4.3 Startup Conditions

The board startup is managed by the power panagement unit MCP16502. The MCP16502 generates all the power supplies required by the processor and the system. For more details on the power-up conditions, refer to the MCP16502 data sheet. See Reference Documents.

Several startup scenarios are applicable depending on the status of the default board configuration:

  • The backup battery is not charged. This is the case for the board first use.
    • The backup battery is empty or below the value of Vthreshold.
    • When inserting the USB cable (J7) or the DC jack (J1), the system starts up on its own without any action on the nSTART button. See event "1" in the diagram below.
  • The backup battery is partially or fully charged.
    • The backup battery is charged above the value of Vthreshold.
    • When inserting the USB cable (J7) or DC jack (J1), the system does not start automatically and a short action on the nSTART button is necessary to start the system. See event "2" in the diagram below.
Figure 4-2. Start-Up Behavior Diagram
Note:
  1. The system can be powered off by a long pressure (> 4 seconds) on the nSTART button.
  2. It is possible to setup an automatic startup at each power insertion by mounting a C240 capacitor. With this configuration, the system starts automatically when the USB cable (J7) or the DC jack (J1) is connected. This is not the factory configuration.