Published:2009/7/7 5:21:00 Author:May | From:SeekIC
The circuit accents two positive-voltage inputs VN and VD and provides a TTL-compatible output pulse train whose repetition rate is Proportional to the ratio VN/VD. Full-scale output frequency is about 100 Hz,and linearity error is below 0.5 percent.The output F0 equals KVN/VD,where K=1/(4R2C1)provided R1=R3. Op amp ICIA alternately integrates VN/2 and - VN/2, producing a sawtooth cutou, that ramps between the VD level and ground.When transistor Q1 is on,for example, ICIA integrates -VN/2 until its Output equals VD. At that time, the IC1B comparator switches low, causing IClD's bistable output to go low, which turns off Q1. IClA's output then ramps in the negative direction. When the output reaches 0 V,the IC1C comparator switches,Q1 turns on,and the cycle repeats.Transistor Q2 converts the IC1D output to TTL-compatibl, output logic levels. Setting VD to 1.00 V yields a reciprocal voltage-to-frequency converter(Fo=KVN),and setting VN to 1.00 V yields a reciprocal voltage-to-frequency converter(Fo=KVD).
Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/A-D_D-A_Converter_Circuit/VOLTAGE_RATIO_TO_FREQUENCY_CONVERTER.html
Print this Page | Comments | Reading(3)
Code: