Philips Semiconductors
TFA9842J
2-channel audio amplifier (2 x SE or 1 x BTL)
Preliminary data Rev. 01 — 26 April 2004 15 of 21
9397 750 12013
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
13.1.2 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.
13.2 Thermal behavior and heatsink calculation
The measured maximum thermal resistance of the IC package, R
th(j-mb)
, 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
= 18 V and R
L
=4Ω (SE)
T
j(max)
= 150 °C (specification)
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
Fig 14. Printed-circuit board layout (single-sided); components view.
AUDIO POWER CS NIJMEGEN
27 Jan. 2003 / FP
IN2+ IN1+
MUTE
SB ON
TVA
TFA9843J
−SE2+
−SE1+
+V
P
1000 µF
1000 µF
1000 µF
BTL1/2
1
22
µF
10 kΩ
10
kΩ
MCE506
100 nF
150 µF
220
nF
220
nF
MODE
SGND
SVR
SVR
CIV
CIV
