MB86437 Datasheet, PDF (13/35 Pages) Fujitsu Component Limited. – 3 V Single Power Supply Audio Interface Unit (AIU)

MB86437
• Tone envelope
Even if the tone halts at close to zero, changes in the DC voltage can still occur can be audible. Using SW16 for
tone control enables the voltage level for tone generation to be controlled. The waveform amplitude characteristics
have the following general relationships.
Va = 2 × (0.47 – 0.12 × Vl) (Vl: MDI voltage, Va = Tone amplitude)
Control clock
R5
V1
R 4 _C1
210 kΩ SW 16
MDI 130 kΩ 25 kΩ
VR
–
+
AMP 3
SGC
Tone
output
MDI
Vl Vh
For a cut off frequency of 8.3 Hz, control clock of 0 to 3 V, and SGC = 1.5 V, the envelope ratio and resistor and
capacitor values are as follows.
Envelope Ratio
Aim Value
–3 dB
–4 dB
–5 dB
–6 dB
Recommended Values
R4
R5
C1
33 kΩ
22 kΩ
1.5 µF
47 kΩ
18 kΩ
1.5 µF
82 kΩ
15 kΩ
1.5 µF
270 kΩ
15 kΩ
1.5 µF
Vh, Vl Voltages
Max. (Vh) Min. (Vl)
0.828 V
0.584 V
0.824 V
0.516 V
0.810 V
0.448 V
0.790 V
0.400 V
Envelope Ratio
Calculated Value
–3.13 dB
–4.05 dB
–5.15 dB
–5.91 dB
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