Excessive oscillator output voltage to pextal pin, Fixed – Intel DBPXA250 User Manual
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DBPXA250 and DBPXA210 Development Platforms Specification Update
Intel
®
DCPXA250 Processor Card
8.
Excessive Oscillator Output Voltage to PEXTAL Pin
Problem:
On systems using an oscillator to drive PEXTAL, the 3.3 V output from the oscillator is too high.
Implication:
Possible damage to chip.
Workaround:
Follow the steps below:
Note:
These steps bring the oscillator voltage down to 1.1 V. The oscillator and core voltages need to be
equal.
1. Attach one side of a 430-ohm resistor to the bottom (on the bottom of the processor card) of
TP19 (ground).
2. Attach a 30-AWG wire from the remaining side of the 430-ohm to crystal X1 (The pin closest
to the edge of the board).
3. Attach one side of a 620-ohm resistor to the junction of the wire and the 430-ohm resistor. The
two resistors will “sandwich” the wire going to X1.
4. Attach another 30-AWG wire from the +3.3 V oscillator output (bottom of U7) to the open end
of the 620-ohm resistor.
Status:
Fixed
Board Rev:
Rev C
Figure 9. Voltage Divider
Figure 10. Close-up of Voltage Divider