Campbell Scientific CR3000 Micrologger - Manual (Page 89)

Section 7. Installation
89
Figure 32: Connecting to vehicle power supply
7.4.5 Powering Sensors and Devices
Read More! See Power Sources
(p. 82).
The CR3000 wiring panel is a convenient power distribution device for powering
sensors and peripherals that require a 5- or 12-Vdc source. It has 2 continuous 12-
Vdc terminals (12V), one program-controlled switched 12 Vdc terminal
(SW12V), and one continuous 5 Vdc terminal (5V). SW12V, 12V, and 5V
terminals limit current internally for protection against accidental short circuits.
Voltage on the 12V and SW12V terminals can vary widely and will fluctuate with
the dc supply used to power the CR3000, so be careful to match the datalogger
power supply to the requirements of the sensors. The 5V terminal is internally
regulated to within ±4%, which is good regulation as a power source, but typically
not adequate accuracy for bridge sensor excitation. Table Current Sourcing Limits
(p. 89)
lists the current limits of 12V and 5V. Greatly reduced output voltages
associated with 12V, SW12V, and 5V due to current limiting may occur if the
current limits given in the table are exceeded. Information concerning digital I/O
control ports is available in Digital I/O Ports
(p. 333).
Table 6. Current Source and Sink Limits
Terminal Limit
1
VX or EX (voltage excitation)
2 ±25 mA maximum
IX (current excitation) ±2500 µA maximum
CAO (continuous analog voltage output) ±15 mA maximum
SW12V
3 < 900 mA @ 20°C
< 630 mA @ 50°C
< 450 mA @ 70°C
12V + SW12V (combined)
4 < 3.00 A @ 20°C
< 2.34 A @ 50°C
< 1.80 A @ 70°C
< 1.50 A @ 85°C