2
Introduction
• Low power consumption
• 5 or 9 volt dc operation (customer selectable)
• Annunciators for common engineering units and decimal point
• Auto-polarity
• 200mV full scale reading
In 5V mode each module generates its own -5V supply which enables it to measure signals with the same
common zero as the supply. Connections are brought out to enable the module to operate in various modes
including single ended, ratio measurement and differential. Different modes are selected by linking PCB
solder pads which are provided for the purpose.
Min
Typ
Max
Units
Accuracy (±1 LSD)
0.05
0.1
%
Linearity
±1
LSD
Sample Rate
3
per sec
Temperature Stability
30
ppm/°C
Operating temperature
0
50
°C
Storage temperature
-20
70
°C
Supply voltage (5V mode)
3
5
7
Vdc
Supply voltage (9V mode)
7
9
12
Vdc
Supply current
2
mA
Backlight current (HED281/DPM951)
80
mA
Backlight current (HED282DPM952)
160
mA
Input impedance
100
M
Ω
Specification
Internal Reference Voltage
The internal reference voltage (REF HI) is set by VR1.The voltage is factory set at 100.0mV but may be
trimmed to suit individual applications, eg. to compensate for the inaccuracy of external resistors when using
scaling configurations.
HED281/282 only:
This is a 9 turn pot for greatest accuracy.
Power Supply Selection
5 volt mode
9 volt mode
LK5 Open
LK5 Shorted
LK6 Shorted
LK6 Open
Application Circuits (page 13)
Note:
In the application circuits, power is supplied on pins +V and 0V.
Caution:
Where the measurement voltage is referenced to the supply voltage (in either current or voltage applications)
the voltage on IN HI or IN LO must not exceed ±4.5V for 5V supply or ±3.5V for 9V supply.
Scaling Configuration
You can configure the HED282/DPM952 for different voltage ranges by soldering resistors in the positions
RA and RB. As supplied RA has a 0
Ω
resistor fitted. On the HED281/DPM951, RA and RB must be fitted
externally.
0.1% resistors are required to maintain an accuracy of 0.1%. This may be relaxed if an accuracy less than
this is required.
