User's Manual

1323x Remote Control Motherboard
1323x Development Hardware Reference Manual, Rev. 1.0
4-6 Freescale Semiconductor
2. External DC source via header J14 - a standard 0.1 in. spacing 1x2 pin header allows for
connection of an external DC supply.
3. Battery Operation - a battery holder that accommodates two AA batteries is mounted on the
non-component (back) side of the board and provides for battery operation.
– If either the USB or external DC source is present, the battery source is disabled by
MOSFET transistor Q3
– The sources are all isolated and protected by Schottky diodes
– The minimum effective battery operating voltage is controlled by the use the FTDI
FT232RQ USB <> UART device - leakage current back through the FT232RQ UART
connections to the MC13233 on the MRB can cause the Q3 MOSFET to partially turnoff at
battery voltage below approximately 2.7-2.8 Vdc.
NOTE
To avoid current leakage through the USB device and to have lowest
minimum battery operating voltage for battery-only operation, remove the
following jumpers:
• P1, Pins 7-8
• P1, Pins 11-12
• P1, Pins 17-18
• P1, Pins 21-22
NOTE
When battery operation is used, the temperature range of the two board
system should be limited to within the specified temperature range of the
battery technology. Table 4-1 limits temperature range from 0 °C to +50 °C
when battery operation is applied.
Table 4-2 lists the voltage source attributes.
.
Table 4-2. 1323x-RCM Voltage Sources
Source Connector
Input Voltage
Range
Description
USB Port USB Type-B J15 4.4 V - 5.25 V • The input voltage range is set the USB Spec
• The voltage can be supplied by either a standard USB
cable connection or an AC to DC power adaptor that uses
the USB connector J15
• If a power adaptor is in use, the USB serial port cannot be
used