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TDA8542TS

2 x 0.7 W BTL audio amplifier

Philips Electronics 

Philips Semiconductors

2 × 0.7 W BTL audio amplifier

Product specification

TDA8542TS

TEST AND APPLICATION INFORMATION

Test conditions

Because the application can be either Bridge-Tied Load

(BTL) or Single-Ended (SE), the curves of each application

are shown separately.

The thermal resistance = 110 K/W for the SSOP20; the

maximum sine wave power dissipation for Tamb = 25 °C is:

1----5---10---1--–--0---2---5-- = 1.14 W

For Tamb = 60 °C the maximum total power dissipation is:

1----5---10---1--–--0---6---0-- = 0.82 W

Thermal design considerations

The ‘measured’ thermal resistance of the IC package is

highly dependent on the configuration and size of the

application board. Data may not be comparable between

different semiconductor manufacturers because the

application boards and test methods are not (yet)

standardized. Also, the thermal performance of packages

for a specific application may be different than presented

here, because the configuration of the application boards

(copper area) may be different. Philips Semiconductors

uses FR-4 type application boards with 1 oz copper traces

with solder coating.

The SSOP package has improved thermal conductivity

which reduces the thermal resistance. Using a practical

PCB layout (see Fig.22) with wider copper tracks to the

corner pins and just under the IC, the thermal resistance

from junction to ambient can be reduced to approximately

80 K/W. For Tamb = 60 °C the maximum total power

dissipation for this PCB layout is: 1----5---0--8---0–-----6---0-- = 1.12 W

function of frequency was measured with a low-pass filter

of 80 kHz. The value of capacitor C3 influences the

behaviour of the SVRR at low frequencies, increasing the

value of C3 increases the performance of the SVRR.

The figure of the mode select voltage (Vms) as a function

of the supply voltage shows three areas; operating, mute

and standby. It shows, that the DC-switching levels of the

mute and standby respectively depends on the supply

voltage level.

SE application

Tamb = 25°C if not specially mentioned, VCC = 7.5 V,

f = 1 kHz, RL = 4 Ω, Gv = 20 dB, audio band-pass

22 Hz to 22 kHz.

The SE application diagram is illustrated in Fig.14.

If the BTL/SE pin (pin 6) is connected to ground, the

positive outputs (pins 3 and 8) will be in mute condition

with a DC level of 1⁄2VCC. When a headphone is used

(RL ≥ 25 Ω) the SE headphone application can be used

without output coupling capacitors; load between negative

output and one of the positive outputs (e.g. pin 3) as

common pin. The channel separation will be less in

comparison with the application using a coupling capacitor

connected to ground.

Increasing the value of electrolytic capacitor C3 will result

in a better channel separation. Because the positive output

is not designed for high output current (2 × Io) at low load

impedance (≤16 Ω), the SE application with output

capacitors connected to ground is advised. The capacitor

value of C4/C5 in combination with the load impedance

determines the low frequency behaviour. The THD as a

function of frequency was measured using a low-pass filter

of 80 kHz. The value of capacitor C3 influences the

behaviour of the SVRR at low frequencies, increasing the

value of C3 increases the performance of the SVRR.

BTL application

Tamb = 25°C if not specially mentioned, VCC = 5 V,

f = 1 kHz, RL = 8 Ω, Gv = 20 dB, audio band-pass

22 Hz to 22 kHz.

The BTL application diagram is illustrated in Fig.3.

The quiescent current has been measured without any

load impedance. The total harmonic distortion as a

General remark

The frequency characteristic can be adapted by

connecting a small capacitor across the feedback resistor.

To improve the immunity of HF radiation in radio circuit

applications, a small capacitor can be connected in

parallel with the feedback resistor (56 kΩ); this creates a

low-pass filter.

1998 Mar 25

8

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