TA8207K
TOSHIBA Bipolar Linear Integrated Circuit Silicon Monolithic
TA8207K
Low Frequency Power Amplifier
TA8207K is an audio power IC with built−in two channels
developed for portable radio cassette tape recorder with power on
/ off switch.
Because of the parts reduction and SIP (single inline package),
space merit is remarkable.
Thermal shut down protection circuit is built in.
Features
·
High power: P
OUT
= 2.5W (typ.)
(V
CC
= 9V, R
L
= 4Ω, f =
1kHz,
THD =
10%)
P
OUT
= 4.6W (typ.)
(V
CC
=
12V,
R
L
= 4Ω, f =
1kHz,
THD =
10%)
·
·
·
·
·
·
Low popping noise at power on
Small quiescent current: I
CCQ
= 21mA (typ.) (V
CC
= 9V, V
IN
= 0)
Soft clip
Built−in thermal shut down protection circuit
Best for supply voltage 9V,
12V
Operation supply voltage range: V
CC
= 6~15V
Weight: 3.2g (typ.)
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2002-10-30
TA8207K
Block Diagram / Test Circuit
(*1): This IC can be used without coupling capacitor (C
IN
). If volume slide noise occured by input offset voltage is
undesirable, it needs to use the capacitor (C
IN
).
(*2): The condenser between the (3) pin and the GND (C
11
) is for reducing pop noise when the power on / off switch
(SW
1
) is set to on / off.
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2002-10-30
TA8207K
Application Information And Application Method
1.
Adjustment of voltage gain
The voltage gain G
V
is obtained as follows by R
1
,
R
2
and R
f
in Fig.
1.
G V
=
20
l
og
R f
+
R1
+
R2
R f
+
R1
When R
f
= 0Ω
When R
f
=
120Ω
G
V
= 56.5dB (typ.)
G
V
= 45dB (typ.)
By increasing R
f
, reduction of G
V
is possible. However, since the feedback increase is liable to produce
oscillation, it is recommended to use this at 40dB or over.
2. Thermal shut-down circuit
The thermal shut-down circuit is built in for the purpose of preventing the destruction of IC due to the
abnormal temperature rise when the heat radiation is insufficient.
The operation temperature is set at radiation fin temperature
175°C
(typ.).
At this temperature or over the bias is interrupted to prevent the destruction of IC.
3. Input stage
The input circuit of this IC is as shown
in Fig.2.
PNP Tr: Q1 is provided in the input
circuit so as to make its usage possible
without the input coupling capacitor.
However, at pin(6) and (7), max 60mV
offset voltage is produced.
Application after checking volume slide
noise is recommended.
For cutting the volume slide noise,
insert the input capacitor: C
IN
in series
to interrupt the DC component.
4. Oscillation preventive measures
For oscillation preventive capacitor C
6
and C
7
between the output terminal and GND, it is recommended to
use polyester film capacitor having good characteristics for temperature and for high frequency.
Since the characteristics of the capacitor is liable to be influenced by the temperature, use this capacitor
after the temperature test to check the oscillation allowance.
In addition, as the position of the electrolytic capacitor has remarkable influence on the oscillation, connect
C
10
to V
CC
at the nearest possible position from power GND.
At using this application with the voltage gain reduced, oscillation is liable to be produced.
Apply the capacitor after checking enough for its capacity, type and mounting position.
(*): As the oscillation allowance varies according to the printed pattern layout, the standard printed board of TOSHIBA
is recommended to be referrend to design it.
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2002-10-30
TA8207K
5. Power on / off switch
There is power on / off switch at (3) pin. However, output power is changed by (3) pin supply voltage when (3)
pin supply voltage is not same (12) pin supply voltage, after referring to attached date, select (3) pin supply
voltage.
6. Input voltage
When the excessive signal is input, turning-up is produced in the clip waveform. The turning-up point is
V
IN
= 300mV
rms
(typ.): V
CC
= 9V, R
L
= 4Ω, f =
1kHz:
Enough care must be taken for this phenomenon.
7. GND line
GND pin is not separated for pre-GND and for PW-GND. That is liable to cause distortion and cross talk
worse. Before use this IC, please check it.
Standard Print Pattern
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2002-10-30
DSP and ARM Processors
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