VOLTAGE REFERENCE INPUT
The ADC-T allows for several different reference voltage configurations that may be used if other types of sensors are
connected. It may be necessary to remove (or adjust value) of the pull-up resistor that is installed on the underneath
side of the ADC-T. The reference voltage determines the voltage input range for all of the input channels ((2)
channels in differential mode). The following configurations are selectable from the setup page of the ADC-T. When
the ADC-T is configured for a user provided reference input, the ADC-T becomes a (3) channel converter since
channel four is used for the reference input. The ADC-T may also be configured to provide the internal reference as
an output if required. The reference output voltage will be provided at the channel four or channel 12 input terminal
(and becoming a (3) or (11) channel converter). The ADC-T8 has a separate reference input and allows use of all 8
input channels. Using the default reference setting will provide the greatest input noise rejection. Option 1 is the
default setting.
Option 1: 4.096 volt - allows a (0 to 4.1) volt input range with no reference output ((4) channel single ended)
allows a (-2 to +2) volt input range with no reference output ((2) channel differential)
Option 2: 5 volt - allows a (0 to 5) volt input range or (-2.5 to +2.5) in differential mode with no reference output
(4) channel single ended or (2) channel fully differential
Option 3: 4.096 volt - allows a (0 to 4.1) volt input range or (-2 to +2) in differential mode* with a reference output
(3) channel single ended reference output provided on channel 4 analog input.
The reference output voltage should be decoupled with a 2k series resister
Option 4: 3.3 volt - allows a (0 to 3.3) volt input range or (-1.65 to +1.65) volts in differential mode* with reference
(3) channel single ended reference voltage from AUX header is applied to the channel
4 analog input (also providing access to the reference voltage).
Option 4: 5 volt - allows a (0 to 5) volt input range or (-2.5 to +2.5) volts in differential mode* with reference
(3) channel single ended reference voltage from AUX header is applied to the channel
4 analog input (also providing access to the reference voltage).
Option 5: User supplied - must be in the range of 1 volt to 5 volts and should have an output impedance of 500
ohms or less (3) channel single ended reference voltage from user is applied to the
channel 4 analog input (providing access to the reference voltage).
Example: 2 volts applied to the channel 4 analog input provides a (0 to 2) volt input range single
ended or (-1 to +1) volts for differential inputs*.
*(2) channel fully differential (-) side of the channel 2 input is connected to GND.
When other types of sensors (such as humidity, pressure, etc.) are connected to the ADC-T temperature inputs it may
be necessary to remove or adjust the value of the pull-up resistor that is installed on the underside of the ADC-T. The
displayed sensor read out on the ADC-T Software Interface and data logger will need to be adjusted for the 10 bit AD
input by setting the scale, offset, precision and suffix parameters in the setup page.
TEMPERATURE SENSOR PIN-OUT (TO-92 package)
Page 8
USE CAUTION WHEN CONNECTING SENSORS - REVERSED POLARITY MAY CAUSE DAMAGE
Page 9
USB
Expansion Port A
Expansion Port B
AUX Header
+temperature input #1
+temperature input #2
sensor ground (-)
+temperature input #3
+temperature input #4
sensor ground (-)
+temperature input #5
+temperature input #6
sensor ground (-)
+temperature input #7
+temperature input #8
sensor ground (-)
USB
Expansion Port A
Expansion Port B
AUX Header
+temperature input #1
+temperature input #2
sensor ground (-)
+temperature input #3
+temperature input #4
sensor ground (-)
+temperature input #5
+temperature input #6
sensor ground (-)
+temperature input #7
+temperature input #8
sensor ground (-)
+temperature input #9
+temperature input #10
sensor ground (-)
+temperature input #11
+temperature input #12
sensor ground (-)
ADC-T8
ADC-T12
ADJ
(+)
(
-
)
Clip off adjust lead (not used)
Bottom View
(+)
(
-
)
Twisted pair to ADC-T terminal block (up to 1,000 feet)
CAT5 may be used. Shielded CAT5 will add protection
from lightning induced sensor damage
