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PMP9766: PMP9766 issue

Big Bill
Expert 1980 points
Part Number: PMP9766
Other Parts Discussed in Thread: TPS63020,

Dear All:

    I read the   in the 3.2   Backup Capacitor Charging Operation  the file describe“ First, the converter must be in forced PWM mode. The converter is able to operate in the reverse direction only in this mode. To enable the forced PWM mode, the PS/SYNC pin must be programmed to a logic high level. The TPS63020 data sheet (SLVS916C) shows a detailed description of this mode pin. Secondly, the output voltage of the TPS63020 must be programmed to a lower value than the system voltage” I want to know if the PS PS/SYNC pin must be programmed to a logic high level, if the super-capacitor  reach the 1.8V level, the IC to boost function, that the system can't charge the super-capacitor. Can you tell me how to charging  Operation？

  • 0
    TI__Expert 7925 points

    Hi Bill,

    If I understand correctly, you want to know how does charging/discharging of the supercap works? 

    The supercap is first pre-charged via diode, as shown in Figure 5 of PMP9766 (showed as "pre-charging operation" interval). When the supercap voltage reaches 1.8 V (minimum input voltage required for turn-on) then the converter turns on and charges the supercap (showed as "charging operation" interval). The PS/SYNC pin must be high, because reverse operation is only possible in forced-PWM mode. When the supercap is charged to 5 V, the converter is switched to power-save mode and the charging is stopped. 

    When the main power goes down, the converter is switched to forced-PWM mode and it starts discharging the supercap. When the supercap is discharged down to 1.5 V (undervoltage lockout threshold), the converter shuts down.

    Best regards,
    Milos 

  • 0
    TI__Expert 7925 points

    Hi Bill,

    We haven’t heard back so we're assuming this answers your question. If not, just post a reply below, or create a new thread if the thread has locked due to time-out.

    Thanks and regards,
    Milos