LA75676V_07 Datasheet, PDF (8/9 Pages) Sanyo Semicon Device – For TV and VCR Products IF Signal Processor (VIF+SIF)

LA75676V
V21, V22. VIF input resistance, input capacitance • • • • [Ri, Ci]
1. Use an impedance analyzer to measure Ri and Ci in the input impedance test circuit.
V23, V24. APC pull-in range • • • • [fpu, fpl]
1. Internal AGC
2. fp = 39MHz to 51MHz, CW : 10mVrms
3. Vary the signal generator from fp = 45.75MHz towards higher frequencies until PLL lock is lost.
Note : PLL lock is lost at the point beating is output at test point A.
4. Lower the signal generator frequency until the PLL locks again. (f1)
5. Lower the signal generator frequency until PLL lock is lost.
6. Raise the signal generator frequency until the PLL locks again. (f2)
7. Perform the following calculations.
fpu = f1 - 45.75MHz
fpl = f2 - 45.75MHz
V25. AFT tolerance frequency 1 • • • • [∆Fa1]
1. Internal AGC
2. SG1 : Vary this frequency from 43.75MHz to 47.75MHz, CW, 10mVrms
3. Vary the SG1 frequency so that the AFT output (test point B) becomes 2.5V.
Record the SG1 frequency at that point as f1.
4. External AGC (Adjust V17.)
5. Apply 5V to the IF AGC (pin 17), pick up the VCO oscillator frequency from ground or some other point, and
measure that frequency. f2
6. Perform the following calculation.
AFT tolerance frequency 1 ∆Fa1 = f2 - f1 (kHz)
V26, V27. VCO maximum range (U, L) • • • • [dfu, dfl]
1. External AGC. Apply the VCC voltage to the IF AGC (pin 17).
2. Pick up the VCO oscillator frequency from the video output (A), ground, or some other point and adjust the VCO
coil so that frequency becomes 45.75MHz.
3. Apply 1V to the APC pin (pin 9) and let fl be the frequency at that time.
Similarly, apply 5V and let fu be the frequency at that time.
dfu = fu - 45.75MHz
dfl = fl - 45.75MHz
V28. VCO control sensitivity • • • • [β]
1. External AGC. Apply the VCC voltage to the IF AGC (pin 17).
2. Pick up the VCO oscillator frequency from the video output (A), ground, or some other point and adjust the VCO
coil so that frequency becomes 45.75MHz.
3. Apply 3V to the APC pin (pin 9) and let f1 be the frequency at that time.
Similarly, apply 3.4V and let f2 be the frequency at that time.
β
=
f2 - f1
400
(kHz/mV)
S1. SIF limiting sensitivity • • • • [Vi (lim)]
1. External AGC. Apply the VCC voltage to the IF AGC (pin 17).
2. fs = 4.5MHz, fm = 400Hz, ∆F = ±25kHz (SIF input)
3. Set the SIF input level to 100mVrms and measure the value at test point D at that time. • • V1
4. Lower the SIF input level and measure the input level such that V1 is down by 3dB.
S2, S4. FM detection output voltage, total harmonic distortion • • • • [VO(FM), THD]
1. External AGC. Apply the VCC voltage to the IF AGC (pin 17).
2. fs = 4.5MHz, fm = 400Hz, ∆F = ±25kHz (SIF input, Vi = 100mVrms)
3. Measure the FM detection output voltage and total harmonic distortion at test point D.
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