Usage Notes and Known Design Exceptions to Functional Specifications
3.1.7
OSC1: RTC_XTALIN Terminal Has an Internal Pull-up Resistor When OSC1 is Disabled
The RTC_XTALIN terminal has an internal pull-up resistor that is turned on when OSC1 is disabled. OSC1
is disabled by default after power is applied.
This internal pull-up resistor was not properly documented in data sheet revisions D and earlier. These
early data sheet revisions recommended an external pull-down resistor to be connected to the
RTC_XTALIN terminal if OSC1 was not used. The recommendation should have been to leave this
terminal open-circuit when not using OSC1.
Connecting an external pull-down to the RTC_XTALIN terminal may cause unexpected leakage current.
The current recommendation is to remove any external pull-down resistor from the RTC_XTALIN terminal
and leave this terminal open-circuit when not using OSC1.
11
SPRZ360F – October 2011 – Revised November 2013
Sitara™ AM335x ARM
®
Cortex™-A8 Microprocessors (MPUs) (Silicon
Revision 2.1, 2.0, 1.0)
Copyright © 2011–2013, Texas Instruments Incorporated