EID's Instrument Digital Snap-in 3.5 digits panel voltmeter:

 

Features:

 

3 1/2 digit, 9.5 mm character height display

200mV full-scale input sensitivity (0-2000mV option)

10 pA input current typical

Automatic polarity

Easy panel mounting

14 analytical icons on display

Easy to use decimal point and icons

9V or 5V operation

Reflective mode

 

Specifications, Electrical Characteristics - Ta=+25C

  • Supply Voltage (VDD=9V)             Min 7V    Typ. 9V  Max 10V  

  • Supply Voltage (VDD=5V)             Min 4.5V Typ. 5V  Max 6V  

  • Supply Current (IDD) for 9V          Typ. 100uA Max 500uA  

  • Supply Current (IDD) for 5V          Typ. 2mA  Max 3mA  

  • Leakage Input Current                 TYp. 1pA  Max 10pA

  • Reference Voltage
    (Factory Adjusted)
                          100mV For 9 volts option only

  • Full Scale                                   Max 200mV  

  • Zero Input Reading                      Typ. +/-0.000 Count

  • Accuracy for 9V
    (Input at 199.5 mV)
                         Typ. +/-2 Count Max +/-4 Count

  • Accuracy for 5V
    (Input at 199.5 mV)
                         Typ. +/-2 Count +/-4 Count

  • Operating temperature                  0 - 50 [C], 32 - 122 [F]

  • Storage temperature                    -40C to +70C

  • Operating relative humidity            90% Max

  • Linearity                                    Typ. +/-1
    (Max deviation from best straight line)

  • Resolution                                  Typ. 100uV

  • Sampling rate                             Typ. 3 Read/Sec Max 4 Read/Sec

  • CMRR                                        Typ. 70dB

  • Temp coefficient                         Typ. 100ppm/C Max 150ppm/C

  • Standard Annunciators (Icons)       m, u, V, S/cm, ALERT, BATT, K, C, F, RPM, pH, ATC, %RH & EID Corp

Drawings

 

Applications notes:

Over & Under range Signal

Overrange-Underrange signal

 

The additional IC's which are required to generate the over range and under range signal.
The respective terminals are accessible to the module.

 

Zero Display for Non-Zero Input Voltage

Zero Display for Non-Zero Input Voltage

 

If a zero display is required when the input voltage level is not zero, the offset voltage should be connected between INLO and COM, while the input voltage is connected between COM and INHI.

 

Over range & Under range Signal

 

Overrange-Underrange signal

 

A simple temperature sensor is an ordinary silicon diode or the base emitter of a silicon transistor. The forward voltage of a typical silicon PN junction change is -2.1mV/C. Since the sign of the voltage change is negative, the diode voltage is applied to INLO to give correct polarity. R1 offsets the forward voltage drop of about 550mV causing the display to read 0.00 at 0C. R2 adjusts the reference to match the slope of the diode voltage versus temperature. Ideally the sensor diode should be driven by a current source. Substituting a high value resistor will only add approximately 0.75C of non-linearity. The resistor also slightly compensates for the reference temperature drift and decreasing battery voltage. To calibrate the circle, the diode sensor must first be immersed in a stirred ice water bath (0C) and adjust R1 to 0.00 reading. Then immerse the diode in boiling water and adjust R2 to 100.0 reading.

 

Non-Floating Supply

 

Non-floating supply


Figure (a)


Where VDD-VSS<15V
Either INHI or INLO has to be connected to ground

 

Non-floating supply


Figure (b)

 

 

VIN(MAX)(R2)

200mV

-------------------

R1+R2-R3

 

VIN(MAX)(R2-R3)

VDD-1.5V

-------------------

R1+R2+R3


 

VIN(MIN)(R3)

VDD+1.5V

-------------------

R1+R2-R3

 

 

Diagnostic flow diagram

 

Figure (c)

 

A 9V battery is recommended for 9V operation. It is intended that the analog inputs (INHI / INLO) float with respect to the 9V supply. Please note, if a non-floating supply is required, some care must be taken. (Refer to the data sheet "200mV digital voltmeter" circuit). In general, if the analog inputs do not float with respect to the supply, the analog input must be no closer than 1.5V from either supply voltage (VDD / VSS). This can be done by using a (a) split. The flow chart in figure (c) will help to guide you to the proper solution.

 

Input Attenuators

 

Input attenuator

 

To measure voltage greater than 200mV, an input attenuator is needed
The Full Scale Sensitivity is given by

 

 

VIN (F.S.) =

1.999 x VREF x

R1+R2

(V)REF = 0.1V

----------

R2

 

R1 + R2 should be accurate and stable. Good metal film resistor meet these requirements. The input attenuator reduces the input resistance of the circuit from >10 ohms to R1+R2. A practical upper limit is 9M for R1.

 

 

 

In multi-range applications it is necessary to also witch the decimal point. This can easily be accomplished by connecting the appropriate D1 to D3 terminal with a rotary switch to XBP pin ( D1=.000, D2=0.00, D3=00.0 

 

20mV Full Scale

Input attenuator

 

An operational amplifier is used to measure full scale voltages less than 199.9mV. Note that the auto zero circuitry within the module cannot compensate for the op-amp offset or voltage drift.

 

AC Voltage Measurements

 

The module can only measure DC
To measure AC voltage, an AC to DC converter needs to be used to condition the waveform.

 

Current Measurements

 

The use of a shunt resistor converts the current to a voltage. The following formula can be used to calculate the shunt resistor.

 

Display reading =

Iin x Rs

x 1000 VREF = 0.1V
Iin x Rs = 0.2V (full scale)

-----------

VREF

 

A multi-range current meter circuit is shown. Note that although the input current passes through the selector switch, the voltage drop across the switch does not contribute to the measured voltage.

 

Resistance Measurements

 

 

The radiometric technique is used for resistance measurements. The unknown resistance is placed in series with a known resistor and current is passed through the pair. The voltage developed across the unknown resistor applied to the input (INHI, INLO). The voltage across the known resistor applied to reference inputs REH and REI. If the unknown equals the standard, the display will read 1000.

 

Display reading =

Iin x Rs

x 1000 VREF = 0.1V

-----------

VREF

 

Due to the radiometric technique, no accurately defined reference voltage is required. The module will over-range for R unknown 2xR standard.

 

Pricing 

 

* Prices and product/sensor/cable colors are subject to change without notice. 

   Additional 10% discount with student ID, USA only.

Description and SKU#

Price 1-10

10-100

100-1K

Picture

DVM 3.5 digits panel voltmeter 9V

EID-D-LCD-35-200-9V (Old P#)

new P# EID-DSP-LCD35-A001-9V

 

19.75

 

14.95

 

9.95