TA8270HQ
TOSHIBA Bipolar Linear Integrated Circuit Silicon Monolithic
TA8270HQ
Max Power 43 W BTL
×
4 ch High Efficiency Audio Power IC
The TA8270HQ is TOSHIBA original class KB (Keyed BTL)
high efficiency audio amplifier for car audio applications.
The Class KB solutions is no need an external LPF for EMI
rejection and then it is possible to design for limited small DIN
size chassis.
Conversely, the class D must need an external LPF.
Power dissipation of class KB is no more than a half of the
class AB solutions.
Therefore, it is possible to design a smaller heatsink and keep
lower internal temperature into the car audio set; internal
Weight: 7.7 g (typ.)
cassette part, CD/MD part etc.
This IC can generate more high power and high quality sounds
as it is included the pure complementary PNP and NPN transistor output stage.
Additionally, stand-by function, mute function, various kind of protector and diagnosis function included output
offset voltage detection for car audio use are built-in.
Features
•
High power : P
OUT
MAX (1) = 43 W (typ.)
(V
CC
= 14.4 V, f = 1 kHz, JEITA max, R
L
= 4
Ω)
: P
OUT
MAX (2) = 40 W (typ.)
(V
CC
= 13.7 V, f = 1 kHz, JEITA max, R
L
= 4
Ω)
: P
OUT
(1) = 28 W (typ.)
(V
CC
= 14.4 V, f = 1 kHz, THD = 10%, R
L
= 4
Ω)
: P
OUT
(2)
=
24 W (typ.)
(V
CC
= 13.2 V, f = 1 kHz, THD = 10%, R
L
= 4
Ω)
•
•
•
•
•
•
•
Built-in diagnosis circuit (pin 25)
Low distortion ratio: THD = 0.04% (typ.)
(V
CC
= 13.2 V, f = 1 kHz, P
OUT
= 2 W, R
L
= 4
Ω)
Low noise: V
NO
=
0.13 mV
rms
(typ.)
(V
CC
= 13.2 V, R
g
= 0
Ω,
G
V
= 26dB, BW = 20 Hz~20 kHz)
Built-in stand-by switch (pin 4)
Built-in muting function (pin 22)
Built-in various protection circuit
: Thermal shut down, over voltage, out to GND, out to V
CC
, out to out short
Operating supply voltage: V
CC (opr)
= 9~16 V
Note 1: Install the product correctly. Otherwise, it may result in break down, damage and/or degradation to the
product or equipment.
Note 2: These protection functions are intended to avoid some output short circuits or other abnormal conditions
temporarily. These protect functions do not warrant to prevent the IC from being damaged.
- In case of the product would be operated with exceeded guaranteed operating ranges, these
protection features may not operate and some output short circuits may result in the IC being
damaged.
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TA8270HQ
Block Diagram
C
5
1
TAB
20
V
CC1
6
V
CC2
OUT1 (+)
9
C
1
11
IN1
PW-GND1 8
OUT1 (−)
C
7
R
2
R
2
C
7
C
3
R
L
RF
7
OUT2 (+)
C
1
12
IN2
PW-GND2 2
OUT2 (−)
C
7
R
2
R
2
C
7
5
R
L
RR
3
CENTER
16
C
6
OUT3 (+)
C
1
15
IN3
PW-GND3 18
OUT3 (−)
C
7
R
2
R
2
C
7
17
R
L
LF
19
OUT4 (+)
C
1
14
IN4
PW-GND4 24
OUT4 (−)
C
7
R
2
R
2
C
7
21
R
L
LR
23
PRE-GND
13
RIP
10
C
2
STBY
4
DIAGNOSIS
MUTE
OUT
25
22
R
1
C
4
: PRE-GND
: PW-GND
Note3: Some of the functional blocks, circuits, or constants in the block diagram may be omitted or simplified for
explanatory purpose.
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TA8270HQ
Caution and Application Method
(Description is made only on the single channel.)
1. Voltage Gain Adjustment
This IC has no NF (negative feedback) terminals. Therefore, the voltage gain can’t adjusted, but it makes
the device a space and total costs saver.
Amp. 2A
Amp. 1
Input
Amp. 2B
Figure 1 Block Diagram
The voltage gain of Amp.1:
G
V1
=
0dB
The voltage gain of Amp.2A, B:
G
V2
=
20dB
The voltage gain of BLT Connection: G
V (BTL)
=
6dB
Therefore, the total voltage gain is decided by expression below.
G
V
=
G
V1
+
G
V2
+
G
V (BTL)
=
0
+
20
+
6
=
26dB
2. Stand-by SW Function
(pin 4)
By means of controlling pin 4 (stand-by terminal)
to high and low, the power supply can be set to ON
and OFF. The threshold voltage of pin 4 is set at
about 3V
BE
(typ.), and the power supply current is
about 2
µA
(typ.) at the stand-by state.
V
CC
ON Power
OFF
4
10 kΩ
≈
2V
BE
to BIAS
CUTTING CIRCUIT
Control Voltage of pin 4: V
SB
Stand-by
ON
OFF
Power
OFF
ON
V
SB
(V)
0~1.5
3~V
CC
Figure 2 With pin 4 set to High,
Power is turned ON
Adjustage of Stand-by SW
(1)
(2)
Since V
CC
can directly be controlled to ON or OFF by the microcomputer, the switching relay can be
omitted.
Since the control current is microscopic, the switching relay of small current capacity is satisfactory
for switching
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TA8270HQ
Large current capacity switch
BATTERY
RELAY
BATTERY
V
CC
V
CC
– Conventional Method –
FROM
MICROCOMPUTER
Small current capacity switch
BATTERY
DIRECTLY FROM
MICROCOMPUTER
BATTERY
Stand-By V
CC
Stand-By V
CC
– Stand-by Switch Method –
Figure 3
3. Muting Function
(pin 22)
By means of controlling pin 22 less than 0.5 V, it can make the audio muting condition.
The muting time constant is decided by R
1
and C
4
and these parts is related the pop noise at power
ON/OFF.
The series resistance; R1 must be set up less than 10 kΩ to get enough muting attenuation.
The muting function have to be controlled by a transistor, FET and
µ-COM
port which has I
MUTE
>
250
µA
ability.
Pin 22 terminal voltage has the temperature characteristics of 4.6 V (low temperature) to 3.2 V (high
temperature).
Therefore, it is need to design with attention as using the microcontroller of which operating voltage is
less than 5 V.
Terminal 22 may not be pulled up and shall be controlled by OPEN/LOW.
When it is obliged to do, it must be pulled up via diode, because it has to defend flowing reverse current
to internal circuit of pin 22.
<Recommended Application>
ATT – V
MUTE
20
I (100
µA)
I
MUTE (OFF)
22
C
4
R
1
A
(dB)
10 kΩ
0
−20
−40
−60
5 kΩ
I
MUTE
V
MUTE
<Application for pulled up>
Mute attenuation
ATT
VCC
=
13.2 V
−80
−100
0
0.4
0.8 1 1.2
1.6
Po
=
10 W
PL
=
4
Ω
f
=
1 kHz
BW
=
400~30 kHz
2
2.4
2.8 3
I (100
µA)
I
MUTE (OFF)
22
C
4
R
1
I
MUTE
V
MUTE
Point A voltage: VMUTE
(V)
Figure 4 Muting Function
Figure 5 Mute Attenuation
−
V
MUTE
(V)
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TA8270HQ
4. Center Amp Pin: Center (pin 16)
Output from the center amp, which determines the
reference voltage for output in the IC, is connected to
this pin.
Connecting a capacitor to the pin rejects the ripple
component, reducing the distortion ratio of the audio
output.
CENTER
16
Center amp
PW-GND
Figure 6 CENTER
5.
Diagnosis Output
(pin 25)
This diagnosis output terminal of pin 25 has open collector output structure on chip as shown in Figure 7.
In case diagnosis circuit that detect unusual case is operated, NPN transistor. (Q1) or (Q2) is turned on.
It is possible to protect all the system of apparatus as well as power IC protection.
In case of being unused this function, use this IC as open-connection on pin 25.
5V
V
5V
pin 25 voltage
GND
t
Offset
Det.
Clip Det.
Short Det.
Output clip
detector
Output short
protector
Over voltage
protector
Q1
Base voltage of Q1
Base voltage of Q2
5.8 kΩ
Output offset
voltage detector
25
Q2
pin 25: Open collector output (active low)
Figure 7 Self Diagnosis Output
5.1
In Case of Shorting Output to V
CC
/GND or Over Voltage Power Supplied
NPN transistor. (Q1) is turned on.
Threshold of over voltage protection: V
CC
=
22 V (typ.)
5V
µ-COM
LED/LCD
ALARM
(Flashing)
(Announcement from a speaker.)
(Relay
→
OFF)
25
REGULATOR
→
OFF
MEMORY (Count and record)
Figure 8
5.2
Application 1
In Case of Shorting Output to Output
NPN transistor. (Q1) is turned on and off in response to the input signal voltage.
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