NTE890 Integrated Circuit Voltage to Frequency Converter Description: The NTE890 is an integrated circuit in an 8Lead DIP type package and provides a simple method of A/D conversion. It has all the inherent advantages of the voltagetofrequency conversion tech- nique. 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: (T = +25C unless otherwise specified) A Supply Voltage, V+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8V to 22V Output Sink Current, I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA SINK Power Dissipation, P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500mW D Input Voltage, V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2V to V+(V) i Operating Temperature Range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 to +75C opr Storage Temperature Range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 to +125C stg Electrical Characteristics: (V+ = +15V, T = +25C unless otherwise specified) A Parameter Test Conditions Min Typ Max Unit Supply Current 8V < V+ < 15V 2.0 3.5 6.0 mA 15V < V+ < 22V 2.0 4.5 7.5 mA Conversion Accuracy Scale Factor V = 10V, R = 14k 0.9 1.0 1.1 kHz/V IN S Drift with Temperature V = 10V 100 ppM/C IN Drift with V+ V = 1V, 8V < V+ < 18V 0.2 1.0 %/V IN Input Comparator Offset Voltage 5 10 mV Offset Current 50 100 nA Input Bias Current 100 300 nA Common Mode Range Note 1 0 to V+ 3 0 to V+ 2 V OneShot Threshold Voltage Pin5 0.63 0.66 0.70 x V+ Input Bias Current Pin5 100 500 nA Reset V Pin5, I = 2.2mA 0.15 0.50 V SAT Note 1 Input Common Mode Range includes GND.Electrical Characteristics (Contd): (V+ = +15V, T = +25C unless otherwise specified) A Parameter Test Conditions Min Typ Max Unit Current Source Output Current R = 14k , Pin1, V+ = 0V 138.7 A S Change with Voltage Pin1, V+ = 0V to 10V 1.0 2.5 A Off Leakage Pin1, V+ = 0V 1 50 nA Reference Voltage Pin2 1.70 1.90 2.08 V Logic Output V Pin3, I = 3mA 0.15 0.50 V SAT V Pin3, I = 2mA 0.10 0.30 V SAT Off Leakage 0.1 1.0 A 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 opencollector 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 trig- gering is experienced with the precision mode circuits, bypass Pin6 to GND with at least 0.01 F. This is necessary for operation above 10kHz. Pin Connection Diagram Current Source 1 8 V CC Scale Factor 2 7 Input Voltage Logic Output 3 6 Threshold GND 4 5 OneShot R, C 85 .260 (6.6) 14 .390 (9.9) .300 Max (7.62) .155 (3.93) .100 (2.54) .145 (3.68) .300 (7.62)