DMS-20 Datel, DMS-20 Datasheet - Page 4

• Manufacturer Part Number: DMS-20
• Description: LCD SEGMENTED NUMERIC CHARACTER MODULE
• Manufacturer: Datel

DMS-20LCD
2. Differential Input Configurations: Differential measurements
3. Engineering Scaling: For measuring voltages greater than the
can be made with either 5V-powered or 9V-powered meters.
Figure 3, though not a practical real-world application, uses a
voltage divider to demonstrate the concept of a differential input
signal. Be careful not to exceed the ±2V common mode voltage
limitation for 5V powered meters.
full scale input range of a given meter, the input signal must be
attenuated. A simple voltage divider (similar to that shown in
Figure 4) will scale the input to within the range of the selected
meter. R1 and R2 should be precision, ±1%, metal-film resistors
with absolute TCR's less than 50ppm/°C. See Ap Note 4 for more
information on engineering scaling.
Figure 3. Differential Input Configuration
R1 + R2
50k < R1 + R2 < 10M
Figure 4. Input Attenuation Circuit
R2
(5V-Powered Models)
x V
IN
= Reading
3 ½ D I G I T , L C D D I S P L A Y D I G I T A L P A N E L V O L T M E T E R S
Applications
4
5. Process Control (4-to-20mA) Measurements: In many
4. Floating Signal Source Measurements: Floating signals can
be measured using the circuits shown in Figures 5 and 6. Figure
5 uses a 5V-powered meter. Figure 6 uses a 9V-powered meter.
Connecting pin 10 (ANALOG COMMON) to (–) INPUT LO (pin
12) provides the reference point for the meter's input.
A "floating" input is a signal that has no galvanic connection to
the meter's power supply. In the figures below, the 1.5V battery
illustrates a true floating input.
common process-control applications, a 4-to-20mA current loop
is used to transmit information. Because DMS-20LCD meters
have such high input impedance, a simple shunt resistor across
the meter's input can be used to convert the loop current to a
voltage. See Figure 7. The value of the shunt resistor is a
Figure 5. Floating Input Measurements
Figure 6. Floating Input Measurements
(5V-Powered Models)
(9V-Powered Models)