TA8258HQ
TOSHIBA Bipolar Linear Integrated
Circuit Silicon Monolithic
TA8258HQ
Dual Audio Power Amplifier
The TA8258HQ is dual audio power amplifier for consumer
applications.
This IC provides an output power of 20 watts per channel
(at V
CC
= 37 V, f = 1kHz, THD = 10%, R
L
= 8
Ω).
It is suitable for power amplifier of music center.
Features
•
•
•
•
•
•
•
•
High output power: P
out
= 20 W/channel (Typ.)
(V
CC
= 37 V, R
L
= 8
Ω,
f = 1 kHz, THD = 10%)
Low noise: V
no
= 0.14 mVrms (Typ.)
(V
CC
= 37 V, R
L
= 8
Ω,
G
V
= 34dB, R
g
= 10 kΩ, BW = 20 Hz~20 kHz)
Very few external parts.
Built in audio muting circuit.
Built in thermal shut down protector circuit.
Built in output shifted to GND protection circuit. (AC short)
Available for using same PCB layout with: TA8200AH, TA8211AH, TA8216H
Operation supply voltage range (Ta = 25°C)
: V
CC (opr)
= 15~42 V
Weight: 4.04 g (typ.)
The TA8258HQ is plated with lead-free lead finishes, but the silicon pellet is attached to a heatsink with
lead-containing solder paste.
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TA8258HQ
Block Diagram
V
CC
6
Ripple Filter
IN1
AMP1
5
3
1
9
V
CC
IN1
4
OUT1
7
R
R
L
400
Ω
Pre-GND
400
Ω
20 kΩ
PW-GND 10
20 kΩ
AMP2
12
C
C
R
OUT2
R
L
IN2
2 IN2
Mute. TC
8
Mute
11
Application Information
1. Voltage gain
The closed loop voltage gain is determined by R
1
, R
2
.
Input
Output
7/12
R
+
R2
(dB)
G V
=
20
λ
og 1
R2
4/2
5/1
R
2
400
Ω
R
1
20 kΩ
20 k
Ω +
400
Ω
400
Ω
=
34 (dB)
=
20λog
R
1
+
R
2
+
R
3
(dB)
R
2
+
R
3
Input
Figure 1
G
V
=
20
λ
og
When R
3
=
220
Ω
G
V
∼
30 (dB)
−
is given.
4/2
R
3
5/1
R
2
400
Ω
R
1
20 kΩ
Output
7/12
Figure 2
Toshiba has confirmed that the G
V
(min) is approximately 28 (dB) on a regular printed circuit board. However,
if the value of R
2
+
R
3
is larger, the feedback voltage increases and oscillation will start. Determine the value of
R
2
+
R
3
to ensure proper startup behavior under actual usage conditions.
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2006-10-23
TA8258HQ
2. Muting
This product has an excellent muting system.
(1) Audio muting
This IC is possible to make audio muting operation by using 11 pin muting terminal.
Figure 3 shows the equivalent circuit in the muting circuit.
By reducing the voltage of 11 pin to 2.8 V or less, Q
1
will be ON.
Also the base voltage of Q
2
in the differential circuit that has Q
2
and Q
3
will be down.
When Q
2
is OFF, I
2
and I
5
dummy circuits will be operated, and it will shut down the input.
However, the bias circuit is operating after muting, and it takes power supply current at no signal.
8 pin is the capacitor terminal for reducing the pop noise, and it can make the time constant longer by
inserting the capacitor externally. If 11 pin is not used, connect 11 pin and 8 pin, then set the voltage
abode 4 V.
(2) IC internal muting at V
CC
OFF
When V
CC
=
8 V or less at V
CC
off, the detection circuit at V
CC
off is operated. And the base voltage of
Q
1
is reduced and the muting is operated in IC.
Dummy amp.
Main amp.
9
V
CC
Reference
voltage
The detection
circuit at
V
CC
→
OFF
Q
1
100
Ω
I
1
I
2
I
3
I
4
I
5
I
6
I
7
Q
5
30 kΩ
30 kΩ
Q
2
Q
3
Q
6
The
reference
voltage is
equal.
Q
4
Q
7
Q
8
Q
9
20 kΩ
OUT
400
Ω
7/12
Q
10
Q
11
11
Mute
8
Mute. TC
2/4
IN
1/5
NF
Figure 3
3. The Mounting Place of an Integrated Circuit
This IC cannot withstand the strong electromagnetic fields generated by a CRT. These are likely to cause
the device to exhibit malfunctions such as leakage.
Please ensure that the IC is kept away from CRT.
4. Preventive Measures Against Oscillation
To prevent oscillation, it is advisable to use capacitors made of polyester film, which have low
temperature and frequency fluctuation characteristics, as C.
The resistance R in series with C performs phase correction at high frequencies and improves the
oscillation allowance.
(1) Capacitor rating and type
(2) PCB layout
Note 1: Since the oscillation allowance varies according to the PCB layout, it is recommended that a standard
Toshiba PCB be used as a reference for design.
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2006-10-23
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