TB2904 데이터 시트보기 (PDF) - Toshiba
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TB2904 Datasheet PDF : 16 Pages
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TB2904HQ(o)
6. Pop Noise Suppression
Since the AC-GND pin (pin 16) is used as the NF pin for all amps, the ratio between the input
capacitance (C1) and the AC-to-GND capacitance (C6) should be 1:4.
Also, if the power is turned OFF before the C1 and C6 batteries have been completely charged, pop noise
will be generated because of the DC input unbalance.
To counteract the noise, it is recommended that a longer charging time be used for C2 as well as for C1
and C6. Note that the time which audio output takes to start will be longer, since the C2 makes the muting
time (the time from when the power is turned ON to when audio output starts) is fix.
The pop noise which is generated when the muting function is turned ON/OFF will vary according to the
time constant of C4.
The greater the capacitance, the lower the pop noise. Note that the time from when the mute control
signal is applied to C4 to when the muting function is turned ON/OFF will be longer.
7. External Component Constants
Component Recommended
Name
Value
Purpose
Effect
Lower than recommended
value
Higher than recommended
value
Notes
C1
0.22 µF
To eliminate DC
Cut-off frequency is
increased
Pop noise is
Cut-off frequency is reduced generated when
VCC is ON
C2
10 µF
To reduce ripple
Powering ON/OFF is faster
Powering ON/OFF takes
longer
To provide
C3
0.1 µF
sufficient
Reduces noise and provides sufficient oscillation margin
oscillation margin
C4
1 µF
To reduce pop
noise
High pop noise. Duration until Low pop noise. Duration until
muting function is turned
muting function is turned
ON/OFF is short
ON/OFF is long
C5
3900 µF Ripple filter
Power supply ripple filtering
C6
1 µF
NF for all outputs Pop noise is suppressed when C1:C6 = 1:4
Pop noise is
generated when
VCC is ON
Note: If recommended value is not used.
7
2004-03-26
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