Usage Notes and Known Design Exceptions to Functional Specifications
40
SPRZ412K – December 2013 – Revised February 2020
Copyright © 2013–2020, Texas Instruments Incorporated
TMS320F2837xD Dual-Core MCUs Silicon Revisions C, B, A, 0
Advisory
GPIO: GPIO0–GPIO7, GPIO46, GPIO47 Shunt to V
SS
Due to Fast Transients at High
Temperature
Revision(s) Affected
0, A
Details
There is a potential temporary internal shunt to V
SS
condition identified on pins GPIO0,
GPIO1, GPIO2, GPIO3, GPIO4, GPIO5, GPIO6, GPIO7, GPIO46, and GPIO47. In this
condition, an on-chip path to V
SS
is turned on, which can bring down the logic level of
these pins below V
IL
and V
OL
. The condition can occur when the pin is in input or output
mode and with any of the alternate functions muxed on to this pin.
The condition is more likely to occur at high temperatures and has not been observed
below 85°C under normal operating use cases. The triggering event is dependent on
board design and the speed of signals switching on these pins, with fast-switching
transients more likely to induce the condition. The condition has only been observed
when the signal at the device pin has a rise time or fall time faster than 2 ns (measured
10% to 90% of V
DDIO
).
The condition will resolve upon toggle of the IO at a lower temperature.
Workaround(s)
Try one of these two options:
•
Option 1:
Avoid the use of these pins in the revisions affected.
•
Option 2:
This condition is not seen on all products. Many PCB designs have enough
capacitance and slow enough edge rates that the condition does not occur. If the
application can be tested and functions correctly with the temperature margin above
the end-use temperature, then no action may be required. If the issue is seen or
additional margin is desired, then the following can be applied.
Place a capacitor of 56 pF or greater between each of these pins and ground, placed
as closely as possible to the device. This will slow down the fast transient seen by
the device and avoid triggering the condition. Larger capacitors will be more effective
at filtering the transient but must be balanced against the PCB level timing
requirements of these pins.
