TFA9842AJ Philips, TFA9842AJ Datasheet - Page 5

• Manufacturer Part Number: TFA9842AJ
• Description: 7.5W Stereo Power Amplifier
• Manufacturer: Philips

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Philips Semiconductors
TFA9842AJ_1
Preliminary specification
8.2.2 Headroom
8.3 Mode selection
8.4 Supply voltage ripple rejection
Typical CD music requires at least 12 dB (factor 15.85) dynamic headroom, compared to
the average power output, for transferring the loudest parts without distortion. At
V
Listening Level (ALL) music power without any distortion yields:
The power dissipation can be derived from
headroom (see
For the average listening level a power dissipation of 4.2 W can be used for a heatsink
calculation.
Table 4.
The TFA9842AJ has four functional modes, which can be selected by applying the proper
DC voltage to pin VC (see
Table 5.
The supply voltage ripple rejection (SVRR) is measured with an electrolytic capacitor of
150 F connected to pin SVR with a bandwidth of 20 Hz to 22 kHz. The SVRR as a
function of the frequency is illustrated in
improves the ripple rejection behavior at the lower frequencies.
P
Headroom
0 dB
12 dB
V
0 V to 0.8 V
1.2 V to 1.5 V
1.5 V to 5.0 V
5.0 V to V
CC
o ALL
I(VC)
= 17 V and P
=
CC
Power rating as function of headroom
Mode selection
------------ -
15.85
5
Table
=
o
= 5 W (SE with R
315 mW
4).
Status
Standby
Mute
Volume control
On (maximum gain)
Rev. 01 — 28 April 2006
Table
Power output SE
(THD < 0.5 %)
P
P
o
o(ALL)
5).
= 5 W
L
= 315 mW
7.5 W stereo power amplifier with volume control
= 4 ) at THD < 0.5 % (see
Figure
Figure 8
Definition
in this mode the current consumption is very low
and the outputs are floating; the device is in
Standby mode when V
in this mode the amplifier is DC-biased but not
operational (no audio output); this allows the input
coupling capacitors to be charged to avoid
pop-noise; the device is in Mute mode when
1.2 V < V
in this mode the volume of the amplifier can be
controlled; the gain can be adjusted between the
range of 1.5 V < V
in this mode the amplifier has its maximum gain;
the Operating mode is activated at V
10. A larger capacitor value on pin SVR
I(VC)
(SE) for 0 dB respectively 12 dB
< 1.5 V.
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
I(VC)
Power dissipation (P);
both channels driven
8.4 W
4.2 W
I(VC)
< 5.0 V.
TFA9842AJ
Figure
< 0.8 V.
5), the Average
I(VC)
> 5.0 V.
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