STMICROELECTRONICS TDA7385

TDA7385

4 x 30W QUAD BRIDGE CAR RADIO AMPLIFIER
HIGH OUTPUT POWER CAPABILITY:
4 x 35W/4Ω MAX.
4 x 30W/4Ω EIAJ
4 x 22W/4Ω @ 14.4V, 1KHz, 10%
4 x 18.5W/4Ω @ 13.2V, 1KHz, 10%
CLIPPING DETECTOR
LOW DISTORTION
LOW OUTPUT NOISE
ST-BY FUNCTION
MUTE FUNCTION
AUTOMUTE AT MIN. SUPPLY VOLTAGE DETECTION
DIAGNOSTICS FACILITY FOR:
– CLIPPING
– OUT TO GND SHORT
– OUT TO V S SHORT
– THERMAL SHUTDOWN
LOW EXTERNAL COMPONENT COUNT:
– INTERNALLY FIXED GAIN (26dB)
– NO EXTERNAL COMPENSATION
– NO BOOTSTRAP CAPACITORS
PROTECTIONS:
OUTPUT SHORT CIRCUIT TO GND, TO VS,
FLEXIWATT25
ORDERING NUMBER: TDA7385
ACROSS THE LOAD
VERY INDUCTIVE LOADS
OVERRATING CHIP TEMPERATURE WITH
SOFT THERMAL LIMITER
LOAD DUMP VOLTAGE
FORTUITOUS OPEN GND
REVERSED BATTERY
ESD PROTECTION
DESCRIPTION
The TDA7385 is a new technology class AB
Audio Power Amplifier in Flexiwatt 25 package
BLOCK AND APPLICATION DIAGRAM
Vcc1
Vcc2
2.200µF
100nF
ST-BY
DIAGN. OUT
MUTE
OUT1+
IN1
OUT10.1µF
PW-GND
OUT2+
IN2
OUT20.1µF
PW-GND
OUT3+
IN3
OUT30.1µF
PW-GND
OUT4+
IN4
OUT40.1µF
PW-GND
AC-GND
0.1µF
SVR
47µF
TAB
S-GND
D93AU002C
October 1999
1/12
TDA7385
DESCRIPTION (continued)
Thanks to the fully complementary PNP/NPN output configuration the TDA7385 allows a rail to rail
output voltage swing with no need of bootstrap
capacitors. The extremely reduced components
count allows very compact sets.
The on-board clipping detector simplifies gain
compression operations. The fault diagnostics
makes it possible to detect mistakes during CarRadio assembly and wiring in the car.
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
Operating Supply Voltage
18
V
VCC (DC)
DC Supply Voltage
28
V
VCC (pk)
Peak Supply Voltage (t = 50ms)
50
V
Output Peak Current:
Repetitive (Duty Cycle 10% at f = 10Hz)
Non Repetitive (t = 100µs)
4.5
5.5
A
A
Power dissipation, (Tcase = 70°C)
80
W
VCC
IO
Ptot
Tj
Junction Temperature
150
°C
Tstg
Storage Temperature
– 55 to 150
°C
designed for high end car radio applications.
PIN CONNECTION (Top view)
D94AU117B
P-GND4
DIAGNOSTICS
MUTE
OUT4-
VCC
OUT4+
OUT3-
OUT3+
P-GND3
IN3
AC-GND
IN4
IN2
S-GND
IN1
SVR
OUT1+
P-GND1
VCC
OUT1-
ST-BY
OUT2+
OUT2-
TAB
25
P-GND
1
THERMAL DATA
2/12
Symbol
Parameter
Rth j-case
Thermal Resistance Junction to Case
Max.
Value
Unit
1
°C/W
TDA7385
ELECTRICAL CHARACTERISTICS (VS = 14.4V; f = 1KHz; Rg = 600Ω; RL = 4Ω; Tamb = 25°C;
Refer to the Test and application circuit (fig.1), unless otherwise specified.)
Symbol
Parameter
Iq1
Quiescent Current
VOS
Output Offset Voltage
Gv
Voltage Gain
Po
Output Power
Po EIAJ
EIAJ Output Power (*)
Test Condition
mV
27
dB
THD = 10%; VS = 14V
THD = 5%; VS = 14V
THD = 1%; VS = 14V
19
17
16
21
19
17
W
W
W
THD = 10%; VS = 13.2V
THD = 1%; VS = 13.2V
17
14
18.5
15
W
W
VS = 13.7V
27.5
30
W
33
eNo
Output Noise
”A” Weighted
Bw = 20Hz to 20KHz
SVR
Supply Voltage Rejection
f = 100Hz
35
0.04
50
65
50
W
0.3
%
150
µV
µV
65
dB
20
Hz
75
Ri
Input Impedance
CT
Cross Talk
f = 1KHz
ISB
St-By Current Consumption
St-By = LOW
VSB out
St-By OUT Threshold Voltage
(Amp: ON)
VSB IN
St-By IN Threshold Voltage
(Amp: OFF)
Mute Attenuation
VO = 1Vrms
80
VM out
Mute OUT Threshold Voltage
(Amp: Play)
3.5
VM in
Mute IN Threshold Voltage
(Amp: Mute)
Im (L)
Muting Pin Current
VMUTE = 1.5V
(Source Current)
ICDOFF
Clipping Detector ”OFF” Output
Average Current
THD = 1% (**)
ICDON
Clipping Detector ”ON” Output
Average Current
THD = 10% (**)
AM
mA
100
W
W
VS = 14.4V
High Cut-Off Frequency
Unit
26
Po = 4W
fch
300
22
18
Max. Output Power (*)
Low Cut-Off Frequency
Max.
180
25
Distortion
fcl
Typ.
20
16.5
THD = 10%
THD = 1%
THD
Po max.
Min.
KHz
70
100
50
70
KΩ
dB
100
3.5
1.5
5
90
V
dB
V
10
1.5
V
16
µA
µA
100
100
µA
V
240
350
µA
(*) Saturated square wave output.
(**) Diagnostics output pulled-up to 5V with 10KΩ series resistor.
3/12
TDA7385
Figure 1: Standard Test and Application Circuit
C8
0.1µF
C7
2200µF
Vcc1-2
Vcc3-4
6
R1
ST-BY
20
9
4
10K
R2
C9
1µF
MUTE
8
22
47K
C10
1µF
5
C1
2
11
IN1
17
12
18
C2 0.1µF
IN3
C3 0.1µF
21
IN4
24
14
S-GND
C5
0.1µF
OUT4
23
13
16
10
25
SVR
C6
47µF
1
TAB
D94AU179B
DIAGNOSTICS
4/12
OUT3
19
15
C4 0.1µF
OUT2
3
0.1µF
IN2
OUT1
7
TDA7385
Figure 2: P.C.B. and component layout of the figure 1 (1:1 scale)
COMPONENTS &
TOP COPPER LAYER
TDA7385
BOTTOM COPPER LAYER
5/12
TDA7385
Figure 3: Quiescent Current vs. Supply Voltage
Figure 4: Quiescent Output Voltage vs. Supply
Voltage
Figure 5: Output Power vs. Supply Voltage
Figure 6: Distortion vs. Output Power
Figure 7: Distortion vs. Frequency.
Figure 8: Supply
Voltage
Rejection
Frequency by varying C6
R g = 600Ω
Vripple = 1Vrms
6/12
vs.
TDA7385
Figure 9: Output Noise vs. Source Resistance
Figure 10: Power Dissipation & Efficiency vs.
Output Power
Ptot (W)
Ptot
R g (Ω)
APPLICATION HINTS (ref. to the circuit of fig. 1)
BIASING AND SVR
As shown by fig. 11, all the TDA7385’s main sections, such as INPUTS, OUTPUTS AND AC-GND
(pin 16) are internally biased at half Supply Voltage level (Vs/2), which is derived from the Supply
Voltage Rejection (SVR) block. In this way no current flows through the internal feedback network.
The AC-GND is common to all the 4 amplifiers
and represents the connection point of all the inverting inputs.
Both individual inputs and AC-GND are connected to Vs/2 (SVR) by means of 100KΩ resistors.
To ensure proper operation and high supply voltage rejection, it is of fundamental importance to
provide a good impedance matching between INPUTS and AC-GROUND terminations. This implies that C1, C2, C3, C4, C5 CAPACITORS HAVE
TO CARRY THE SAME NOMINAL VALUE AND
THEIR TOLERANCE SHOULD NEVER EXCEED
±10 %.
Besides its contribution to the ripple rejection, the
SVR capacitor governs the turn ON/OFF time sequence and, consequently, plays an essential role
in the pop optimization during ON/OFF transients.
To conveniently serve both needs, ITS MINIMUM
RECOMMENDED VALUE IS 10µF.
Figure 11: Input/OutputBiasing.
100KΩ
+
0.1µF
C1 ÷ C4
8KΩ
IN
400Ω
400Ω
VS
8KΩ
10KΩ
70KΩ
10KΩ
SVR
100KΩ
AC_GND
47µF
C6
0.1µF
C5
+
TOWARDS
OTHER CHANNELS
D95AU302
7/12
TDA7385
INPUT STAGE
The TDA7385’S inputs are ground-compatible
and can stand very high input signals (± 8Vpk)
without any performances degradation.
If the standard value for the input capacitors
(0.1µF) is adopted, the low frequency cut-off will
amount to 16 Hz.
STAND-BY AND MUTING
STAND-BY and MUTING facilities are both
CMOS-COMPATIBLE. If unused, a straight connection to Vs of their respective pins would be admissible. Conventional low-power transistors can
be employed to drive muting and stand-by pins in
absence of true CMOS ports or microprocessors.
R-C cells have always to be used in order to
smooth down the transitions for preventing any
audible transient noises.
Since a DC current of about 10 uA normally flows
out of pin 22, the maximum allowable muting-series resistance (R2) is 70KΩ, which is sufficiently
high to permit a muting capacitor reasonably
small (about 1µF).
If R2 is higher than recommended, the involved
risk will be that the voltage at pin 22 may rise to
above the 1.5 V threshold voltage and the device
will consequently fail to turn OFF when the mute
line is brought down.
About the stand-by, the time constant to be assigned in order to obtain a virtually pop-free transition has to be slower than 2.5V/ms.
tion with microprocessor-driven audioprocessors.
The maximum load that pin 25 can sustain is
1KΩ.
Due to its operating principles, the clipping detector has to be viewed mainly as a power-dependFigure 12: Diagnostics circuit.
R
25
VREF
Vpin 25
TDA7385
D95AU303
Figure 13: Clipping Detection Waveforms.
DIAGNOSTICS FACILITY
The TDA7385 is equipped with a diagnostics circuitry able to detect the following events:
CLIPPING in the output stage
OVERHEATING (THERMAL SHUT-DOWN
proximity)
OUTPUT MISCONNECTIONS (OUT-GND &
OUT-Vs shorts)
Diagnostics information is available across an
open collector output located at pin 25 (fig. 12)
through a current sinking whenever at least one
of the above events is recognized.
Among them, the CLIPPING DETECTOR acts in
a way to output a signal as soon as one or more
power transistors start being saturated.
As a result, the clipping-related signal at pin 25
takes the form of pulses, which are perfectly syncronized with each single clipping event in the
music program and reflect the same duration time
(fig. 13). Applications making use of this facility
usually operate a filtering/integration of the pulses
train through passive R-C networks and realize a
volume (or tone bass) stepping down in associa8/12
ent feature rather than frequency-dependent.This
means that clipping state will be immediately signaled out whenever a fixed power level is
reached, regardless of the audio frequency.
In other words, this feature offers the means to
counteract the extremely sound-damaging effects
of clipping, caused by a sudden increase of odd
order harmonics and appearance of serious intermodulation phenomena.
Another possible kind of distortion control could
be the setting of a maximum allowable THD limit
(e.g. 0.5 %) over the entire audio frequency
range. Besides offering no practical advantages,
this procedure cannot be much accurate, as the
non-clipping distortion is likely to vary over frequency.
In case of OVERHEATING, pin 25 will signal out
the junction temperature proximity to the thermal
shut-down threshold. This will typically start about
o
2 C before the thermal shut-down threshold is
TDA7385
Figure 14: Diagnostics Waveforms.
ST-BY PIN
VOLTAGE
t
MUTE PIN
VOLTAGE
t
Vs
OUTPUT
WAVEFORM
t
Vpin 25
WAVEFORM
t
CLIPPING
SHORT TO GND
OR TO Vs
D95AU304
reached.
As various kind of diagnostics information is available at pin 25 (CLIPPING, SHORTS AND OVERHEATING), it may be necessary to operate some
distinctions on order to treat each event separately. This could be achieved by taking into account the intrinsically different timing of the diagnostics output under each circumstance.
THERMAL
PROXIMITY
In fact, clipping will produce pulses normally
much shorter than those present under faulty conditions. An example of circuit able to distinguish
between the two occurrences is shown by fig. 15.
STABILITY AND LAYOUT CONSIDERATIONS
If properly layouted and hooked to standard carradio speakers, the TDA7385 will be intrinsically
stable with no need of external compensations
Figure 15.
VREF
T1
25
+
T2
VREF1
-
TDA7385
T1 << T2
VREF ≥ VREF1 >> VREF2
+
CLIP DET. (TO GAIN
COMPRESSOR/
TONE CONTROL)
FAULT, THERMAL SHUTDOWN
(TO POWER SUPPLY
SECTION, µP VOLTAGE
REGULATOR, FLASHING SYSTEM)
VREF2
D95AU305
9/12
TDA7385
such as output R-C cells. Due to the high number
of channels involved, this translates into a very
remarkable components saving if compared to
similar devices on the market.
To simplify pc-board layout designs, each amplifier stage has its own power ground externally accessible (pins 2,8,18,24) and one supply voltage
pin for each couple of them.
Even more important, this makes it possible to
achieve the highest possible degree of separation
among the channels, with remarkable benefits in
terms of cross-talk and distortion features.
About the layout grounding, it is particularly im-
10/12
portant to connect the AC-GND capacitor (C5) to
the signal GND, as close as possible to the audio
inputs ground: this will guarantee high rejection of
any common mode spurious signals.
The SVR capacitor (C6) has also to be connected
to the signal GND.
Supply filtering elements (C7, C8) have naturally
to be connected to the power-ground and located
as close as possible to the Vs pins.
Pin 1, which is mechanically attached to the device’s tab, needs to be tied to the cleanest power
ground point in the pc-board, which is generally
near the supply filtering capacitors.
TDA7385
DIM.
A
B
C
D
E
F (1)
G
G1
H (2)
H1
H2
H3
L (2)
L1
L2 (2)
L3
L4
L5
M
M1
N
O
R
R1
R2
R3
R4
V
V1
V2
V3
MIN.
4.45
1.80
0.75
0.37
0.80
23.75
28.90
22.07
18.57
15.50
7.70
3.70
3.60
mm
TYP.
4.50
1.90
1.40
0.90
0.39
1.00
24.00
29.23
17.00
12.80
0.80
22.47
18.97
15.70
7.85
5
3.5
4.00
4.00
2.20
2
1.70
0.5
0.3
1.25
0.50
MAX.
4.65
2.00
MIN.
0.175
0.070
1.05
0.42
0.57
1.20
24.25
29.30
0.029
0.014
0.031
0.935
1.138
22.87
19.37
15.90
7.95
0.869
0.731
0.610
0.303
4.30
4.40
0.145
0.142
inch
TYP.
0.177
0.074
0.055
0.035
0.015
0.040
0.945
1.150
0.669
0.503
0.031
0.884
0.747
0.618
0.309
0.197
0.138
0.157
0.157
0.086
0.079
0.067
0.02
0.12
0.049
0.019
MAX.
0.183
0.079
OUTLINE AND
MECHANICAL DATA
0.041
0.016
0.022
0.047
0.955
1.153
0.904
0.762
0.626
0.313
0.169
0.173
5° (Typ.)
3° (Typ.)
20° (Typ.)
45° (Typ.)
Flexiwatt25
(1): dam-bar protusion not included
(2): molding protusion included
H
H1
V3
A
H2
O
H3
R3
L4
R4
V1
R2
L2
N
L3
R
L
L1
V1
V2
R2
D
R1
L5
R1
R1
E
G
V
G1
F
M
M1
B
C
V
FLEX25ME
11/12
TDA7385
Information furnished is believed to be accurate and reliable. However, STMicroelectronics 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 STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
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 1999 STMicroelectronics – Printed in Italy – All Rights Reserved
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