digital panel modules user guide OEM22 and OEM24L (backlit) 3.5 digit LCD digital voltmeters features 3.5 Digit 12.7mm character height LCD 200mV full scale sensitivity Automatic zeroing and polarity indication Low battery indication (For 9V option only) 10 selectable annunciators Easy to use decimal point selection Display Hold as standard O ELECTRICAL CHARACTERISTICS T =25 C DESCRIPTION A CHARACTERISTIC CONDITION MIN TYP MAX UNITS The OEM22 is a neat flat pac voltmeter module that Supply voltage 9 volts 7 9 10 Volts can either be sub-panel mounted or used with the (VDD) 5 volts 4.8 5 6 Volts optional MB11 fixing bezel. The module is set up for 9 volt Supply Current 9 Volts 500 900 A operation but can be adjusted for 5V use. A low BAT (IDD) 5 Volts 5 mA annunciator is provided as standard (9Vonly). The Full scale 199.9 mV OEM24L version comes complete with a green LED backlight. All versions now come with display hold feature. Input impedance 100 M Ref voltage ROH 9 Volts 100 mV DIMENSIONS mm Overload voltage 20 Volts Zero I/P Reading 0 +1 Count Accuracy 9 volts +1 +2 Counts at FSD 5 volts +1 +4 Counts Resolution 100 V CMRR 70 dB o Temp Coefficient 100 150 ppm/ C Low Battery Ind. 9 Volts only 6.75 7.25 7.75 V Backlight Volts OEM24L 5 V Backlight Current at 5V - 40 60 mA PIN FUNCTIONS PIN DESCRIPTION VDD Positive supply terminal VSS Negative supply terminal for 9 Volt mode only INHI Positive input terminal INLO Negative input terminal RFH Reference input high terminal RFL Reference input low terminal ROH Reference output high terminal ROL Reference output low terminal HOLD Con. to VDD for display hold, to TST for normal. COM Analogue common OPERATING SPECIFICATION Connect to VDD to test all segments (except O TST annunciators), for a few seconds only. (9V mode) Operating temperature 0 to 50 C Also negative supply terminal for 5V supply. O Storage temperature -20 to 70 C XBP For driving annunciators Operating relative humidity 80% BP LCD back plane. Decimal point select. The decimal point will D1, D2, D3 energize when these pins are tied to VDD. ORDERING INFORMATION AB,B3,E3,G3, For use with external auto-ranging circuit. OEM22 3.5 digit, 200mV LCD Voltmeter o o Annunciators. See user instructions. BAT is auto BAT, C, F,~,m,,M, OEM24L 3.5 digit, 200mV LCD Voltmeter with backlight turn on. Turn it off in 5V mode by adjusting V2. ,K,V,A,HOLD MB11 Optional mounting bezel LMP + Backlight positive terminal (+5V DC) OEM24L LMP - Backlight negative terminal ( 0V DC) OEM24L Revision 8 17/011/04 USER INSTRUCTIONS CONNECTION DIAGRAM BASIC CONFIGURATION The OEM22/24L is designed for 9/5V supply. Incorrect supply polarity will destroy the module immediately. It is ready for general use when connected as in figure 1, for 9V supply. For 5V supply, the module must be calibrated before use as follows. Connect as in figure 2, apply 100mV to the inputs, from a calibrated source and adjust VR1 until the display reads 1000. The input range is 0-200mV. Over-range is indicated by blanking the three least significant digits and displaying a1 in the most significant digit. All annunciators are connected to BP for suppression For 9V operation it is recommended to power from a 9V purposes. To light up, cut the trace between the selected battery. The inputs are intended to float with respect to the annunciator pad and BP track and then link with solder supply but if they do not float they must be no closer than the annunciator pad to the XBP pad next to it. 1.5V from either VDD or VSS (VDD-1.5V and VSS+1.5V). For 5V operation, INLO must be connected to TST for See the circuits for non-floating inputs below. non-floating inputs (as fig. 2) and to the analogue common The low BAT voltage can be set adjusting VR2 but it is not pin COM for floating inputs. The low BAT annunciator recommended to operate with a supply voltage below 7V. needs to be turned of by adjusting VR2. APPLICATION CIRCUITS MULTI-RANGE DC VOLTAGE MEASUREMENT DC VOLTAGE MEASUREMENT To measure voltages greater than 200mV For multi-range, use a 2 pole, an attenuator is required. 4 way rotary switch. 1 pole for range select and the other to R1+R2 VIN=VD x VD max. is 199.99mV R2 connect the appropriate decimal point to XBP. EXAMPLES VIN Display VD R1 R2 2V 1.999V 199.9mV 1M 110K 10V 1500rpm 150mV 1M 15K The input impedance becomes R1+R2. Choose accurate stable resistors. Typically, R1=1M. 9M is a practical upper limit. MULTI-RANGE DC CURRENT MEASUREMENT DC CURRENT MEASUREMENT Vs Shunt resistance RS = For multi-range, use a 2 pole, I IN 5 way rotary switch. 1 pole for It is important to note the power range select and the other to dissipation in the shunt and choose connect the appropriate resistor rating accordingly decimal point to XBP. 2 Vs 2 PS= = IIN RS IIN EXAMPLES Current RS PS 200mA 0.04W 1 2A 0.4W 0.1 DC VOLTAGE OFFSET DC VOLTAGE RATIO MEASUREMENT To achieve a zero display reading To determine the ratio between two for a non-zero voltage input, voltages apply the inputs as shown. apply the offset voltage between COM and INLO. V2 Displayed reading = X 1000 V1 For a positive offset apply a Positive signal to INLO w.r.t. COM. V2 Over range occurs when > 2 Apply the input signal between V1 INHI and COM. NON FLOATING INPUTS (b) NON FLOATING INPUTS (a) Using the formulae choose resistors to Where a single 5V supply is not ensure the analogue inputs are no suitable but you must connect your closer than 1.5V from either VDD or input signal ground to the module VSS (VDD-1.5V or VSS+1.5V) supply ground, then either of these two non-floating input circuits can be used. Note that the module is set in the 9V supply mode. Revision 8 17/011/04 anders electronics plc Bayham Place, London NW1 OEU UK Tel: +44 (0)20 7380 8167 Fax: +44 (0)20 7874 1908