DMS-20LCD ETC-unknow, DMS-20LCD Datasheet - Page 4

• Manufacturer Part Number: DMS-20LCD
• Description: 3 1/2 Digit, Lcd Display Low-cost, Subminiature Digital Panel Voltmeters
• Manufacturer: ETC-unknow

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.
8 5 - 2 6 4 V a c
8 5 - 2 6 4 V a c
–
+
V
A C t o D C C o n v e r t e r
I N
R E F I N
R E F O U T
Figure 3. Differential Input Configuration
R1 + R2
D M S - P S 1 - C M
50k < R1 + R2 < 10M
R 1
R 2
D A T E L
Figure 4. Input Attenuation Circuit
R2
D P 1
A C t o D C C o n v e r t e r
D M S - P S 1 - C M
D A T E L
+ 5 V S U P
8
7
6
( – ) I N L O
( + ) I N H I
(5V-Powered Models)
x V
1 1
1 2
1
D M S - 2 0 L C D - 1 - 5
IN
+ 5 V S U P
= Reading
D M S - 2 0 L C D - 1 - 5
1
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
5 V R E T
3
5 V R E T
3
1 1
( + ) I N H I
1 2
( – ) I N L O
8
R E F O U T
7
R E F I N
R 1
R 2
R 3
1 k
1 k
1 k
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
8 5 - 2 6 4 V a c
C E L L
1 . 5 V
C E L L
1 . 5 V
–
A C t o D C C o n v e r t e r
Figure 5. Floating Input Measurements
–
Figure 6. Floating Input Measurements
+
D M S - P S 1 - C M
D A T E L
A N A C O M M
( – ) I N L O
( – ) I N L O
( + ) I N H I
( + ) I N H I
(5V-Powered Models)
(9V-Powered Models)
B A T T E R Y
9 V
1 1
1 2
+ 5 V S U P
1 1
1 0
1 2
+ B A T
1
1
D M S - 2 0 L C D - 1 - 5
D M S - 2 0 L C D - 1 - 9
–
5 V R E T
3
– B A T
3
D P 1
6
D P 1
6
7
8
R E F O U T
R E F I N
8
R E F O U T
7
R E F I N