NTE890 Integrated Circuit Voltage to Frequency Converter Description: The NTE890 is an integrated circuit in an 8–Lead DIP type package and provides a simple method of A/D conversion. It has all the inherent advantages of the voltage–to–frequency conversion technique. The output is a series of constant duration pulses. The frequency of the pulses is proportional to the applied input voltage. This converter is designed for use in a wide range of data conversion and remote sensing applications. Absolute Maximum Ratings: (TA = +25°C unless otherwise specified) Supply Voltage, V+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8V to 22V Output Sink Current, ISINK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA Power Dissipation, PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500mW Input Voltage, Vi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.2V to V+(V) Operating Temperature Range, Topr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –20° to +75°C Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40° to +125°C Electrical Characteristics: (V+ = +15V, TA = +25°C unless otherwise specified) Parameter Min Typ Max Unit 8V < V+ < 15V 2.0 3.5 6.0 mA 15V < V+ < 22V 2.0 4.5 7.5 mA Conversion Accuracy Scale Factor VIN = 10V, RS = 14kΩ 0.9 1.0 1.1 kHz/V Drift with Temperature VIN = 10V – ±100 – ppM/°C Drift with V+ VIN = 1V, 8V < V+ < 18V – 0.2 1.0 %/V – 5 10 mV Offset Current – ±50 ±100 nA Input Bias Current – –100 –300 nA – V Supply Current Test Conditions Input Comparator Offset Voltage Common Mode Range One–Shot Threshold Voltage Note 1 0 to V+ –3 0 to V+ –2 Pin5 0.63 0.66 0.70 x V+ Input Bias Current Pin5 – –100 –500 nA Reset VSAT Pin5, I = 2.2mA – 0.15 0.50 V Note 1 Input Common Mode Range includes GND. Electrical Characteristics (Cont’d): (V+ = +15V, TA = +25°C unless otherwise specified) Parameter Min Typ Max Unit RS = 14kΩ, Pin1, V+ = 0V – 138.7 – µA Change with Voltage Pin1, V+ = 0V to 10V – 1.0 2.5 µA Off Leakage Pin1, V+ = 0V – 1 50 nA Reference Voltage Pin2 1.70 1.90 2.08 V Pin3, I = 3mA – 0.15 0.50 V Pin3, I = 2mA – 0.10 0.30 V – 0.1 1.0 µA Current Source Output Current Logic Output VSAT VSAT Test Conditions Off Leakage Note 2. The voltage applied to comparator input Pin6 and Pin7 should not be allowed to go below GND by more than 300mV. Note 3. Pin3 and Pin5 are open–collector outputs. Shorts between these pins and V+ can cause overheating and eventual destruction. Note 4. Reference voltage terminal Pin2 is connected to the emitter of an NPN transistor and is held at approximately 1.9V. This terminal should be protected from accidental shorts to GND or supply voltages. Permanent damage may occur if current in Pin2 exceeds 5mA. Note 5. Avoid stray coupling between Pin5 and Pin7 which could cause false triggering. If false triggering is experienced with the precision mode circuits, bypass Pin6 to GND with at least 0.01µF. This is necessary for operation above 10kHz. Pin Connection Diagram 8 VCC Current Source 1 Scale Factor 2 7 Input Voltage Logic Output 3 6 Threshold GND 4 8 5 One–Shot R, C 5 .260 (6.6) 1 4 .390 (9.9) Max .300 (7.62) .155 (3.93) .100 (2.54) .145 (3.68) .300 (7.62)