General
Review and verify the following for the custom schematic design:
- Reviewed above "Common
checklist for all sections" section of the user's guide.
- The configured output voltage level and the
current sizing (rating) for the supply rails.
- Output voltage feedback connection and feedback
resistor divider tolerance.
- Selected discrete DC/DC supports active
discharge.
- Discrete DC/DC output slew rate meets the
processor requirements.
- Sequencing of the supply rails as per the
processor requirements.
- MCU_PORz input (DC/DC PG
output) slew rate.
- Voltage rating of the selected capacitors
considering derating.
- Implementation of SD card interface IO supply
supporting UHS-I SD card.
- Implementation of VPP (eFuse
programming) supply.
- Naming of the supply rails.
- Matching of the Discrete DC/DC or Discrete LDO
voltage levels.
- Net name matches (same name) for processor and
attached devices IO supplies.
Schematic Review
Follow the list below for the custom schematic
design:
- The resistor divider value
including tolerance connected to the feedback to generate the required
output supply voltage matches with the calculated value for discrete DC/DC
or LDO.
- DC/DC or LDO outputs current
sizing.
- Discrete DC/DC or LDO PG
outputs have the required pullup and connects to other DC/DC or LDO EN for
supply sequencing.
- DC/DC or LDO outputs slew
rate matches the processor slew rate requirements.
- MCU_PORz input (DC/DC PG
output) slew rate (connect through discrete push-pull output type buffer)
and L to H delay (MCU_PORz input low hold time for clock start-up and
stabilization) implementation after all the processor supplies ramp.
- MCU_PORz input low hold time after supplies ramp, in case the DC/DC PG
output connects directly to the processor MCU_PORz input.
- Implementation of VPP (eFuse programming) supply including capacitors to
support load current transients and output enable (EN).
- Implementation of LDO for SD card interface IO supply for supporting UHS-I
SD card.
- Naming of the supply rails (indicate configured output voltage).
- Matching of the Discrete DC/DC or Discrete LDO voltage levels with the
supply requirements for the processor and attached devices.
- Voltage rating of the
selected capacitors considering derating (> twice the worst-case applied
voltage is a commonly used guideline).
- Discrete power device
selection including output supply voltage rails (operating
voltage/amplitude) and current rating, active discharge, provision to
enable, slew rate control, residual voltage detection (Allow to power-up
only when the supply voltages are < 300mV after power-down).
Additional
- In case custom board design power architecture is
based on TI power, the recommendation is to obtain a detailed review of the
implementation with the relevant business unit or product line.
- A 0Ω resistor or jumper is recommended at the
output of the discrete DC/DC, LDO for isolation or current measurement for the
initial board build. The recommendation is to add TPs for measurement. The
recommendation is to follow kelvin current sense connection for connecting TPs
to 0Ω resistor or jumper.
- The recommendation is to add a zener at the
output of discrete DC/DC or discrete LDO when adjustable output type discrete
DC/DC or discrete LDO are used.