General
Review and verify the following for the custom schematic design:
- Reviewed above "Common
checklist for all sections" section of the user's guide
- PMIC selection (OPN) based on the input supply and output voltages (core
voltage, IO voltage and DDR voltage configuration)
- PMIC checklist for addition of required input and output capacitors
including values, feedback connection, and pin connections
- Voltage rating of the selected capacitors considering derating
- Configuration of the recommended PMIC control and IO signals
- Connection of the required control signals for processor IO supply
sequencing and slew rate control
- Processor I2C instance used to interface to PMIC
- Processor to PMIC and PMIC to processor IO interface connections
- Naming of the supply rails (indicate configured output voltage level)
- Net name matches (same name) for processor and attached devices IO
supplies
- Connection of interrupt, MODE/RESET, and EN/PB/VSENSE signals and connection
of the required pulls for the PMIC IOs
Schematic Review
Follow the below list for the custom schematic
design:
- Configuration of the PMIC output to match the processor and attached devices
IO supply operating voltages as per the custom board requirements
- The custom board PMIC implementation with the SK schematic implementation
for capacitors quantity, size and values, IOs connection
- Connection of the PMIC buck output feedback (tie the feedback after the
output bulk capacitors)
- SD card IO voltage control (VSEL_SD) pin connection (3.3V during processor
start-up or board reset and switched to 1.8V for UHS-I SD card support)
- PMIC nRSTOUT0 slew (pullup value) when connected directly to processor
MCU_PORz input (recommend using a discrete push-pull output type
buffer)
- Connection of the required control signals for processor IO supply
sequencing (load switch EN for processor and attached device IO supply
voltage and provision for load switch output voltage slew rate control using
external capacitor)
- Voltage rating of the selected capacitors considering derating (> twice the
worst-case applied voltage is a commonly used guideline)
- Matching of the PMIC output voltage level with the supply requirements for
the processor and attached devices (based on the OPN)
- Processor I2C instance used to interface to PMIC (Follow SK or review the
required I2C instance based on the use case)
- Configuration of discrete DC/DC outputs and LDOs used along with the PMIC to
generate additional supply rails
- External LDO implementation for generating VPP supply (eFuse programming),
LDO output enable (EN) control, addition of bulk and decoupling capacitors
considering load current transient and provision for isolation resistor for
testing the VPP supply output enable timing
Additional
- In case custom board design power
architecture is based on TI PMIC, the recommendation is to obtain a detailed
review of the implementation done with the PMIC team (business unit or product
line).
- A 0Ω resistor or jumper is recommended at the
output of the PMIC and 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 connect the feedback for
the PMIC buck output after the bulk capacitor. The recommendation is to connect
the feedback to make sure the removal of the 0Ω resistor does not affect the
PMIC operation (connect on the PMIC side of the resistor).
- Since the PMIC performs a warm reset, connecting
the RESETSTATz output from the processor to the MODE/RESET input of PMIC can be
optional. Adding a 0Ω resistor and marking the resistor as DNI is recommended.
PMIC internal pull is enabled.
- The recommendation is to show the PMIC input bulk
capacitors for buck (DC/DC) inputs and VSYS separately and near to each of the
pin for ease of placement and routing.
- The recommendation is to review and follow the
FAQs related to residual voltage.
- In case a non-TI PMIC is used, the recommendation for custom board designers is
to review and follow the relevant processor collaterals including the
processor-specific data sheet and Maximum Current Ratings application
note. The recommendation is to review the Recommended Operating
Conditions, Supply Slew Rate Requirements, MCU_PORz Timing
Requirements, Power-Up Sequencing and Power-Down Sequencing
sections of the processor-specific data sheet and confirm the selected PMIC
based power architecture supports the above requirements and residual voltage
(RV) check.