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TPS53679: About the correct design of the controller Vin pin

LienChieh
Prodigy 50 points
Part Number: TPS53679
Other Parts Discussed in Thread: TPS53622, TPS53659

Hi BU,

May I know that the controller Vin pin needs to be in front of the beads or after the beads if I add bead(input inductor) to design. Just like TPS53679, TPS53659, TPS53622.....

 

Jet

  • 0
    TI__Expert 5830 points
    Hi Jet,

    For the application which not requires input current sensing, it is suggested to connect pin11/12 together before bead/inductor(P12V).

    Thanks,
    Chasel
  • 0 in reply to Chasel Chen
    Prodigy 50 points
    Hi Chasel,

    So if connect after bead, what effect will it have?

    Jet
  • 0 in reply to LienChieh
    TI__Expert 5830 points

    Hi Jet,

    It should not make any difference as long as controller GND(thermal pad) connect to the system GND(most of time is layer 2) immediately thru GND vias(least impedance), and pin 11/12 are connected from input bulk cap directly (more stable VIN). The purposes we recommend to connect pin 11/12 to the plane before bead/inductor is to isolate the noise generate (high dv/dt on pstage Vin plane) to the controller. More noise inject on pin 11/12 may lead to higher jitter, however, it is very dependent to layout.
     
    Thanks.
    Chasel