dms-30lcd ETC-unknow, dms-30lcd Datasheet - Page 5

• Manufacturer Part Number: dms-30lcd
• Description: Dpm Lcd 2vdc 3.5dig 9-14v Supply
• Manufacturer: ETC-unknow

scale reading) and a desired full scale display reading of
1000 (with an input of 20mA), V
To calibrate the circuit of Figure 7, perform the following:
1. With 4mA applied, adjust the 50kΩ potentiometer (R2) to
2. With 20mA applied, adjust the gain-adjust potentiometer on
APPLICATIONS
6. Power Supply Monitoring: A popular application for DATEL’s low-
display a reading of "000" (assuming that is the desired
reading).
the back of the meter to display a reading of "1999". For different full
scale readings, alter the R
power LCD meters is monitoring the supply voltage in battery-oper-
ated portable equipment. Figure 8 demonstrates how a 9V-powered
DMS-30LCD can be used to monitor its own supply. The meter used
is the DMS-30LCD-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 bat-
tery voltage falls across the inputs to the meter:
Where:
Example: For a meter with a 2V full scale input (1.999 full
4-20mA
+
–
120 VAC
R
R
R
Shunt
V
Shunt
Shunt
I
AC to DC Converter
Fsr
Fsr
R1
= 1.000V/(0.020 – 0.004)A
Figure 7. 4-to-20mA Current Loop Operation
= R1 = V
= Full scale reading (in Volts)
= Relative full scale current (in Amps)
= 1.000V/0.016A = 62.5 Ohms
ANA COMM
50k
(–) IN LO
(+) IN HI
R2
Fsr
Shunt
(5V-Powered Models)
/ I
Fsr
Fsr
+5V SUP
value accordingly.
= 1.000 Volts
1
DMS-30LCD-1-5
5V RET
3
www.murata-ps.com/dpm
8
7
REF OUT
REF IN
7. External Gain Adjustment: Connect REFERENCE OUT
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 fi rst measuring the actual battery volt-
age with another meter and then adjusting the gain-adjust potentiom-
eter on the back of the DMS-30LCD until a similar reading is obtained.
If possible, the resistors in the divider should be ±1% metal-fi lm types
with TCR’s less than 50ppm/°C.
(pin 8) to REFERENCE IN (pin 7) for normal, factory calibrated, opera-
tion. Use the +1.23V REFERENCE OUT (pin 9) for applications need-
ing external gain adjustment. Figure 9 shows the wiring confi guration
for each model. Calibration is performed with a precise, near-full-scale,
input voltage.
12
For 5V models tie
(–) IN LO to pin 3
CALIBRATOR
VOLTAGE
3½ Digit, LCD Display Digital Panel Voltmeters
REF OUT
(–) IN LO to pin 10
For 9V models tie
REF IN
7
COM
8
OUT
BATTERY
(R1 + R2 + R3)
9V
+BAT
R2
1
Figure 9. External Gain Adjustment
Figure 8. Power Supply Monitor
(–) IN LO
(+) IN HI
–
+
5V RET
DMS-30LCD Series
ANA COMM
DMS-30LCD-1-9
11
12
(9V-Powered Models)
3
06 Jan 2011 MPM_DMS30LCD.D02 Page 5 of 6
= 0.1
10
–BAT
3
10 to 20 Turns
8.45k, 1%
NC
8
1k
DMS-30LCD
5
DP2
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10 to 20 Turns
8.45k, 1%
12
11
(–) IN LO
(+) IN HI
1k
REF IN
7
1.23V REF
9
Connections
±20V models
Connections
for ±200mV
for ±2V and
models
45.3k
10.1k
45.3k
R1
R2
R3