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TPS546D24A: Power-On Sequence

Shinichi Yokota
Genius 9715 points
Part Number: TPS546D24A

Hello,

Does TPS546D24A require a power-on sequence for PVIN, AVIN, VDD5, and EN pins? In my case, +3.3 V is supplied to the PVIN and the AVIN pins together, and +5 V is separately applied to the VDD5 pin. This supply connection is very similar to Figure 7-4 of the data sheet.

My sequence is, +3.3 V is first turned on, then +5 V goes up, and the EN pin is lastly enabled.

Best regards,
Shinichi Yokota

  • +1
    TI__Guru 52225 points

     

    Shinichi Yokota said:
    Does TPS546D24A require a power-on sequence for PVIN, AVIN, VDD5, and EN pins?

    The TPS546x24A is designed to support a very wide range of power-on sequencing among it's 3 supply and enable pins.

    EN/UVLO, AVIN, PVIN, and VDD5 power can be applied in any order.  The Output will not enable until all Power On requirements (PVIN > VIN_ON, AVIN > UVLO, VDD5 > UVLO_Switching, and EN/UVLO > ENthreshold.

    If an external 5V is provided to VDD5, it should be protected against being overloaded by other devices connected to the same 5V supply or reverse-bias loading of the 5V supply to its source supply if that source may be lower than the AVIN input voltage.

    Note:  If SYNC will be used to drive an external charge pump, such as illustrated in Powering the TPS546D24A Device Family From a Single 3.3-V Input Power Supply (Rev. A) (https://www.ti.com/lit/pdf/sluaa03) SYNC_CONFIG = SYNC_OUT should be selected with the programming of the ADRSEL pin as the SYNC pin does not generate an output in AUTODETECT until after conversion is enabled, and conversion will not be enabled until VDD5 is > 4V.

    Shinichi Yokota said:
    My sequence is, +3.3 V is first turned on, then +5 V goes up, and the EN pin is lastly enabled.

    This sequencing is ideal for the operation of the TPS546D24A, just ensure that any other devices connected to the 5V will not generate more than 100mA of loading on VDD5 when VDD5 = 3.3V.