User's Manual

CHAPTER3
UnderstandingConnectors
21
TheSOLARCELLConnector
The A753 remote wireless modem has a SOLAR CELL connector used
to interact with the device. The connector features the following pins:
• Solar Input, which enables charging the internal batteries.
 CAUTION To charge the unit without causing damage to the batteries or the
charging circuit, the following electrical characteristics must be
maintained:
• operating input voltage: 9 -10V
• maximum input current: 100 -300mA
• Battery, which enables powering external circuits. This pin is an
output-only pin. The maximum current drawn by the attached
circuit must not exceed 500 mA.
• RxD and TxD, which are used for serial communication (19200
baud) with the A753. The pinout of the SOLAR CELL connector is
shown in Figure 9.
Figure 9. The SOLAR CELL connector
Note: Unlike the usual power connectors, the A753 SOLAR CELL connector
features no external battery power supply. Thus, the unit must be
used with an installed internal battery or an external battery
connected to the DC INPUT connector.
 WARNING The serial communication line is 3V CMOS compatible. Therefore, a
special adapter cable must be used to reach the RS-232 levels.
You might want to charge the A753 with something other than the
standard solar panel. In this case you must provide the electrical
characteristics and configuration shown in Figure 10.
Figure 10. Configuration for charging the A753