The OEM33 (also known as the VK1000) is one of the
world's smallest digital voltmeters. It is an ideal
replacement for analogue meters with advantages of
accuracy, size and easy mounting. The module includes
an A/D converter, LCD display of 10mm character height,
and plastic housing with standard dual in line pin
terminals for easy insertion into sockets or PC Board.
DESCRIPTION
Operating temperature 0 to 50OC
Storage temperature -20 to 70OC
Operating relative humidity 80%
OPERATING SPECIFICATION
ORDERING INFORMATION
DIMENSIONS mm
features
Revision - 8 22/06/00 @@FBCREATE 0001, OEM33/H Data Sheet@@
OEM33 & OEM33H 3.5 di
g
it LCD di
g
ital voltmeter
3.5 Digit 10mm character height LCD
200mV Full Scale sensitivity
Automatic zeroing and polarity indication
11 selectable annunciators
Easy to use decimal point selection
Built in snap fastener
Display on hold option OEM33H
Panel cut out 40.5 x 22.5
Fastening clips accept panel thickness 0.9 to 3.2mm
This module is a version of the OEM33 featuring a digital
display hold facility. For normal, continuous operation
connect the 'Hold 1' pin to the GD pin. To hold the present
reading, connect 'Hold 1' to VDD. Do not leave this pin
floating or it will drift in and out of hold mode.
OEM33H - VERSION WITH DISPLAY HOLD FACILITY
OEM33 3.5 digit, 200mV LCD Voltmeter
OEM33H 3.5 digit, 200mV LCD with display hold
CHARACTERISTIC CONDITION MIN TYP MAX UNITS
Supply voltage (VDD) 9 Volts
5 Volts 7
4.5 9
510
6V
V
Supply Current (IDD) 9 Volts
5 Volts 100
2500
3µA
mA
Full scale 199.9 mV
Input Impedance 100 MΩ
Reference Voltage 9 Volts 100 mV
Overload voltage 20 V
Zero I/P Reading 0 +1 Counts
Accuracy
at FSD 9 Volts
5 Volts +2
+2 +4
+4 Counts
Counts
Linearity 9 Volts
5 Volts +1
+1 +2
+2 Counts
Counts
Resolution 100 µV
CMRR 70 dB
Temp Coefficient 100 150 ppm/ oC
ELECTRICAL CHARACTERISTICS TA=25OC¡
VDD Positive supply terminal
VSS Negative supply terminal for 9 volts operation
GD Negative supply terminal for 5 volts operation
IH Input high terminal
IL Input low terminal
RH Reference high input terminal
RL Reference low input terminal
HOLD1 Connect to VDD for hold and GD for continuous
C Analogue Common
XBP For driving annunciator
BP LCD back plane
D1, D2, D3 Decimal point pins . D1 = .000, D2 = 0.00 D3 = 00.0
The decimal point will appear if the corresponding
terminal is connected to XBP.
BAT, oC, oF,~,
m, µ, MΩ, KΩ,
V, A, HOLD2 Annunciators
PIN FUNCTIONS
All annunciators not in use must be connected to the BP
pin for suppression purposes. To light up an annunciator,
connect the corresponding pin to XBP.
di
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ital panel modules user
g
uide
DQGHUV
HOHFWURQLFV SOF
Bayham Place, London NW1 OEU UK
Tel: +44
(
0
)
20 7380 8167 Fax: +44
(
0
)
20 7874 1908 http://www.meters.anders.co.uk
For 9V operation it is recommended to power from a 9V
battery. The inputs are intended to float with respect to
the supply but if they do not float they must be no closer
than 1.5V from either VDD or VSS (VDD-1.5V and
VSS+1.5V)
see the circuits for non-floating inputs below.
CONNECTION DIAGRAM BASIC CONFIGURATION
APPLICATION CIRCUITS
To measure voltages greater than 200mV an
attenuator is required.
VIN=VD x R1+R2 VD max. is 199.99mV
EXAMPLES
VIN Display VDR1 R2
2V 1.999V 199.9mV 1MΩ110KΩ
10V 1500rpm 150mV 1MΩ15KΩ
R2
The input impedance becomes R1+R2. Choose accurate stable resistors.
Typically, R1=1MΩ. 9MΩ is a practical upper limit.
DC MULTI-RANGE VOLTAGE MEASUREMENT
DC CURRENT MEASUREMENT
Shunt resistance RS = Vs Ω
It is important to note the power
dissipation in the shunt and choose
resistor rating accordingly
PS= Vs = IIN RS Ω
EXAMPLES
22
IIN
IIN
Current RSPS
200mV 1Ω0.04W
2A 0.1Ω0.4W
DC MULTI-RANGE CURRENT MEASUREMENT
For multi-range, use, a 2 pole, 5
way rotary switch. 1 pole for
range select and the other to
connect the appropriate
decimal point to XBP
DC VOLTAGE RATIO MEASUREMENT
To determine the ratio between two
voltages apply the inputs as shown.
Displayed reading = V2 X 1000
Over range occurs when V2 > 2
Note Jumper J1 must be closed
V1
V1
To achieve a zero display reading
for a non-zero voltage input, apply
the offset voltage between C and
IL.
For a positive offset apply a
Positive signal to IL w.r.t. C.
Apply the input signal between IH
and C
Note jumper J1 must be open
DC VOLTAGE OFFSET
The OEM33 is designed for 5/9V supply. Incorrect supply
polarity will destroy the module immediately. It is ready
for general use when connected as in fig 1 for 5 volts.
For 9 volt supply the module may need calibrating before
use as follows. Connect as in fig. 2, apply 100mV to the
inputs from a calibrated source and adjust VR1 until the
display reads 1000.
The input range is 0-199.9mV . Over-range is indicated
by blanking the three least significant digits and
displaying a "1" in the most significant digit. If the input
voltage is reversed, a minus sign is displayed
automatically.
The module has 3 decimal points. D1, D2, D3 and 11
selectable annnunciators.
For 5V operation, IL must be connected to GD for
non-floating inputs (as fig. 1) and to the analogue
USER INSTRUCTIONS
Where a single 5V supply is not suitable
but you must connect your input signal
ground to the module supply ground
then either of the two non-floating input
circuits can be used. Note that the
module is set in 9V supply mode BUT
jumper J1 is left open.
NON FLOATING INPUTS (a) NON FLOATING INPUTS (b)Using the formulae choose resistors to
ensure the analogue inputs are no closer
than 1.5V from either VDD or VSS
(VDD-1.5V or VSS+1.5V)
For multi-range, use a 2 pole, 4
wa y rotary switch. 1 pole for
range select and the other to
connect the appropriate
decimal point to XBP.
DC VOLTAGE MEASUREMENT
