the exposed pad to limit noise generation and susceptibility.

    I found the description in the section 7.3.12 Frequency Synchronization on page 30 of the data sheet that says the switching frequency will be around 50% of the nominal in a stand-alone device. Is it correct?

    "When configured for SYNC_IN, if SYNC input pulses are missed for two cycles, or the oscillator frequency drops below 50% of the free-running switching frequency, the device determines that SYNC clock is lost...Single phase stand-alone devices continues to operate at approximately 50% of the nominal frequency."

    If the switching frequency is set to 1,500 kHz, the Max of the range, will the TPS546D24A operate at 750 kHz?

    Best regards,
    Shinichi Yokota

  • +1 in reply to Shinichi Yokota
    TI__Guru 56925 points

     

    Shinichi Yokota said:

    I found the description in the section 7.3.12 Frequency Synchronization on page 30 of the data sheet that says the switching frequency will be around 50% of the nominal in a stand-alone device. Is it correct?

    "When configured for SYNC_IN, if SYNC input pulses are missed for two cycles, or the oscillator frequency drops below 50% of the free-running switching frequency, the device determines that SYNC clock is lost...Single phase stand-alone devices continues to operate at approximately 50% of the nominal frequency."

    This is the description of how the TPS546D24A reacts to the loss of SYNC after SYNC has been established.  Until SYNC is established, the converter will run at the programmed free-running switching frequency.

    If a device is programmed for SYNC_IN and 1,500kHz, if there is no signal on SYNC, the converter will run at 1.5MHz.  If there is a 1.2 - 1.8MHz SYNC signal provided to the SYNC pin, the TPS546D24A will synchronize to that SYNC frequency.

    If the SYNC frequency drops below 750kHz, or is lost completely, the switching frequency will drop to 750kHz until SYNC is recovered and the TPS546D24A returns to the frequency of the external SYNC signal.