TDA7298 [STMICROELECTRONICS]
28W Hi-Fi AUDIO POWER AMPLIFIER WITH MUTE / STAND-BY; 28W高保真音频功率放大器静音/ STAND -BY
| 型号： | TDA7298 |
| 厂家： | 
ST |
| 描述： | 28W Hi-Fi AUDIO POWER AMPLIFIER WITH MUTE / STAND-BY |
| 文件： | 总11页 (文件大小：151K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TDA7298
28W Hi-Fi AUDIO POWER AMPLIFIER
WITH MUTE / STAND-BY
SUPPLY VOLTAGE RANGE UP TO ±22V
SPLIT SUPPLY OPERATION
HIGH OUTPUT POWER
(UP TO 28W MUSIC POWER)
LOW DISTORTION
MUTE/STAND-BY FUNCTION
NO SWITCH ON/OFF NOISE
AC SHORT CIRCUIT PROTECTION
THERMAL SHUTDOWN
Heptawatt
ORDERING NUMBER: TDA7298
ESD PROTECTION
DESCRIPTION
est power into both 4 and 8 loads even in
Ω
Ω
The TDA7298 is a monolithic integrated circuit in
Heptawatt package, intended for use as audio
class AB amplifier in TV or Hi-Fi field application.
Thanks to the wide voltage range and to the high
out current capability it’s able to supply the high-
presence of poor supply regulation.
The built in Muting/Stand-by function simplifies
the remote operations avoiding also switching on-
off noises.
TEST AND APPLICATION CIRCUIT
May 1997
1/11
TDA7298
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
±22
Unit
V
VS
IO
DC Supply Voltage
Output Peak Current (internally limited)
4
A
Ptot
Power Dissipation Tcase = 70 C
30
W
°
Top
Operating Temperature Range
0 to +70
-40 to +150
°C
°C
Tstg, Tj
Storage and Junction Temperature
PIN CONNECTION (Top view)
BLOCK DIAGRAM
2/11
TDA7298
THERMAL DATA
Symbol
Description
Thermal Resistance Junction-case
Value
Unit
Rth j-case
Max
2.5
C/W
°
ELECTRICAL CHARACTERISTICS (Refer to the test circuit, GV = 32dB; VS + 18V; f = 1KHz; Tamb
=
°
25 C, unless otherwise specified.)
Symbol
VS
Parameter
Supply Range
Test Condition
VS = +22V
Min.
+6
Typ.
Max.
+22
70
Unit
V
Iq
Total Quiescent Current
Input Bias Current
20
40
mA
Ib
+0.5
+15
+200
A
µ
VOS
IOS
Input Offset Voltage
Input Offset Current
mV
nA
W
PO
Music Output Power
IEC268-3 Rules (*)
VS = + 20, RL = 8Ω,
d = 10%, t = 1s
28
PO
Output Power (continuous RMS) d = 10%
RL = 4Ω VS = +14V
R = 8
20
20
24
24
W
W
Ω
L
d = 1%
RL = 4Ω VS = +14V
RL = 8Ω
17
17
W
W
d
Total Harmonic Distortion
R = 4 VS = +14V
Ω
L
P
O = 0.1 to 10W;
f = 100Hz to 15KHz
0.1
0.7
0.5
%
RL = 8Ω
P
O = 0.1 to 10W;
f = 100Hz to 15KHz
0.1
5
%
SR
GV
eN
Slew Rate
3
V/ s
µ
Open Loop Voltage Gain
Total Input Noise
80
dB
A Curve
f = 20Hz to 20KHz
2
3
µV
V
µ
10
Ri
SVR
TS
Input Resistance
500
40
KΩ
Supply Voltage Rejection
Thermal Shutdown
f = 100Hz, Vripple = 1VRMS
50
dB
145
C
°
MUTE/STAND-BY FUNCTION (Ref. –VS)
VTST-BY
VTPLAY
Iq ST-BY
ATTST-BY
Ipin3
Stand-by - Threshold
Play Threshold
1
1.8
2.7
1
V
4
3
V
Quiescent Current @ Stand-by
Stand-by Attenuation
Pin 3 Current @ Stand-by
Vpin 3 = 0.5V
mA
dB
70
90
–1
+10
A
µ
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 -10%
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 V2out/R1, where Vout 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.
3/11
TDA7298
APPLICATIONS SUGGESTIONS (See Test and Application Circuit)
The recommended values of the external components are those shown on the application circuit. Differ-
ent values can be used; the following table can help the designer.
Comp.
Value
Purpose
Larger Than
Smaller Than
R1
22K
Ω
(*)
Input Impedance
Increase of Input
Impedance
Decrease of Input
Impedance
R2
R3
R4
R5
R6
C1
560Ω
Closed Loop Gain set to
32dB (**)
Decrease of Gain
Increase of Gain
Increase of Gain
Decrease of Gain
22K (*)
Ω
22K
22K
4.7Ω
Ω
(*)
Input Impedance @ Mute
Stand-by Time Constant
Frequency Stability
Ω
Danger of oscillations
Danger of oscillations
1 F
µ
Input DC Decoupling
Higher Low-frequency
cut-off
C2
10µF
Feedback DC Decoupling
Higher Low-frequency
cut-off
C3
C4
10 F
Stand-by Time Constant
Frequency Stability
µ
0.100 F
Danger of Oscillations
µ
C5, C6
1000µF
Supply Voltage Bypass
(*) R1 = R3 = R4 for POP optimization
(**) Closed Loop Gain has to be ≥ 30dB
TYPICAL CHARACTERISTICS
Figure 2: Distortion vs. Output Power
Figure 1: Output Power vs. Supply Voltage
4/11
TDA7298
Figure 3: Output Power vs. Supply Voltage.
Figure 4: Distortion vs. Output Power.
Figure 5: Distortion vs. Frequency.
Figure 6: Distortion vs. Frequency.
Figure8: SupplyVoltage Rejection vs. Frequency.
Figure 7: QuiescentCurrent vs. Supply Voltage
5/11
TDA7298
Figure 9: Bandwidth.
Figure 10: Output Attenuation & Quiescent Cur-
rent vs. Vpin3
.
Figure 11: Total Power Dissipation & Efficiency
Figure 12: Total Power Dissipation & Efficiency
vs. Output Power.
vs. Output Power.
6/11
TDA7298
Figure 13: P.C. Board and Components Layout of the Circuit of Fig. 14 (1:1 scale)
Figure 14: Demo Board Schematic.
7/11
TDA7298
ators are off. Only the input MUTE stage is on in
order to prevent pop-on problems.
At Vpin3=1.8V the final stage current generators
are switched on and the amplifier operates in
MUTE.
MUTE/STAND-BY FUNCTION
The pin 3 (MUTE/STAND-BY) controls the ampli-
fier status by three different thresholds, referred
to -VS.
When its voltage is lower than the first threshold
(1V, with a +70mV hysteresis), the amplifier is in
STAND-BY and all the final stage current gener-
For Vpin3 =2.7V the amplifier is definitely on
(PLAY condition)
Figure 15.
8/11
TDA7298
SHORT-CIRCUIT PROTECTION
THERMAL PROTECTION
µ
The TDA7298 has an original circuit which pro-
tects the device during accidental short-circuit be-
tween output and GND / -Vs / +Vs, taking it in
STAND-BY mode, so limiting also dangerous DC
current flowing throught the loudspeaker.
If a short-circuit or an overload dangerous for the
final transistors are detected, the concerned SOA
circuit sends out a signal to the latching circuit
(with a 10µs delay time that prevents fast random
spikes from inadvertently shutting the amplifier
off) which makes Q1 and Q2 saturate (see Block
Diagram). Q1 immediately short-circuits to ground
the A point turning the final stage off while Q2
short-circuits to ground the external capacitor
driving the pin 3 (Mute/Stand-by) towards zero
potential.
The thermal protection operates on the 125 A
current generator, linearly decreasing its value
from 90°C on. By doing this, the A voltage slowly
decreases thus switching the amplifier first to
°
MUTE (at 145 C) and then to STAND-BY
(155°C).
Figure 16: Thermal Protection Block Diagram
Only when the pin 3 voltage becomes lower than
1V, the latching circuit is allowed to reset itself
and restart the amplifier, provided that the short-
circuit condition has been removed. In fact, a win-
dow comparator is present at the output and it is
aimed at preventing the amplifier from restarting if
the output voltage is lower than 0.35 Total Supply
Voltage or higher than 0.65 Total Supply Voltage.
If the output voltage lies between these two
thresholds, one may reasonably suppose the
short-circuit has been removed and the amplifier
may start operating again.
The PLAY/MUTE/STAND-BY function pin (pin 3)
is both ground- and positive supply-compatible
and can be interfaced by means of the R5, C3 net
either to a TTL or CMOS output (µ-Processor) or
to a specific application circuit.
The maximum allowable power dissipation de-
pends on the size of the external heatsink (ther-
mal resistance case-ambient); figure 17 shows
the dissipable power as a function of ambient
temperaturefor different thermal resistance.
The R5, C3 net is fundamental, because connect-
ing this pin directly to a low output impedance
driver such as TTL gate would prevent the correct
operation during a short-circuit. Actually a final
stage overload turns on the protection latching
circuit that makes Q2 try to drive the pin 3 voltage
under 0.8 V. Since the maximum current this pin
can stand is 3 mA, one must make sure the fol-
lowing condition is met:
Figure 17: Maximum Allowable Power Dissipa-
tion vs. Ambient Temperature.
(VA − 0.7V)
R5 ≥
3mA
Ω
that yields: R5, min = 1.5 K with VA=5V.
In order to prevent pop-on and -off transients, it is
advisable to calculate the C3, R5 net in such a
way that the STAND-BY/MUTE and MUTE/PLAY
threshold crossing slope (positive at the turn-on
and vice-versa) is less than 100 V/sec.
9/11
TDA7298
HEPTAWATT PACKAGE MECHANICAL DATA
mm
inch
TYP.
DIM.
MIN.
TYP.
MAX.
4.8
MIN.
MAX.
0.189
0.054
0.110
0.053
0.022
0.031
0.035
0.105
0.205
0.307
0.409
0.409
A
C
1.37
2.8
D
2.4
1.2
0.094
0.047
0.014
0.024
D1
E
1.35
0.55
0.8
0.35
0.6
F
F1
G
0.9
2.41
4.91
7.49
2.54
5.08
7.62
2.67
5.21
7.8
0.095
0.193
0.295
0.100
0.200
0.300
G1
G2
H2
H3
L
10.4
10.4
10.05
0.396
16.97
14.92
21.54
22.62
0.668
0.587
0.848
0.891
L1
L2
L3
L5
L6
L7
M
2.6
15.1
6
3
0.102
0.594
0.236
0.118
0.622
0.260
15.8
6.6
2.8
0.110
0.200
M1
Dia
5.08
3.65
3.85
0.144
0.152
10/11
TDA7298
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications men-
tioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.
SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without ex-
press written approval of SGS-THOMSON Microelectronics.
1997 SGS-THOMSON Microelectronics - All Rights Reserved
HEPTAWATT is a Trademark of companies belonging to the SGS-THOMSON Microelectronics Group
SGS-THOMSON Microelectronics GROUP OF COMPANIES
Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands -
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11/11
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