Falcon HED271 Manual De Instrucciones página 2

Introduction
•Auto-polarity
• Low power consumption • 5 or 9 volt dc operation (customer selectable)
• Low battery warning (9 volt operation only)
•Annunciators for common engineering units and decimal point
• Hold function with annunciator
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.
Specification
Accuracy (±1 LSD)
Linearity
Sample Rate
Temperature Stability
Operating temperature
Storage temperature
Supply voltage (5V mode)
Supply voltage (9V mode)
Supply current
Backlight voltage
(see next page, CN1)
Backlight current (HED271/DPM961)
Backlight current (HED272DPM962)
Input impedance
Power Supply Selection
The low battery function must be disabled in 5V operation. In 9V
operation, it may be enabled or disabled.
Analogue Inputs
IN HI, IN LO and REF HI are all differential inputs. They respond to the voltage across them and not to the
voltage with respect to the power supply. The only exception to this is in 5V mode where the analogue
common and VSS have been connected together. There is a limit to the voltage which can be measured
using a differential input and this is known as the common mode range.
Caution
No input may be taken outside the range VDD minus 0.5V and VSS plus 1.0v. If there is a danger that any
input may be taken outside these limits, it is necessary to fit a resistor of suitable value to limit the current to
100µA in series with the input or damage to the unit may occur.
The voltage on IN HI or IN LO must not exceed ±4.5V for 5V supply or ±3.5V for 9V supply.
The maximum voltage allowed for any connection to the PCB is 48V. When measuring voltages
greater than 48V, the scaling resistors must be fitted externally.
Application Circuits (page 13)
Scaling Configuration
You can configure the units for different voltage ranges by soldering resistors in the positions RA and RB on
the PCB. The unit has a 0Ω resistor fitted in position RA. This must be removed before fitting the RA and RB
resistors. On the HED271/DPM961, 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.
2
• 200mV full scale reading
Min Typ
0.05
3
30
0
-20
3 5
7 9
2
4.5 5
8.5 9
100
Max Units
0.1 %
±1 LSD
per sec
ppm/° C
50 ° C
70 ° C
7 VDC
12 VDC
mA
5.5 VDC
9.5 VDC
40 mA
80 mA
MΩ
5 volt mode
LK5 Open
LK6 & 7 Shorted
9 volt mode
LK5 Shorted
LK6 Open