General
Review and verify the following for
the custom schematic design:
- Above section including
relevant application notes and FAQ links
- Pin attributes and signal
description
- I2C interface configuration
and recommended connections (including IOSET)
- Electrical characteristics,
timing parameters and any additional available information including
exceptions
- Attached device address pin
connected to IO supply through a resistor (>1 kΩ)
- A pullup is recommended when
IO is configured as I2C interface
- Note the I2C exceptions in
the timing and switching characteristics section of the processor-specific
data sheet
Schematic Review
Follow the below list for the custom
schematic design:
- I2C controllers are
multiplexed with standard LVCMOS IO, connected to emulate open-drain
- Verify the pullup resistor
values used
- Pullup referenced to the
processor IO supply group VDDSHVx (I2C pullup connected to correct
voltage)
- Addition of series resistor
(low pass filter) for fall time control
- Fail-safe interface (emulated
IOs are not fail-safe, no input can be applied before the processor supply
ramps)
- Processor IO supply group
VDDSHVx and the attached device IO sourced from the same supply
- Supply rails connected follow
the ROC
Additional
- Verify fail-safe operation when
connected to external signals. Applying an external input before supply ramps
can cause voltage feed and affect the processor performance
- Review the Timing and
switching characteristics, I2C Exceptions section of the data
sheet during the design stage