digital panel modules user guide OEM335A 3.5 digit LED voltmeter module features Bright, red LED display Single 5V DC operation. 10.16mm digit height Decimal point selectable Self mountable. Single ended or differential input. O DESCRIPTION ELECTRICAL CHARACTERISTICS T =25 C A CHARACTERISTIC MIN TYP MAX UNIT The OEM335A is a complete digital voltmeter module in a Power supply Voltage 4.75 5 5.25 V very compact package incorporating a dual-slope Power Supply Current 180 mA analogue to digital converter, a 100mV reference with Sampling Rate 2.5 Reading/sec. 200mV full scale input sensitivity. The large sized LED makes the module easily readable Accuracy 0.1 1 % digits from distance away. Auto-zeroing is provided by the Input Impedance 100 M circuit itself, so no zero adjustment is required. The Input leakage Current 1 10 PA module also has input polarity and over-range indication. o Temperature Coefficient 100 PPM/ C DIMENSIONS mm PIN FUNCTIONS PIN SYMBOL DESCRIPTION 1 V+ +5V Power supply. 2 GND Ground (0V for power supply). 3 IN HI Signal input terminals. If potential on INHI is 4 IN LO lower than INLO, display will show negative. 5DP1 Decimal point select. The decimal point will be 6DP2 shown if connected to DP.com and will be off if kept floating. 7DP3 8 DP.com Decimal point return PANEL CUT OUT OPERATING SPECIFICATION Operating voltage 5V DC + 5% O Operating temperature 0 to 50 C O Storage temperature -10 to 70 C Relative humidity 80% MODULE VIEW FROM REAR ORDERING INFORMATION OEM335A 3.5 Digit, 200mV LCD voltmeter module LM201 Connector and cable OEM335AV4 Revision 4 - 21/10/03 USER INSTRUCTIONS CONNECTION DIAGRAM BASIC CONFIGURATION The OEM335A is designed for +5V single rail supply. Incorrect supply will damage the module. Apply the input signal between pin 3 (INHI) and pin 4 (INLO). The input range is 0 - 199.9mV. Over range is indicated by illuminating a1 in the most significant digit and blanking the other digits. It is recommended to use this module with floating inputs i.e. the low input signal (INLO) must be isolated from the power supply ground (GND). Where (INLO) must be referenced to the power supply, connect via a 10K resistor and a 0.1F capacitor as shown opposite. To activate a decimal point, connect the appropriate decimal point pin to DPcom. APPLICATION CIRCUITS DC VOLTAGE MEASUREMENT MULTI-RANGE 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 V+ 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. DC CURRENT MEASUREMENT DC MULTI-RANGE 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 V+ 2 Vs 2 PS = = IIN RS I IN EXAMPLES Current RS PS 200mA 0.04W 1 2A 0.1 0.4W AC VOLTAGE MEASUREMENT The meter can only measure DC. Use the above circuit to convert AC to DC. For voltages above 200mV AC, a potential divider is required before the converter circuit as shown in theVoltage measuremen section above OEM335AV4 Revision 4 - 21/10/03 anders electronics plc Bayham Place, London NW1 OEU UK Tel: +44 (0)20 7380 8167 Fax: +44 (0)20 7874 1908 www.anders.co.uk