Campbell Scientific AM25T 25-Channel Solid State Multiplexer - Manual (Page 5)

AM25T Solid State Multiplexer
1. General
The AM25T Multiplexer increases the number of channels for measuring
thermocouples or voltage sensors with Campbell Scientific dataloggers. The
AM25T is positioned between the sensors and the datalogger. The datalogger
controls the AM25T's solid state relays, sequentially connecting each sensor to
the datalogger.
The AM25T is not suitable for resistive bridge measurements (high impedance
of the solid state relays) or multiplexing power (25 mA maximum switching
current).
A maximum of 25 thermocouples (differential voltage measurement) can be
multiplexed by an AM25T. Single-ended voltage measurements are not
recommended (Appendix A).
The AM25T must be used in a non-condensing environment. An enclosure is
required for field use. In applications where one or two multiplexers are
deployed in the field, the ENC12/14 can be used. The ENC16/18 can be used
to house several multiplexers at the same site.
1.1 AM25T Specifications
POWER
Unregulated 9.6 V to 16 V; 12 VDC Nominal
CURRENT DRAIN
Quiescent: 0.5 mA
Active: 1.0 mA (typical)
ENABLE
Inactive: < 0.9 V
Active: 3.5 to 5.0 V (7 V max.)
CLOCK
The relays are advanced on the falling edge of the clock pulse (transition from
>3.5 V to <1.5 V; 7 V max.). The minimum clock pulse width is limited by
the datalogger.
Minimum ON time 50 microseconds
Minimum OFF time 60 microseconds
1