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TPS61178: tSTARTUP, tPRE_CHARG, TON_PFET

Takashi Yamaguchi
Genius 13380 points
Part Number: TPS61178

Hi team,

My customer wants to know about the startup timing of the tSTARTUP, tPRE_CHARG, TON_PFET.

Where  do the tSTARTUP, tPRE_CHARG, TON_PFET correspond in the Fig.27? Please see the example below.

/cfs-file/__key/communityserver-discussions-components-files/196/TPS61178.ppt

Regards,

Yamaguchi

  • 0
    TI__Mastermind 46905 points
    the Ton_PFET is mainly depend on the capacitor in parallel with the P-FET gate and source. it is period that Vgs of the P-FET from zero to threshold voltage.
    the tPRE_CHARGE is 2.6ms
    The tSTARTUP is 3.2ms if the reference voltage ramps up from zero. however, after the tPRE_CHARGE, the reference voltage is charged by the FB voltage. so the real startup time is (1.2-VFB)/1.2*3.2ms. the VFB is the voltage after the pre-charge finish.