TDA7245
5W AUDIO AMPLIFIER WITH MUTING AND STAND-BY
MUTING AND STAND-BY FUNCTIONS
VOLTAGE RANGE UP TO 30V
HIGH SUPPLY VOLTAGE REJECTION
SVR TYP = 50dB (f = 100Hz)
MUSIC POWER = 12W (R
L
= 4
, d = 10%)
PROTECTION AGAINST CHIP OVER
TEMPERATURE
DESCRIPTION
The TDA7245 is a monolithic integrated circuit in
9+9 POWERDIP package, intended for use as
low frequency power amplifier in a wide range of
applications in radio and TV sets.
March 1995
Figure 1: Test and Application Circuit
Powerdip 9+9
ORDERING NUMBER: TDA7245
1/11
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
V
S
Supply Voltage
30
V
I
O
Output Peak Current (non repetitive t = 100
s)
3
A
I
O
Output Peak Current (repetitive, f > 20Hz)
2.5
A
P
tot
Power Dissipation at T
amb
= 80
C
at
T
case
= 70
C
1
6
W
W
T
stg
, T
j
Storage and junction Temperature
-40 to 150
C
PIN CONNECTION (Top view)
THERMAL DATA
Symbol
Description
Value
Unit
R
th j-case
Rth j-amb
Thermal Resistance junction-case
Thermal Resistance junction-ambient
Max
Max
15
70
C/W
C/W
TDA7245
2/11
ELECTRICAL CHARACTERISTICS (Refer to the test circuit, T
amb
= 25
C, f = 1kHz; unless otherwise
specified).
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
V
S
Supply Voltage
12
30
V
V
O
Quiescent Output Voltage
V
S
= 24V
11.6
V
I
d
Quiescent Drain Current
V
S
= 14V
V
S
= 28V
17
21
35
mA
mA
P
O
Output Power
d = 1%, f = 1KHz
V
S
= 14V, R
L
= 4
V
S
= 18V, R
L
= 8
d = 10%, f = 1KHz
V
S
= 14V, R
L
= 4
V
S
= 18V, R
L
= 8
Music Power (*)
V
S
= 24V, d = 10%, R
L
= 4
4
4
4
5
5
12
W
W
W
W
W
d
Harmonic Distortion
V
S
= 14V, R
L
= 4
,
P
O
= 50mW to 3W
f = 1KHz
f = 10KHz
V
S
= 18V, R
L
= 8
,
P
O
= 50mW to 3.5W
f = 1KHz
f = 10KHz
V
S
= 22V, R
L
= 16
,
P
O
= 50mW to 3W
f = 1KHz
f = 10KHz
0.15
0.8
0.12
0.5
0.08
0.4
0.5
%
%
%
%
%
%
R
I
Input Impedance
f = 1kHz
30
k
BW
Small signal bandwidth (-3dB)
P
O
= 1W; R
L
= 4
V
S
= 14V
50 to 40,000
Hz
G
V
Voltage Gain (open loop)
f = 1kHz
75
dB
G
V
Voltage Gain (closed loop)
f = 1kHz
39
40
41
dB
e
N
Total Input Noise
B = 22 - 22,000Hz
R
s
= 50
R
s
= 1k
R
s
= 10k
1.7
2
3
6
mV
V
V
S/N
Signal to Noise Ratio
V
S
= 18V; R
L
= 8
P
O
= 5W; R
S
= 10K
86
dB
SVR
Supply Voltage Rejection
V
S
= 16.5V; R
L
= 8
; f = 100Hz
R
s
= 10k
;
V
r
= 0.5Vrms
40
50
dB
T
sd
Thermal shut-down Junction
Temperature
150
C
MUTE FUNCTION
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
V
m
Pin 4 DC Voltage
Mute SW Open (play)
6.4
V
ATT
m
Muting Attenuation
f = 100Hz to 10kHz
60
65
dB
TDA7245
3/11
ELECTRICAL CHARACTERISTCS (Continued)
STAND-BY FUNCTION
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
V
st-by
Pin 5 DC Voltage
Mute SW Open (play)
6.4
V
I
st- by
Pin 5 Current
Mute SW Closed (st-by)
160
280
A
ATT
st-by
Stand-by Attenuation
f = 100Hz to 10kHz
70
90
dB
V
t
Stand-by Threshold (pin 5)
3.8
V
I
d st-by
Stand-by Current
V
S
= 14V
1
3
mA
Note (*):
MUSIC POWER CONCEPT
MUSIC POWER is ( according to the IEC clauses n.268-3 of Jan 83) the maximal power which the amplifier is capable of producing across the
rated load resistance (regardless of non linearity) 1 sec after the application of a sinusoidal input signal of frequency 1KHz.
According to this definition our method of measurement comprises the following steps:
1) Set the voltage supply at the maximum operating value -20%
2) Apply a input signal in the form of a 1KHz tone burst of 1 sec duration; the repetition period of the signal pulses is > 60 sec
3) The output voltage is measured 1 sec from the start of the pulse
4) Increase the input voltage until the output signal show a THD = 10%
5) The music power is then V
2
out
/R1
,
where V
out
is the output voltage measured in the condition of point 4) and R1 is the rated load impedance
The target of this method is to avoid excessive dissipation in the amplifier.
Figure 2: Schematic Diagram
TDA7245
4/11
APPLICATION SUGGESTIONS
The recommended values of the external components are those shown on the application circuit of fig.1.
Different values can be used. The following table can help the dsigner.
Component
Rec. Value
Purpose
Larger than Rec. Value
Smaller than Rec. Value
R1
20K
St-By Biasing
Incorrect St-By Function
Worse POP and Shorter
Delay at St-By Insertion
R2(*)
27K
Feedback
Resistors
Increase of Gain
Decrease of Gain
R3(*)
270
Decrease of Gain
Increase of Gain
R4
1
Frequency Stability
Danger of Oscillations
C1
22
F
St-By Capacitor
Longer ON/OFF Delay
Time at St-By IN/OUT
Worse POP and Shorter
Delay at St-By insertion
C2
47
F
SVR Capacitor
Worse Turn-On POP by
V
S
and St-By
Degradation of SVR
C3
0.1
F
Input Capacitance
Higher Low Frequency
Cut-off
C4
2.2
F
Inverting Input DC
Decoupling
Higher Low Frequency
Cut-off
C5
470
F
Supply Voltage
Danger of Oscillations
C6
0.22
F
Frequency Stability
Danger of Oscillations
C7
1000
F
Output DC Decoupling
Higher Low Frequency
Cut-off
(*) The value of closed loop gain (G
V
= 1 + R2/R3) must be higher than 25dB.
Figure 3: P.C. Board and Components Layout of the Circuit of fig 2 (1:1 scale)
TDA7245
5/11
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