PowerTree

Power Tree

MAXREFDES178 is mainly powered by MAX20303 PMIC.

MAX20303 is a highly integrated PMIC with multiple buck, buck-boost converters, LDOs, Li+ battery charger, battery fuel gauge and haptic driver.

Safe LDO of the PMIC is an always-on output when a USB cable is plugged in. This LDo regulator is utilized to power analog switches and comparators next to the USB Type-C connector. These integrated circuits are used for USB Type-C debugger connection. Please refer to Debugger Operation for details.

Buck1 converter of PMIC is configured to generate 1.8V rail. This rail powers:

• MAX7325 I2C Port Extender
• MAX9867 Stereo Audio Codec
• BMI160 IMU (Accelerometer+Gyroscope)
• TFT LCD
• QSPI Flash Memory
• MAX6817 Button Debouncer
• Analog Switches for USB Type-C debug operation of AI Board

Buck2 converter of the PMIC is configured to generate 2.8V_AUX rail. This rail powers:

• TFT LCD
• Capacitive Touch Screen
• Micro SD Card
• OVM7692 Image Sensor (AI Board)
• MAX78000 - Image (VREGI input of SIMO, via MAX34417 power accumulator)
• MAX78000 - Audio (VREGI input of SIMO, via MAX34417 power accumulator)

LDO1 of PMIC is configured to operate as a load switch. This load switch controls 1V8_AUX output. When enabled, this rail powers:

• MAX9867 Stereo Audio Codec (AI Board)
• QSPI SRAM (AI Board)
• Microphone (AI Board. Via another load-switch)
• Debugger interface circuits (AI board)

LDO2 of PMIC generates 3.3V for 3V3_AUX rail. When enabled, this rail powers:

• MAX34417 power accumulator (AI board)
• RGB LEDs (AI board)

SYS_OUT of the PMIC is the smart power selector switch output. This rail powers:

• MMAX38643 which is set to 2.8V (2V8 rail)
  • MAX32666 SIMO input is powered by this rail.
  • Micro SD card is powered by this rail.
• MAX1574 White LED Flash Driver (AI board)
• 2x MAX38642 Buck Regulators. (AI Board) These buck regulators are normally disabled. Each regulator can be enabled by the dedicated MAX78000 processor; image our audio. These regulators are connected to the CNN supply of the corresponding MAX78000 processor. Normally MAX78000 internal SIMO regulator is sufficient to power CNN block itself. But for very heavy networks, an external regulator might be needed for powering the CNN unit.

Boost Output of the PMIC powers the TFT LCD backlight. It is set to 9.6V.

Haptic Output of the PMIC is not used. But t is accessible on header pins.

MAX32666 and MAX78000 processors have built-in SIMO (Single Inductor Multiple Output) units to generate necessary voltages with great efficiency.

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