SECTION 4: OPERATION
4.1 ELECTRICAL PERFORMANCE
The SPTUSBSC Series Dual USB Charging Port converts an aircraft (DC) input voltage within the range
specified to a 5V (DC) output. This output power is applied to each of the USB ports as an
independent circuit. The USB D+ and D- data lines communicate with the USB portable device to tell
the device it is a dedicated charging port (DCP), capable of a higher current than a standard USB port.
This allows the USB portable device to draw up to 3.4 amps per port. The unit is designed as a DC-to-
DC converter and supports multiple fast charging protocol technologies. Each port is independent and
reduces the output current to a safe level if the USB portable device draws excess current, is shorted
or has a fault.
If the temperature of the SPTUSBSC becomes elevated due to a fault or excessive load, the device will
seamlessly communicate with the USB portable device to lower the charge current. This allows the
device to continue charging while the unit returns to a temperature within designed limits. When the
temperature returns to a safe level the SPTUSBSC will automatically reestablish the higher charge
current level with the device and continue charging.
4.2 PROTECTIVE FEATURES
4.2.1 SHORT CIRCUIT PROTECTION
The SPTUSBSC is capable of surviving a short circuit event without permanent damage. The
unit goes into an over-current condition so that the average current is significantly reduced,
and the device is protected.
4.2.2 OVER-CURRENT PROTECTION
The SPTUSBSC monitors the current draw individually on each port. During an over-current
condition, the voltage is reduced.
4.2.3 LOW INPUT VOLTAGE SHUTDOWN
If the input voltage applied to the SPTUSBSC drops below 10 VDC the unit will shut down
until the applied voltage returns to a level within range.
4.2.4 OVER-TEMPERATURE
When the temperature of the SPTUSBSC becomes elevated, the unit communicates with the
USB portable device to reduce the charge current output (1 amp limit). When the
temperature returns to an acceptable level the unit automatically returns to a higher charge
current as required (up to 3.4 amps).
SECTION 5: CONFORMANCE
5.1 CONTINUED AIRWORTHINESS STATEMENT
No periodic scheduled maintenance or calibration is necessary for continued airworthiness of the
SPTUSBSC series Dual USB Charging Port. If the unit fails to perform to specifications, the unit must be
removed and serviced by Superior Panel Technology.
