Philips TDA1563Q User manual

DATA SHEET
Product specification
Supersedes data of 1998 Jul 14
File under Integrated Circuits, IC01
2000 Feb 09
INTEGRATED CIRCUITS
TDA1563Q
2×25 W high efficiency car radio
power amplifier

2000 Feb 09 2
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
FEATURES
•Low dissipation due to switching from Single-Ended
(SE) to Bridge-Tied Load (BTL) mode
•Differential inputs with high Common Mode Rejection
Ratio (CMRR)
•Mute/standby/operating (mode select pin)
•Zero crossing mute circuit
•Load dump protection circuit
•Short-circuit safe to ground, to supply voltage and
across load
•Loudspeaker protection circuit
•Device switches to SE operation at excessive junction
temperatures
•Thermal protection at high junction temperature (170°C)
•Diagnostic information (clip detection and
protection/temperature)
•Clipping information can be selected between
THD = 2.5% or 10%
GENERAL DESCRIPTION
The TDA1563Q is a monolithic power amplifier in a
17-lead DIL-bent-SIL plastic power package. It contains
two identical 25 W amplifiers. The dissipation is minimized
by switching from SE to BTL mode when a higher output
voltage swing is needed. The device is primarily
developed for car radio applications.
QUICK REFERENCE DATA
ORDERING INFORMATION
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
VPsupply voltage DC biased 6 14.4 18 V
non-operating −−30 V
load dump −−45 V
IORM repetitive peak output current −−4A
I
q(tot) total quiescent current RL=∞−95 150 mA
Istb standby current −150µA
Z
i
input impedance 90 120 150 kΩ
Pooutput power RL=4Ω; EIAJ −38 −W
RL=4Ω; THD = 10% 23 25 −W
Vselclip RL=4Ω; THD = 2.5% 18 20 −W
Gvclosed loop voltage gain 25 26 27 dB
CMRR common mode rejection ratio f = 1 kHz; Rs=0Ω−80 −dB
SVRR supply voltage ripple rejection f = 1 kHz; Rs=0Ω45 65 −dB
∆VODC output offset voltage −−100 mV
αcs channel separation Rs=0Ω40 70 −dB
∆Gvchannel unbalance −−1dB
TYPE
NUMBER PACKAGE
NAME DESCRIPTION VERSION
TDA1563Q DBS17P plastic DIL-bent-SIL power package; 17 leads (lead length 12 mm) SOT243-1

2000 Feb 09 3
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
BLOCK DIAGRAM
handbook, full pagewidth
MGR173
+
−
+
−
+
−
+
−
MUTE
VI
VI
VI
IV
IV
VI
SLAVE
CONTROL
17
16
IN2+
3
CIN
IN2−
60
kΩ
60
kΩ
60
kΩ
60
kΩ
25 kΩVref
OUT2−
OUT2+
10
11
CSE
4
+
−+
−
+
−
+
−
MUTE
SLAVE
CONTROL
1
2
IN1+
IN1−
OUT1+
OUT1−
8
7
+
−
VP
STANDBY
LOGIC CLIP AND
DIAGNOSTIC
6121415
MODE SC DIAG CLIP GND
9
VP2
13
VP1
5
TDA1563Q
Fig.1 Block diagram.

2000 Feb 09 4
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
PINNING
SYMBOL PIN DESCRIPTION
IN1+ 1 non-inverting input 1
IN1−2 inverting input 1
CIN 3 common input
CSE 4 electrolytic capacitor for SE mode
VP1 5 supply voltage 1
MODE 6 mute/standby/operating
OUT1−7 inverting output 1
OUT1+ 8 non-inverting output 1
GND 9 ground
OUT2−10 inverting output 2
OUT2+ 11 non-inverting output 2
SC 12 selectable clip
VP2 13 supply voltage 2
DIAG 14 diagnostic: protection/temperature
CLIP 15 diagnostic: clip detection
IN2−16 inverting input 2
IN2+ 17 non-inverting input 2
handbook, halfpage
TDA1563Q
MGR174
IN1+
IN1−
CIN
CSE
VP1
MODE
OUT1−
OUT1+
GND
OUT2−
OUT2+
SC
VP2
DIAG
CLIP
IN2−
IN2+
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Fig.2 Pin configuration.

2000 Feb 09 5
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
FUNCTIONAL DESCRIPTION
The TDA1563Q contains two identical amplifiers with
differential inputs. At low output power (up to output
amplitudes of 3 V (RMS) at VP= 14.4 V), the device
operates as a normal SE amplifier. When a larger output
voltage swing is needed, the circuit switches to BTL
operation.
With a sine wave input signal, the dissipation of a
conventionalBTLamplifierupto2 Woutputpowerismore
than twice the dissipation of the TDA1563Q (see Fig.10).
In normal use, when the amplifier is driven with music-like
signals, the high (BTL) output power is only needed for a
smallpercentageofthetime. Assumingthata musicsignal
has a normal (Gaussian) amplitude distribution, the
dissipation of a conventional BTL amplifier with the same
output power is approximately 70% higher (see Fig.11).
The heatsink has to be designed for use with music
signals. With such a heatsink, the thermal protection will
disable the BTL mode when the junction temperature
exceeds 150 °C. In this case, the output power is limited to
5 W per amplifier.
The gain of each amplifier is internally fixed at 26 dB. With
the MODE pin, the device can be switched to the following
modes:
•Standby with low standby current (<50 µA)
•Mute condition, DC adjusted
•On, operation.
The information on pin 12 (selectable clip) determines at
which distortion figures a clip detection signal will be
generated at the clip output. A logic 0 applied to pin 12 will
select clip detection at THD = 10%, a logic 1 selects
THD = 2.5%. A logic 0 can be realised by connecting this
pin to ground. A logic 1 can be realised by connecting it to
Vlogic (see Fig.7) or the pin can also be left open. Pin 12
may not be connected to VPbecause its maximum input
voltage is 18 V (VP> 18 V under load dump conditions).
The device is fully protected against a short circuit of the
output pins to ground and to the supply voltage. It is also
protected against a short circuit of the loudspeaker and
against high junction temperatures. In the event of a
permanentshortcircuittogroundorthesupplyvoltage,the
output stage will be switched off, causing low dissipation.
With a permanent short circuit of the loudspeaker, the
output stage will be repeatedly switched on and off. In the
‘on’ condition, the duty cycle is low enough to prevent
excessive dissipation.
To avoid plops during switching from ‘mute’ to ‘on’ or from
‘on’ to ‘mute/standby’ while an input signal is present, a
built-in zero-crossing detector only allows switching at
zero input voltage. However, when the supply voltage
drops below 6 V (e.g. engine start), the circuit mutes
immediately, avoiding clicks from the electronic circuit
preceding the power amplifier.
The voltage of the SE electrolytic capacitor (pin 4) is kept
at 0.5VPby a voltage buffer (see Fig.1). The value of this
capacitor has an important influence on the output power
in SE mode. Especially at low signal frequencies, a high
value is recommended to minimize dissipation.
The two diagnostic outputs (clip and diag) are
open-collector outputs and require a pull-up resistor.
The clip output will be LOW when the THD of the output
signal is higher than the selected clip level (10% or 2.5%).
The diagnostic output gives information:
•about short circuit protection:
– When a short circuit (to ground or the supply voltage)
occurs at the outputs (for at least 10 µs), the output
stages are switched off to prevent excessive
dissipation. The outputs are switched on again
approximately 50 ms after the short circuit is
removed. During this short circuit condition, the
protection pin is LOW.
– When a short circuit occurs across the load (for at
least 10 µs), the output stages are switched off for
approximately50 ms.After this time, acheckismade
to see whether the short circuit is still present.
The power dissipation in any short circuit condition is
very low.
•during startup/shutdown, when the device is internally
muted.
•temperaturedetection:Thissignal(junctiontemperature
> 145°C) indicates that the temperature protection will
becomeactive. Thetemperaturedetection signalcanbe
used to reduce the input signal and thus reduce the
power dissipation.

2000 Feb 09 6
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
THERMAL CHARACTERISTICS
Note
1. The value of Rth(c-h) depends on the application (see Fig.3).
SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT
VPsupply voltage operating −18 V
non-operating −30 V
load dump; tr>2.5 ms −45 V
VP(sc) short-circuit safe voltage −18 V
Vrp reverse polarity voltage −6V
I
ORM repetitive peak output current −4A
P
tot total power dissipation −60 W
Tstg storage temperature −55 +150 °C
Tvj virtual junction temperature −150 °C
Tamb ambient temperature −40 −°C
SYMBOL PARAMETER CONDITIONS VALUE UNIT
Rth(j-c) thermal resistance from junction to case see note 1 1.3 K/W
Rth(j-a) thermal resistance from junction to ambient 40 K/W
Heatsink design
There are two parameters that determine the size of the
heatsink. The first is the rating for the virtual junction
temperature and the second is the ambient temperature at
which the amplifier must still deliver its full power in the
BTL mode.
With a conventional BTL amplifier, the maximum power
dissipation with a music-like signal (at each amplifier) will
be approximately two times 6.5 W.
Atavirtualjunctiontemperatureof150 °C and a maximum
ambient temperature of 65 °C, Rth(vj-c) = 1.3 K/W and
Rth(c-h) = 0.2 K/W, the thermal resistance of the heatsink
should be:
Comparedto aconventionalBTL amplifier,theTDA1563Q
has a higher efficiency. The thermal resistance of the
heatsink should be:
150 65–
2 6.5×
---------------------- 1.3–0.2–5 K/W=
150 65–
2 6.5×
---------------------- 1.3–0.2–5 K/W=
1.7 145 65–
2 6.5×
----------------------


1.3–0.2–9 K/W=
handbook, halfpage
3.6 K/W
0.6 K/W
3.6 K/W
virtual junction
OUT 1 OUT 1
case
3.6 K/W
0.6 K/W
3.6 K/W
OUT 2 OUT 2
MGC424
0.1 K/W
Fig.3 Thermal equivalent resistance network.

2000 Feb 09 7
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
DC CHARACTERISTICS
VP= 14.4 V; Tamb =25°C; measured in Fig.7; unless otherwise specified.
Notes
1. The circuit is DC biased at VP= 6 to 18 V and AC operating at VP=8to18V.
2. If the junction temperature exceeds 150 °C, the output power is limited to 5 W per channel.
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
Supplies
VPsupply voltage note 1 6 14.4 18 V
Iq(tot) total quiescent current RL=∞−95 150 mA
Istb standby current −150µA
V
Caverage electrolytic capacitor voltage at pin 4 −7.1 −V
∆VODC output offset voltage on state −−100 mV
mute state −−100 mV
Mode select switch (see Fig.4)
Vms voltage at mode select pin (pin 6) standby condition 0 −1V
mute condition 2 −3V
operating condition 4 5 VPV
Ims switch current through pin 6 Vms =5V −25 40 µA
Diagnostic
Vdiag output voltage at diagnostic outputs (pins 14 and
15): protection/temperature and detection during any fault condition −−0.5 V
Idiag current through pin 14 or 15 during any fault condition 2 −−mA
VSC input voltage at selectable clip pin (pin 12) clip detect at THD = 10% −−0.5 V
clip detect at THD = 2.5% 1.5 −18 V
Protection
Tpre prewarning temperature −145 −°C
T
dis(BTL) BTL disable temperature note 2 −150 −°C

2000 Feb 09 8
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
Fig.4 Switching levels of the mode select switch.
handbook, halfpage
MGR176
18
Vmode
4
3
2
1
0
Mute
Operating
Standby

2000 Feb 09 9
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
AC CHARACTERISTICS
VP= 14.4 V; RL=4Ω; CSE = 1000 µF; f = 1 kHz; Tamb =25°C; measured in Fig.7; unless otherwise specified.
Notes
1. The distortion is measured with a bandwidth of 10 Hz to 30 kHz.
2. Frequency response externally fixed (input capacitors determine low frequency roll-off).
3. The SE to BTL switch voltage level depends on VP.
4. Noise output voltage measured with a bandwidth of 20 Hz to 20 kHz.
5. Noise output voltage is independent of Rs.
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
Pooutput power THD = 0.5% 15 19 −W
THD = 10% 23 25 −W
EIAJ −38 −W
VP= 13.2 V; THD = 0.5% −16 −W
VP= 13.2 V; THD = 10% −20 −W
THD total harmonic distortion Po= 1 W; note 1 −0.1 −%
Pddissipated power see Figs 10 and 11 W
Bppower bandwidth THD = 1%; Po=−1dB
with respect to 15 W −20 to 15000 −Hz
fro(l) low frequency roll-off −1 dB; note 2 −25 −Hz
fro(h) high frequency roll-off −1 dB 130 −−kHz
Gvclosed loop voltage gain Po= 1 W 25 26 27 dB
SVRR supply voltage ripple rejection Rs=0Ω; Vripple = 2 V (p-p)
on/mute 45 65 −dB
standby; f = 100 Hz to 10 kHz 80 −−dB
CMRR common mode rejection ratio Rs=0Ω−80 −dB
Ziinput impedance 90 120 150 kΩ
∆Zimismatch in input impedance −1−%
VSE-BTL SE to BTL switch voltage level note 3 −3−V
Vo(mute)output voltage mute (RMS value) Vi= 1 V (RMS) −100 150 µV
Vn(o) noise output voltage on; Rs=0Ω; note 4 −100 150 µV
on; Rs=10kΩ; note 4 −105 −µV
mute; note 5 −100 150 µV
αcs channel separation Rs=0Ω; Po=15W 40 70 −dB
∆Gvchannel unbalance −− 1dB

2000 Feb 09 10
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
Fig.5 Clip detection waveforms.
handbook, halfpage
MGR177
Vo
CLIP
0
0
t
Fig.5 Clip detection waveforms. Fig.6 Protection waveforms.
handbook, halfpage
MGR178
maximum current short circuit to supply pins
short circuit
to ground
short circuit
removed
50
ms
50
ms
50
ms
10 µs
Io
DIAG
0
max
max
t
t

2000 Feb 09 11
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
TEST AND APPLICATION INFORMATION
handbook, full pagewidth
MGR180
3CIN 25 kΩ
60
kΩ60 kΩ
60
kΩ60 kΩ
Vref
OUT2−
OUT2+
10
11
CSE
4
2IN1−
1IN1+OUT1+
OUT1−
8
7
STANDBY
LOGIC CLIP AND
DIAGNOSTIC
6121415
MODE SC DIAG CLIP
9
GND
VP2
13
VP1
5
TDA1563Q
1 µF1000 µF
220 nF
0.5Rs
220 nF
0.5Rs
+
−
+
−
Vms
VP
Vlogic
Rpu
Rpu
10%
2.5%
16IN2−
17IN2+
220 nF
0.5Rs
100 nF
100 nF
3.9 Ω
4 Ω
3.9 Ω
100 nF
100 nF
3.9 Ω
4 Ω
3.9 Ω
220 nF
0.5Rs
+
−
+
−
220 nF 2200 µF
signal ground
power ground
Fig.7 Application diagram.
Connect Boucherot filter to pin 8 or pin 10 with the shortest possible connection.

2000 Feb 09 12
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, full pagewidth
76.20
35.56
TDA1563Q
RL-98
MGR189
+
−
Out2 +
−
Out2
+
−
In2
+
−
In1
Clip
Vp GND
gnd gnd
Prot
2.5%
10%
Mode Mute
On
Off
Clip
Fig.8 PCB layout (component side) for the application of Fig.7.
Dimensions in mm.

2000 Feb 09 13
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, full pagewidth
76.20
35.56
MGR190
Vp
GND
2×25 W high efficiency
1 µF
1
17
Out2 Out1
In1
In2
220 nF 220 nF 220 nF
Fig.9 PCB layout (soldering side) for the application of Fig.7.
Dimensions in mm.

2000 Feb 09 14
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, halfpage
010
P
o
(W)
25
0
5
10
15
20
2
Pd
(W)
468
MBH692
(1)
(2)
Fig.10 Dissipation; sine wave driven.
Input signal 1 kHz, sinusoidal; VP= 14.4 V.
(1) For a conventional BTL amplifier.
(2) For TDA1563Q.
handbook, halfpage
010
P
o
(W)
25
0
5
10
15
20
2
Pd
(W)
468
MBH693
(1)
(2)
Fig.11 Dissipation; pink noise through IEC-268
filter.
(1) For a conventional BTL amplifier.
(2) For TDA1563Q.
430 Ω
input output
330 Ω
3.3
kΩ
3.3
kΩ10 kΩ
91
nF 68 nF
470 nF2.2 µF 2.2 µF
MGC428
Fig.12 IEC-268 filter.

2000 Feb 09 15
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, full pagewidth
MGR181
3CIN 25 kΩ
60
kΩ60 kΩ
60
kΩ60 kΩ
Vref
OUT2−
OUT2+
10
11
CSE
4
2IN1−
1IN1+OUT1+
OUT1−
8
7
STANDBY
LOGIC CLIP AND
DIAGNOSTIC
6121415
MODE SC DIAG CLIP
VP2
13
VP1
5
TDA1563Q
1 µF1000 µF
220 nF
220 nF
IEC-268
FILTER
pink
noise
+
−
+
−
Vms
VP
Vlogic
Rpu
Rpu
16IN2−
17IN2+
220 nF
100 nF
100 nF
3.9
Ω
4 Ω
3.9 Ω
100 nF
100 nF
3.9
Ω
4 Ω
3.9 Ω
220 nF
+
−
+
−
220 nF 2200 µF
signal ground
power ground
9
GND
Fig.13 Test and application diagram for dissipation measurements with a music-like signal (pink noise).

2000 Feb 09 16
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, halfpage
0
150
100
50
08Vp(V)
Iq
(mA)
2416
MDA845
Fig.14 Quiescent current as a function of VP.
Vms = 5 V; RI=∞.
handbook, halfpage
02 V
ms (V)
Ip
(mA)
46
250
0
200
150
100
50
MDA844
Fig.15 IPas a function of Vms (pin 3).
VP= 14.4 V; Vi=25mV
handbook, halfpage
818
60
0
20
40
10
Po
(W)
Vp(V)
12 14 16
MDA843
(1)
(2)
(3)
Fig.16 Output power as a function of VP.
(1) EIAJ, 100 Hz.
(2) THD = 10 %.
(3) THD = 0.5 %.
handbook, halfpage
10
1
10−1
10−1
10−2
10−2
MDA842
110
THD + N
(%)
102
(1)
(2)
(3)
Po (W)
Fig.17 THD + noise as a function of Po.
(1) f = 10 kHz.
(2) f = 1 kHz.
(3) f = 100 Hz.

2000 Feb 09 17
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, halfpage
10
1
10−1
10−2
MDA841
10 102103104
THD + N
(%)
f (Hz) 105
(1)
(2)
Fig.18 THD + noise as a function of frequency.
(1) Po=10W.
(2) Po=1W.
handbook, halfpage
20
22
24
26
Gv
(dB)
f (Hz)
28
MDA840
10 102103104105106
Fig.19 Gain as a function of frequency.
Vi= 100 mV.
handbook, halfpage
−90
−70
−50
−30
−10
MDA838
10 f (Hz)
αcs
(dB)
102103104105
(1)
(2)
Fig.20 Channel separation as a function of
frequency.
(1) Po=10W.
(2) Po=1W.
handbook, halfpage
−80
−60
−40
−20
0
MDA839
10 f (Hz)
SVRR
(dB)
102103104105
Fig.21 SVRR as a function of frequency.
Vripple(p-p) =2V.

2000 Feb 09 18
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, halfpage
08 V
p
(V)
Po
(W)
24
0.8
0.6
0.2
0
0.4
16
MDA846
Fig.22 AC operating as a function of VP.
Vi=70mV.

2000 Feb 09 19
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
handbook, full pagewidth
MGL914
0 1 2 t (ms) 3
1/2 VP
1/2 VP
0
−VP
VP
VP
0
VP
Vload
Vmaster
Vslave
0
Fig.23 Output waveforms.
See Fig.7:
Vload =V
7−V 8
or V11 −V10
Vmaster =V
7or V11
Vslave =V
8or V10

2000 Feb 09 20
Philips Semiconductors Product specification
2×25 W high efficiency car radio power
amplifier TDA1563Q
APPLICATION NOTES
Example of the TDA1563Q in a car radio system
solution
The PCB shown here is used to demonstrate an audio
system solution with Philips Semiconductors devices for
caraudio applications.Theboard includestheSAA7705H:
a high-end CarDSP (Digital Signal Processor), the
TDA3617J: a voltage regulator providing 9 V, 5 V and
3.3 V outputs, and two TDA1563Qs to provide four 25 W
power outputs. A complete kit (application report, software
and demo board) of this “car-audio chip-set demonstrator”
is available.
The TDA1563Q is a state of the art device, which is
different to conventional amplifiers in power dissipation
because it switches between SE mode and conventional
BTL mode, depending on the required output voltage
swing. As a result, the PCB layout is more critical than with
conventional amplifiers.
NOTES AND LAYOUT DESIGN RECOMMENDATIONS
1. The TDA1563Q mutes automatically during switch-on
and switch-off and suppresses biasing clicks coming
fromtheCarDSPcircuit precedingthepoweramplifier.
Therefore, it is not necessary to use a plop reduction
circuit for the CarDSP. To mute or to enlarge the mute
time of the system, the voltage at the mode pin of the
amplifiers should be kept between 2 V and 3 V.
2. The input reference capacitor at pin 3 is specified as
1µF but has been increased to 10 µF to improve the
switch-onplopperformanceoftheamplifiers.Bydoing
this, the minimum switch-on time increases from
standby,viainternal mute, to operatingfrom150 msto
600 ms.
3. It is important that the copper tracks to and from the
electrolytic capacitors (SE capacitors and supply
capacitors) are close together. Because of the
switching principle, switching currents flow here.
Combining electrolytic capacitors in a 4-channel
application is not recommended.
4. Filters at the outputs are necessary for stability
reasons. The filters at output pins 8 and 10 to ground
should be connected as close as possible to the
device (see layout of PCB).
5. Connect the supply decoupling capacitors of 220 nF
as closely as possible to the TDA1563Qs.
6. Place the tracks of the differential inputs as close
togetheras possible.Ifdisturbances areinjectedat the
inputs, they will be amplified 20 times. Oscillation may
occur if this is not done properly.
7. The SE line output signal of the CarDSP here is
offered as a quasi differential input signal to the
amplifiers by splitting the 100 Ωunbalance series
resistance into two 47 Ωbalanced series resistances.
Thereturntrackfrom the minus inputs of the amplifiers
are not connected to ground (plane) but to the line out
reference voltage of the CarDSP, VrefDA.
8. The output signal of the CarDSP needs an additional
1st order filter. This is done by the two balanced series
resistances of 47 Ω(see note 7) and a ceramic
capacitor of 10 nF. The best position to place these
10 nF capacitors is directly on the input pins of the
amplifiers.Now,anyhighfrequencydisturbanceat the
inputs of the amplifiers will be rejected.
9. Only the area underneath the CarDSP is a ground
plane. A ground plane is necessary in PCB areas
where high frequency digital noise occurs. The audio
outputs are low frequency signals. For these outputs,
itis bettertousetwotracks (feedandreturn)asclosely
as possible to each other to make the disturbances
common mode. The amplifiers have differential inputs
with a very high common mode rejection.
10. The ground pin of the voltage regulator is the
reference for the regulator outputs. This ground
reference should be connected to the ground plane of
the CarDSP by one single track. The ground plane of
theCarDSPmaynotbeconnectedto“another”ground
by a second connection.
11. Prevent power currents from flowing through the
ground connection between CarDSP and voltage
regulator. The currents in the ground from the
amplifiers are directly returned to the ground pin of the
demo board. By doing this so, no ground interference
between the components will occur.