XO DC Input
This page attempts to detail the different tests that an XO DC power input should pass.
Absolutes
These are static tests of the input protection circuitry:
Valid Input Voltage
The laptop shall operate and charge the battery when supplied with any voltage between 11V and 24V (inclusive).
Overvoltage
The laptop shall not be damaged by the application of voltages up to 40V, for any length of time.
Applying a voltage higher than 40V shall not result in fire, but may destroy the internal fuse.
Undervoltage
The laptop shall not draw power from the DC power input when supplied with voltages between 0V and 9V.
Negative Voltage
The laptop shall not be damaged by the application of a negative voltage up to -38V, for any length of time.
Applying a negative voltage larger than -38V shall not result in fire, but may destroy the internal fuse.
Maximum Power Draw
The laptop shall never draw more than 25 Watts of power from its DC power input. This is usually tested with the laptop on and running processor tests from Open Firmware, while charging a low battery (open circuit battery voltage less than 5.6V).
The actual power limit depends on the laptop model. For XO-1, this number was 17 Watts.
Behavior when plugging/unplugging
Power draw when turned off
The power draw of the laptop from the battery shall not exceed 2 mA when the laptop is turned off and no external power is provided.
Power brownout while charging
The laptop shall tolerate quick interruptions in DC power input without disturbing the battery charging. If must be confirmed that the battery charging continues properly, not just that the indicators indicate that charging is continuing.
Seen as Trac 9983
Suspend/Resume
Inserting power while suspended
If power is supplied to the DC power input while the laptop is suspended, the laptop should automatically begin powering itself from the external power source. If necessary, the battery should begin charging. All indicators (power and battery LEDs) should properly indicate that external power has been supplied.
Removing power while suspended
If power is removed from the DC power input while the laptop is suspended, the laptop should continue operation from battery. All indicators (power and battery LEDs) should properly indicate this loss of external power.
Seen as Trac 10369
Solar
Operation from underpowered solar panels
Proper MPPT operation
Multiple laptops sharing a panel
Multiple laptops should be able to share a solar panel which has an adequate power rating.
Error Conditions
Indication of critically low battery
The laptop shall indicate that the battery is critically low by turning on the red battery LED when the laptop is turned on.
Seen as Trac 3610, Trac 5858, and Trac 10033
The laptop shall not indicate the battery status when the laptop is turned off.
Seen as Trac 10668
Inserting power while battery is low
Applying power to the laptop while the battery is low shall not cause the laptop to power off.
Seen as Trac 2182