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TFA9842BJ/N1,112

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17
9397 750 12847 © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Preliminary data sheet Rev. 01 — 1 March 2004 10 of 17
Philips Semiconductors
TFA9842BJ
2-channel auto amplifier (2 × SE)
13. Application information
13.1 Application diagram
Remark: Switching inductive loads, the output voltage can rise beyond the maximum
supply voltage of 28 V. At high supply voltage it is recommended to use (Schottky) diodes
to the supply voltage and ground.
13.2 Printed-circuit board
13.2.1 Layout and grounding
To obtain a high-level system performance, certain grounding techniques are essential.
The input reference grounds have to be tied with their respective source grounds and
must have separate tracks from the power ground tracks; this will prevent the large
(output) signal currents from interfering with the small AC input signals. The small-signal
ground tracks should be physically located as far as possible from the power ground
tracks. Supply and output tracks should be as wide as possible for delivering maximum
output power.
Fig 12. Application diagram.
001aaa448
60
kΩ
60
kΩ
220 nF
STANDBY
MUTE
ON
SHORT-CIRCUIT
AND
TEMPERATURE
PROTECTION
V
REF
0.5V
CC
V
CC
V
CC
9
4
IN1
IN2
OUT1
OUT2
CIV
MODE
1
3
7
SVR
6
8
2
5
GND
TFA9842BJ
V
i
220 nF
V
i
V
CC
1000 µF
470 µF
470 µF
100 nF
R
L
4 Ω
+
−
R
L
4 Ω
−
+
V
CC
2.2
µF
10
kΩ
50
kΩ
270 Ω
BC547
BC547
7.5 V
micro-
controller
47
µF
22
µF
1.5
kΩ
100
kΩ
9397 750 12847 © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Preliminary data sheet Rev. 01 — 1 March 2004 11 of 17
Philips Semiconductors
TFA9842BJ
2-channel auto amplifier (2 × SE)
13.2.2 Power supply decoupling
Proper supply bypassing is critical for low-noise performance and high supply voltage
ripple rejection. The respective capacitor location should be as close as possible to the
device and grounded to the power ground. Proper power supply decoupling also prevents
oscillations.
For suppressing higher frequency transients (spikes) on the supply line a capacitor with
low ESR, typical 100 nF, has to be placed as close as possible to the device. For
suppressing lower frequency noise and ripple signals, a large electrolytic capacitor, e.g.
1000 µF or greater, must be placed close to the device.
The bypass capacitor on pin SVR reduces the noise and ripple on the mid rail voltage. For
good THD and noise performance a low ESR capacitor is recommended.
13.3 Thermal behavior and heatsink calculation
The measured maximum thermal resistance of the IC package, R
th(j-c)
, is 2.0 K/W.
A calculation for the heatsink can be made, with the following parameters:
T
amb(max)
=60°C (example)
V
CC
= 17 V and R
L
=4Ω
T
j(max)
= 150 °C (specification).
Fig 13. Printed-circuit board layout (single-sided); components view.
AUDIO POWER CS NIJMEGEN
27 Jan. 2003 / FP
IN2+ IN1+
MUTE
SB ON
TVA
−SE2+
−SE1+
+V
P
1000 µF
1000 µF
1000 µF
BTL1/2
1
22
µF
10 kΩ
10
kΩ
001aaa426
100 nF
150 µF
220
nF
220
nF
MODE
SGND
SVR
SVR
CIV
CIV
9397 750 12847 © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Preliminary data sheet Rev. 01 — 1 March 2004 12 of 17
Philips Semiconductors
TFA9842BJ
2-channel auto amplifier (2 × SE)
R
th(tot)
is the total thermal resistance between the junction and the ambient including the
heatsink. This can be calculated using the maximum temperature increase divided by the
power dissipation:
R
th(tot)
=(T
j(max)
− T
amb(max)
)/P
D
.
At V
CC
= 17 V and R
L
=4Ω (2 × SE) the measured worst-case sine-wave dissipation is
8.4 W (see Figure 9). For T
j(max)
= 150 °C the temperature raise, caused by the power
dissipation, is: 150 − 60=90°C:
P × R
th(tot)
=90°C
R
th(tot)
= 90/8.4 = 10.7 K/W
R
th(h-a)
=R
th(tot)
− R
th(j-c)
= 10.7 − 2.0 = 8.7 K/W.
This calculation is for an application at worst-case (stereo) sine-wave output signals. In
practice music signals will be applied, which decreases the maximum power dissipation to
approximately half of the sine-wave power dissipation (see Section 8.2.2). This allows for
the use of a smaller heatsink:
P × R
th(tot)
=90°C
R
th(tot)
= 90/4.2 = 21.4 K/W
R
th(h-a)
=R
th(tot)
− R
th(j-c)
= 21.4 − 2.0 = 19.4 K/W.
14. Test information
14.1 Quality information
The
General Quality Specification for Integrated Circuits, SNW-FQ-611
is applicable.
2 × SE loads; T
amb
=25°C; external heatsink of 10 K/W; music signals.
Fig 14. Junction temperature as function of supply voltage for various loads.
8
150
100
50
0
12 28
V
CC
(V)
16 20 24
001aaa449
T
j
(°C)
4 Ω
R
L
= 2 Ω
6 Ω
8 Ω
16 Ω
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P17

TFA9842BJ/N1,112

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Manufacturer:
NXP Semiconductors
Description:
IC AMP AUDIO PWR 7.5W STER 9SIL
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