• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 20 subscribers
  • Views 260 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMK03328: Figure 85. Recommendations for Power Up From Single-Supply Rail

Hirotaka Matsumoto
Guru 27525 points
Part Number: LMK03328

Hi all

Would you mind if we ask LMK03328?

There is the description,
"As shown in Figure 85, the PDN pin can be left floating, pulled up externally to VDD,
 or otherwise driven by a host controller for meeting the clock sequencing requirements in the system."


The PDN pin can be left floating and pulled up externally to VDD.
So, which is the recommendation between floating and pulled up for stability?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 18070 points

    Hi Hirotaka-san,

    If you're using single supply, i.e., all power pins ramp up at the same speed, then you can leave the pin floating.

    However, if the supply pins ramp up at different speeds, then you may need to slow down the PDN pin ramping by adding a capacitor to ground. You can still use 200kOhm internal pull up and choose a smaller capacitor, or use external pullup. This really just affects the ramping speed of this pin - it decides the current flow with which the capacitor is being charged.

    Regards,
    Hao