TDA8943 데이터 시트보기 (PDF) - Philips Electronics

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TDA8943

6 W mono Bridge Tied Load (BTL) audio amplifier

Philips Electronics 

Philips Semiconductors

TDA8943SF

6 W mono Bridge Tied Load (BTL) audio amplifier

14.2 Thermal behaviour and heatsink calculation

The measured maximum thermal resistance of the IC package, Rth(j-mb) is 18 K/W.

A calculation for the heatsink can be made, with the following parameters:

Tamb(max) = 50 °C

VCC = 12 V and RL = 8 Ω

Tj(max) = 150 °C.

Rth(tot) is the total thermal resistance between the junction and the ambient

including the heatsink. In the heatsink calculations the value of Rth(mb-h) is ignored.

At VCC = 12 V and RL = 8 Ω the measured worst-case sine-wave dissipation is 3.8 W;

see Figure 11. For Tj(max) = 150 °C the temperature raise – caused by the power

dissipation – is: 150 – 50 = 100 °C.

P × Rth(tot) = 100 °C

Rth(tot) = 100/3.8 = 26.3 K/W

Rth(h-a) = Rth(tot) – Rth(j-mb) = 26.3 – 18 = 8.3 K/W.

The calculation above is for an application at worst-case 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 × Rth(tot) = 100 °C

Rth(tot) = 100/1.8 = 55.5 K/W

Rth(h-a) = Rth(tot) – Rth(j-mb) = 55.5 – 18 = 37.5 K/W.

To increase the lifetime of the IC, Tj(max) should be reduced to 125 °C. This requires a

heatsink of approximately 24 K/W for music signals.

15. Test information

15.1 Quality information

The General Quality Specification for Integrated Circuits, SNW-FQ-611D is

applicable.

15.2 Test conditions

Tamb = 25 °C; VCC = 12 V; f = 1 kHz; RL = 8 Ω; audio pass band 22 Hz to 22 kHz;

unless otherwise specified.

Remark: In the graphs as function of frequency no bandpass filter was applied; see

Figure 7 and 12.

9397 750 06865

Product specification

Rev. 02 — 7 April 2000

© Philips Electronics N.V. 2000. All rights reserved.

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