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Número de pieza | DMS-20 | |
Descripción | LCD SEGMENTED NUMERIC CHARACTER MODULE | |
Fabricantes | Datel | |
Logotipo | ||
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ww Digital Panmel VoltmetersFeatures
o• Lowest cost
• Lowest power, 2mW
.c• Subminiature size:
1.38" x 0.88" x 0.43"
35mm x 22mm x 11mm
U• Large (0.37"/9.4mm), enhanced-
t4contrast LCD display
• Backlit displays optional
e• Epoxy-encapsulated, 12-pin DIP
• Panel or pc-board mountable
e• 4 differential input voltage ranges
h• High accuracy, ±1 count (±0.05%)
• Single +5V supply or 9V battery
S• Low-battery annunciator
ta• User-selectable decimal point placement
• 0 to +60°C temperature range
DMS-20LCD Series, 3½ Digit, LCD Display, Digital Voltmeters represent the
ultimate combination of low price, low power, small size and high performance in digital
meters. Epoxy encapsulated in a subminiature (1.38" x 0.88" x 0.43"), 12-pin DIP
package, these completely self-contained, fully operational meters offer a combination
of ruggedness, long-term reliability and component-like ease-of-use simply not
available in any other meters.
Incorporating a precision reference and a factory-calibrated, autozeroing A/D
converter, DMS-20LCD meters are extremely accurate (±1 count) and are only slightly
larger than their 0.37"/9.4mm, enhanced-contrast, LCD displays. All models incorpo-
rate a built-in bezel and are easily mounted in either panels or pc boards. Both backlit
and non-backlit versions are available.
DMS-20LCD meters have 4 differential input voltage ranges (±200mV, ±2V, ±20V
and ±200V) and a user-friendly input structure. Input impedance is a minimum 800kΩ.
CMRR is typically 86dB with a CMV of ±2V. Non-inverting inputs are overvoltage
protected to ±100V (±250V for the ±200V input model).
All DMS-20LCD meters operate from a single +5V supply (drawing 400µA) or a
single +9V supply/battery (drawing 230µA). All models have a low-battery ("B")
annunciator and feature autopolarity changeover and overrange indication.
Also available is an application/evaluation board (DMS-EB2) that plugs directly onto
the back of any DMS-20LCD allowing direct inputs for common applications such as
4-20mA inputs, zero/gain adjust, decimal point location, and input voltage dividing.
.Da+5VSUPPLY/ 1
+BATTERY
w2
N.C.
w5V RETURN/ 3
m–BATTERY
w .co4
DP 3
+5V
DC/DC 3
CONVERTER
0 Vdc
J1
–5V
A/D
CONVERTER
DATA
V+
V–
2
0.01µF
» +2.0V
1
R2
R1
909k
12
(–) INPUT LO
11
(+) INPUT HI
10 ANALOG
COMMON
9
N.C./BACKLIGHT 4
t4U5
DP 2
hee6
DP 1
8
REFERENCE OUT
+5V
7
REFERENCE IN
taS1 R2 is not used on ±200mV (-0) models or ±2V (-1) models.
aR2 = 100k on ±20V (-2) models and 9.1k on ±200V (-3) models.
.D2 Only used on ±200mV (-0) and ±2V (-1) models.
3 DC/DC converter is not used on 9V-powered models,
J1 is connected.
4 Used on backlit models only.
N.C. for non-backlit models.
wwwFigure 1. DMS-20LCD Series Simplified Schematic
DATEL, Inc., Mansfield, MA 02048 (USA) • Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 • Email: [email protected] • Internet: www.datel.com
1 page 3½ D I G I T, L C D D I S P L AY D I G I TA L PA N E L V O LT M E T E R S
DMS-20LCD
Applications
function of the scaling requirements of the particular application and
can be calculated using the following equation:
RShunt = R1 = VFsr / I Fsr
Where: VFsr = Full scale reading (in Volts)
IFsr = Relative full scale current (in Amps)
Example: For a meter with a 2V full scale input (1.999 full
scale reading) and a desired full scale display reading of
1000 (with an input of 20mA), VFsr = 1.000 Volts
RShunt = 1.000V/(0.020 – 0.004)A
RShunt = 1.000V/0.016A = 62.5 Ohms
To calibrate the circuit of Figure 7, perform the following:
1. With 4mA applied, adjust the 50kΩ potentiometer (R2) to
display a reading of "000" (assuming that is the desired
reading).
2. With 20mA applied, adjust the gain-adjust potentiometer on
the back of the meter to display a reading of "1999". For different
full scale readings, alter the value of RShunt accordingly.
4 -2 0 m A
R1
11
(+ ) IN H I
10
ANA CO M M
D M S -2 0 L C D -1 -5
8
REF O UT
12
( ) IN L O
1
R 2 +5V S U P
50k
3
5V R E T
7
R E F IN
8 5 -2 6 4 V a c
D A TEL
D M S -P S 1 -C M
A C to D C C o n v e rte r
Figure 7. 4-to-20mA Current Loop Operation
(5V-Powered Models)
6. Power Supply Monitoring: A popular application for DATEL's
low-power LCD meters is monitoring the supply voltage in battery-
operated portable equipment. Figure 8 demonstrates how a 9V-
powered DMS-20LCD can be used to monitor its own supply. The
meter used is the DMS-20LCD-1-9. A three-resistor voltage
divider is used to attenuate the battery voltage and also to satisfy
the requirement that the input voltages applied to pins 12 and 11
be at least 1.5 Volts above and below the battery voltage applied
to pins 1 (+BATTERY) and 3 (–BATTERY). The divider should be
designed so that 1/10th the battery voltage falls across the inputs
to the meter:
R2 = 0.1
(R1 + R2 + R3)
Therefore, the 9V battery voltage appears to the meter inputs
as 0.9V. With the decimal point moved to its DP2 position
(pin 5 tied to pin 3), the meter reads 9.00 Volts.
The circuit can be calibrated by first measuring the actual
battery voltage with another meter and then adjusting the gain-
adjust potentiometer on the back of the DMS-20LCD until a
similar reading is obtained. If possible, the resistors in the
divider should be ±1% metal-film types with TCR's less than
50ppm/°C.
REF OUT 8
DMS-20LCD-1-9
11
(+) IN HI
REF IN 7
1
+BAT
9V
BATTERY
–
12
(–) IN LO
3
–BAT
5
DP2
R1
45.3k
R2
10.1k
R3
45.3k
Figure 8. Power Supply Monitor
(9V-Powered Models)
7. External Gain Adjustment: Connect REFERENCE OUT
(pin 8) to REFERENCE IN (pin 7) for normal, factory calibrated,
operation. Use the circuit shown in Figure 9 for applications
needing external gain adjustment. Calibration is performed with
a precise, near-full-scale, input voltage.
OUT
VOLTAGE
12 CALIBRATOR
COM
11
(+) IN HI
DMS-20LCD
3
5V RET/
–BAT IN
12
(–) IN LO
10
ANA
COMM
87
NC REF
IN
8.06k, 1%
2kQ
1
+5V IN/
+BAT IN
Connections
for ±2V, ±20V
and ±200V models
17.4k, 1%
For +5V models, tie (–) IN LO to pin 3.
For +9V models, tie (–) IN LO to pin 10
732, 1%
200Q 24.3k, 1%
Q = 10 to 20 Turns
Connections
for ±200mV
models
Figure 9. External Gain Adjustment
5
5 Page |
Páginas | Total 6 Páginas | |
PDF Descargar | [ Datasheet DMS-20.PDF ] |
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