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AM3352: OSC1 connection recommendation

DJ-NG
Genius 9355 points
Part Number: AM3352

Hi champs,

referring to AM335x erratum (sect. 3.1.17) and DS (Section 6.2.2.5), unused OSC1_IN/OUT pins should be left unconnected.

Customer now has some older AM335x designs in the market, where OSC1_IN (with internal pull-up)/_OUT is hard connected to GND/VSS:

Q1: Can this cause functional problems ?

Q2: Can this cause any silicon defects mid/long term ?

Customer has to decide if a redesign is neccessary!

  • 0
    TI__Guru**** 393215 points
    Hi,

    Is VDDS_RTC power rail supplied?
  • 0 in reply to Biser Gatchev-XID
    TI__Guru**** 393215 points
    To answer your questions:

    Pin RTC_XTALIN: An internal 10 kohm pullup is turned on when the oscillator is diasabled. The oscillator is disabled by default after power is applied. If the pin is connected to GND this will cause approx. 180uA leakage from VDDS_RTC.

    Pin RTC_XTALOUT: This terminal is high-Z when the oscillator is disabled. This terminal is driven high if RTC_XTALIN is less than VIL, driven low if RTC_XTALIN is greater than VIH, and driven to a unknown value if RTC_XTALIN is between VIL and VIH when the oscillator is enabled. The oscillator is disabled by default after power is applied.

    To summarize, the way they have connected the pins will cause only leakage from the 1.8V VDDS_RTC rail if they don't enable the oscillator. However if the oscillator is inadvertently turned on the device may be damaged. In my opinion they should plan to redesign for future production.