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Internals

Power

  1. STANDBY_3V3 - Always on (manual switch), supplied from MAX1837EUT33 regulartor (VCC 5V -> 3.3V)
    • system MCU
      • VCC
      • USB port
      • I2C pullup
      • Reset pullup
    • RTC
    • FUSB302BMPX (USB-C with power delivery)
    • Qwiic I2C
    • Power rails latch (enables other power domains)
    • SYSCTL UART 1 connector (keyboard)
    • W25Q32JVSS (Flash?)
  2. VCC 5V - Supplied from charcher
    • MAX1837EUT33 (4.5V - 24V -> 3.3V) provides STANDBY_3V3
    • TPS5450DDAR when enabled via power latch provides 5V rail
    • TPS5450DDAR when enabled via power latch provides 3.3V rail
    • LM2830XQMFE/NOPB when enabled via power latch profides 1.1V rail
  3. USB_VBUS - Power form USB-C port 1 (PD port)
    • VCHG Power to charger
  4. +5V - Enabled via latch
    • AP22815A Power distribution switch; when enabled it powers USB_VBUS so any connected USB device for port 1 (PD port)
    • TLV320AIC3100 Audio codec for speaker and headphones
    • USB port 2 VBUS
    • TPD12S521 HDMI port
    • SoM (CPU card)
    • TUSB8041 USB Hub
    • Keyboard USB power
    • (not connected) Internal USB port for flashing SYS MCU (Receptacle) - this is via do not populate (DNP) resistor so it is not connected to +5V
  5. +3V3 - Enabled via latch
    • TXS0108EPW level shifter for modem (+1V8 -> +3V3)
    • MicroSD card slot
    • TPD12S521 HDMI port
    • IMX Reset pullup
    • DAC I2C pullup (audio)
    • IMX Uart pullup
    • NCV1117ST18T3G 3.3V -> 1.8V (1V8 supply)
    • Ethernet LED
    • USB Hub
    • M2 connectors
    • M2 phone modem
    • MIPI-DSI Display connector
  6. +1V1 - Enabled via latch
    • USBH_1V1 USB Hub
  7. +1V8 - Powered from +3V3 rail by TLV1117-18 (or ON SEMI NCV1117ST18T3G)
    • MIPI-DSI Dispaly connector
    • TXS0108EPW level shifter for modem (+1V8 -> +3V3)
    • MicroSD card slot
    • TLV320AIC3100 Audio codec for speaker and headphones

Summary:

  • Main power from batteries/charger or USB-C comes on VCC 5V.
  • Standby 3.3V power is regulated from the VCC 5V and is supplied to many components including charger MCU, system MCU, keyboard MCU (via UART connector), power latch.
  • Power latch is used to enable other rails: 5V, 3.3V (both regulate VCC 5V) and 1.1V (from 3.3V).
  • The 5V power is used many chips, USB power, SoM power, internal USB to keyboard.
  • The 3.3V power may chips and is used for SoM UART and I2C audio chip pullups.
  • The 1.1V is used only for USB Hub.
  • There is also 1.8V supply that regulates from 3.3V for display, modem, MicroSD card and audio.
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