STK4172II Sanyo, STK4172II Datasheet - Page 6

• Manufacturer Part Number: STK4172II
• Description: AF Power Amplifier
• Manufacturer: Sanyo

Description of External Parts
(R12, R14)
(R6, R10)
C11, C12
R11, R13
R19, R20
R15, R16
C9, C10
C1, C2
C3, C4
C5, C6
R3, R4
R1, R2
R5, R9
C15
C14
R21
R18
C7
Input filter capacitors
• A filter formed with R3 or R4 can be used to reduce noise at high frequencies.
Input coupling capacitors
• Used to block DC current. When the reactance of the capacitor increases at low frequencies, the dependence of 1/f noise on signal source
• To reduce the pop noise at the time of application of power, it is effective to increase C3, C4 that fix the time constant on the input side and
NF capacitors
• These capacitors fix the low cutoff frequency as shown below.
Decoupling capacitor
• Used to eliminate the ripple components that mix into the input side from the power line (+V
Bootstrap capacitors
• When the capacitor value is decreased, the distortion is liable to be higher at low frequencies.
Oscillation blocking capacitors
• Must be inserted as close to the IC power supply pins as possible so that the power supply impedance is decreased to operate the IC stably.
• Electrolytic capacitors are recommended for C9, C10.
Capacitor for ripple filter
• Capacitor for the TR10-used ripple filter in the IC system
Oscillation blocking capacitor
• A polyester film capacitor, being excellent in temperature characteristic, frequency characteristic, is recommended for C7.
Resistors for input filter
Input bias resistors
• Used to bias the input pin potential to zero. These resistors fix the input impedance practically.
These resistors fix voltage gain VG.
It is recommended to use R5 (R6) = 560 , R9 (R10) = 56k for VG = 40dB.
• To adjust VG, it is desirable to change R5 (or R6).
• When R5 (or R6) is changed to adjust VG, R1 (=R2) =R9 (=R10) must be set to ensure V
Bootstrap resistors
• The quiescent current is set by these resistors 3.3k + 3.3k . It is recommended to use this resistor value.
Resistor for ripple filter
• (Limiting resistor for predriver transistor at the time of load short)
Used to ensure plus/minus balance at the time of clip.
Resistor for ripple filter
• When muting TR11 is turned ON, current flows from ground to -V
Oscillation blocking resistors
resistance causes the output noise to worsen. It is better to decrease the reactance.
to decrease C5, C6 on the NF side.
To provide the desired voltage gain at low frequencies, it is better to increase C5. However, do not increase C5 more than needed because
the pop noise level becomes higher at the time of application of power.
allowing for the power that may be dissipated on that occasion.
f
L
=
--------------------------
2
C5 R5
1
[Hz]
STK4172 II
CC
through TR 11. It is recommended to use 1k (1W) + 1k (1W)
N
balance.
CC
).
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