General
Review and verify the following for
the custom schematic design:
- Above sections, including
relevant application notes and FAQ links
- Pin attributes, signal
description, and electrical specifications
- Electrical characteristics,
timing parameters, and any additional available information
- Reset signal is asserted
(low) while the processor supplies are ramping up or down
- MCU_PORz POR input is 3.3V
tolerant and fail-safe. The threshold follows the VDDS_OSC0 levels
- Level of warm reset for MCU
and main domains RESET_REQz (VDDSHV0), MCU_RESETz (VDDSHV_MCU) matches the
IO supply group supply (1.8V or 3.3V)
- Reset inputs follow the slew
rate requirements (FS RESET, LVCMOS)
- Input slew rate when
open-collector output is connected (connecting through discrete push pull is
recommended) directly to the reset input
- Follow reset requirements
including slew rate and POR hold time when a non-TI power solution is
used
Schematic Review
Have you followed the below for the
custom schematic design:
- Cold and warm reset input
signals slew rate requirements are considered
- Cold reset input (MCU_PORz)
deassertion hold time (MCU_PORz input, 9.5ms minimum) after all supplies
ramps are provided as per the data sheet requirement
- Provision for filter
capacitor is provided at the input of the reset inputs (add 22pF (ball park
for place holder) capacitor as a filter option and DNI)
- Connection of reset inputs
when not used as per pin connectivity requirements
- Connection of push button
warm reset inputs through debouncing circuit (Schmitt trigger buffer
based)
Additional
- MCU_PORz input have a maximum
rise and fall time requirement when PMIC_POWERGOOD (Open-drain) is connected to
the MCU_PORz. Adjust the pullup to minimize the rise time (<200ns)
- MCU_PORz is fail-safe and 3.3V tolerant
- Connect the output from a push pull discrete buffer (with fast rise time) as
MCU_PORz input rather that slow rising open-drain output
- Not connecting a valid MCU_PORz causes unpredictable and random behavior,
because the device is not getting a valid reset, internal circuits are in random
states. Slow rising reset signal causes glitches internal to the processor reset
circuit
- LVCMOS inputs have slew rate
requirements. A schmitt trigger circuit is recommended for the slow ramp push
button RC connected to the processor warm reset inputs. Schmitt trigger circuit
is recommended when using a push button or an RC reset
- Provision for external ESD
protection for manual reset input added near to the reset signal
- Fail-safe operation when connected to external reset input signals. Applying an
external input before supply ramps causes voltage feed and affects the processor
performance
- Reviewed MCU_RESETz related errata