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
- The recommendation is to
provide provision to connect an external resistor divider as per System
Power Supply Monitor Design Guidelines section of the data sheet for
early detect using VMON_VSYS
- For VMON_VSYS detection to be
effective, connect a DC voltage of 5V or higher
- VMON_VSYS - add a filter
capacitor. Refer processor data sheet section System Power Supply Monitor
Design Guidelines. The value of the capacitor is determined by the
designer based on the trip time requirement
- Direct connection of 1.8V to
VMON_1P8_SOC and 3.3V to VMON_3P3_SOC pins without any external filter
capacitors
Schematic Review
Follow the below list for the custom
schematic design:
- 1% tolerance resistors are
used for the VMON voltage divider resistors
- Addition of filter capacitor
and selection of capacitor value (select based on the power
architecture)
Additional
- The recommendation is to always implement the
voltage monitoring functionality using VMON_VSYS for early detection of supply
failure. VMON_VSYS is meant to be a power-fail indicator for the main input
(higher) voltage rail that enters the PCB. For example: 5V, 12V, or 24V. The
error associated with the VMON_VSYS monitor requires setting the threshold
significantly lower than the nominal to avoid false trigger. Refer System
Power Supply Monitor Design Guidelines section of the data sheet