Datasheet ADVFC32 (Analog Devices) - 7

ADVFC32
C00443c–0–11/00 (rev. B) Figure 6. High Noise Immunity Data Link The data link input voltage is changed in a frequency modulated Although the F/V conversion technique used in this circuit is signal by the first ADVFC32. A 42.2 kΩ input resistor and a quite simple, it is also very limited in terms of its frequency 100 kΩ offset resistor set the scaling so that a 0 V input signal response and output ripple. The frequency response is limited corresponds to 50 kHz, and a 10 V input results in the maximum by the integrator time constant and while it is possible to decrease output frequency of 500 kHz. A high frequency optocoupler is that time constant, either signal range or output ripple must be then used to transmit the signal across any common-mode volt- sacrificed. The performance of the circuit of Figure 6 is shown age potentials to the receiving ADVFC32. The optocoupler is in the photograph below. The top trace is the input signal, the not necessary in systems where common-mode noise is either middle trace is the frequency-modulated signal at the opto- very small or a constant low level dc voltage. In systems where coupler’s output, and the bottom trace is the recovered signal at common-mode voltage may present a problem, the connection the output of the F/V converter. between the two locations should be through the optocoupler; no power or ground connections need to be made. The output of the optocoupler drives an ADVFC32 hooked up in the F/V configuration. Since the reconstructed signal at Pin 10 has a considerable amount of carrier feedthrough, it is desir- able to filter out any frequencies in the carrier range of 50 kHz to 500 kHz. The frequency response of the F/V converter is only 3 kHz due to the pole made by the integrator, so a second 3 kHz filter will not significantly limit the bandwidth. With the simple one pole filter shown in Figure 6, the input to output 3 dB point is approximately 2 kHz, and the output noise is less than 15 mV. If a lower output impedance drive is needed, a two-pole active filter is recommended as an output stage.
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
TO-100 (H-10A) 14-Lead Plastic DIP (N-14) 0.795 (20.19) REFERENCE PLANE 0.725 (18.42) 0.750 (19.05)
PRINTED IN U.S.A.
0.500 (12.70) 0.185 (4.70) 0.160 (4.06) 14 8 0.280 (7.11) 0.165 (4.19) 0.250 (6.35) MIN 0.110 (2.79) 0.050 (1.27) MAX 1 7 0.240 (6.10) 0.325 (8.25) 6 PIN 1 7 0.100 (2.54) 0.300 (7.62) 5 0.060 (1.52) 8 0.045 (1.14) BSC 0.115 4 0.015 (0.38) (2.92) 0.027 (0.69) 0.210 (5.33) 0.195 (4.95) BSC 9 MAX 0.130 0.115 (2.93) 0.370 (9.40) 0.335 (8.51) 0.335 (8.51) 0.305 (7.75) 3 10 0.160 (4.06) (3.30) 2 1 0.034 (0.86) MIN 0.019 (0.48) 0.027 (0.69) 0.115 (2.93) 0.015 (0.381) 0.230 (5.84) 0.016 (0.41) SEATING BSC 0.022 (0.558) 0.070 (1.77) 0.008 (0.204) 0.040 (1.02) MAX 36° BSC PLANE 0.021 (0.53) 0.014 (0.356) 0.045 (1.15) 0.045 (1.14) 0.016 (0.41) 0.010 (0.25) BASE & SEATING PLANE
–6– REV. B