Specifications

Section 1. Installation and Maintenance
1-15
TABLE 1.8-1. Current Sourcing Limits
Terminals Current Source Limit
SW12 < 900 mA @ 20°C
< 729 mA @ 40°C
< 630 mA @ 50°C
< 567 mA @ 60°C
< 400 mA @ 80°C
12V + SW12 < 1.85 A @ 20°C
< 1.50 A @ 40°C
< 1.30 A @ 50°C
< 1.17 A @ 60°C
< 0.85 A @ 80°C
5V + CSI/O < 200 mA
Make certain that the primary source of power for the CR3000 can sustain the
current drain for the period of time required. Contact a CSI applications
engineer for help in determining a power budget for applications that approach
the limits of a given power supply’s capabilities. Be particularly cautious
about any application using solar panels and cellular telephone or radio,
applications requiring long periods of time between site visits, or applications
at extreme temperatures.
TABLE 1.8-2. Typical Current Drain for Some CR3000 Peripherals
Typical Current Drain (mA)
Peripheral Quiescent Active
AM25T 0.0005 1
COM210 Phone Modem 0.12 140
SDM-INT8 0.4 13-20
1.9 Controlling Power to Sensors and Peripherals
Controlling power to an external device is a common function of the CR3000.
Many devices can conveniently be controlled with the SW-12 (Switched 12
Volt) terminals on the CR3000. Table 1.8-1 shows the current available from
SW-12 port.
Campbell Scientific’s SW12V Power Switch Assembly can also be used
control power to one or two external devices simultaneously. It is comprised
of an 18 inch (45 cm) length of cable that contains an internal switch. A
control port controls the status of the switch, thereby controlling whether 12
Vdc power is passed to an external peripheral.
Applications requiring more control channels or greater power sourcing
capacity can usually be satisfied with the use of Campbell Scientific’s
A21REL-12 Four Channel Relay Driver, A6REL-12 Six Channel Relay
Driver, SDM-CD16AC 16 Channel AC/DC Relay Module, or by using the
control (C1-C8) ports as described in Section 1.9.1