TB2905HQ Toshiba, TB2905HQ Datasheet - Page 7

• Manufacturer Part Number: TB2905HQ
• Manufacturer: Toshiba

Specifications of TB2905HQ

• No. Of Channels: 4
• Package: HZIP 25-P-1.00F
• Recommended Vcc (v): 13.2
• Rl=2 Ohm: 80W x 4
• Rl=4 Ohm: 50W x 4
• Rl=8 Ohm: -
• Features/built-in Functions: 4 BTL channels, standby switch, mute, BiCD process, Class-KB high efficiency
• Operating Voltage (v): 9 to 18

6. Pop Noise Suppression
7. External Component Constants
8. Preventive measure against oscillation
Component
Name
C1
C2
C3
C4
C5
C6
input capacitance C1 to AC-GND capacitance C6 be 1:4.
and C6 completes, the input DC balance becomes unbalanced, causing a pop noise to be produced.
C6. Note that the time which audio output takes to start will be longer, since C2 determines the muting
time (the time from when the power is turned on to when audio output starts).
time constant for C4.
signal is applied to C4 to when the muting function is turned on/off will be longer.
under all the necessary condition.
according to the causes described below,
1) Layout of printed board
2) Type of Speaker
3) Value and kind of the capacitor between the output(+) and output(-)
4) Value and kind of the CR filter or the capacitor between each output and GND.
For preventing the oscillation, check that the application circuit and actual load makes no abnormal oscillation
Especially, perform the temperature test to check the oscillation margin since the oscillation margin is varied
The TB2905HQ uses AC-GND as a common NF pin for all amplifiers, thus requiring that the ratio of
Powering up the IC initiates the charging of C1 and C6. If the IC is turned off before the charging of C1
To suppress the noise, it is recommended that a longer charging time be used for C2 as well as for C1 and
The pop noise which is generated when the muting function is turned on/off will vary according to the
The greater the capacitance, the lower the pop noise. Note that the time from when the muting control
Recommended
3900 µF
0.22 µF
0.1 µF
Value
10 µF
1 µF
1 µF
oscillation margin
NF for all outputs
To reduce ripple
To eliminate DC
To reduce pop
Ripple filter
To provide
sufficient
Purpose
noise
Cutoff frequency is increased
Duration until muting function
Smaller than Recommended
Reduces noise and provides sufficient oscillation margin
Powering on/off is faster
is turned on/off is short
High pop noise
Pop noise is suppressed when C1:C6 = 1:4
Power supply humming and ripple filtering
7
Value
Effect
Duration until muting function
Larger than Recommended
Cutoff frequency is reduced
Powering on/off is slower
is turned on/off is long
Low pop noise
Value
TB2905HQ
Affects the pop
noise
generated
when VCC is
turned on
2005-08-17
Affects the pop
when VCC is
generated
turned on
Remarks
noise