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 (> 1kΩ)
- 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. Provide provision for
series resistor to control the fall time
Schematic Review
Follow the below list for the custom
schematic design:
- Verify the pullup resistor
values used
- Pullup referenced to the processor VDDSHVx or
VDDSx (I2C pullup connected to correct voltage)
- Addition of series resistor for fall time
control
- Fail-safe interface (emulated
IOs are not fail-safe, no input can be applied before the processor supply
ramps)
- Processor VDDSHVx or VDDSx and the attached
device IO supply sourced from the same supply
- Supply rails connected follow
the ROC
Additional
- Verify fail-safe
operation when connected to external interface signals.
Applying an external input before supply ramps can cause
voltage feed and can affect the custom board functions
- Review the Timing and switching characteristics, I2C
Exceptions section of the data sheet during the
design stage
- I2C controllers are multiplexed with standard
LVCMOS IO to emulate open-drain