WM8959 Ver la hoja de datos (PDF) - Wolfson Microelectronics plc

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WM8959

Mobile Multimedia DAC with Dual-Mode Class AB/D Speaker Driver

Wolfson Microelectronics plc 

Pre-Production

WM8959

SPEAKER POWER DE-RATING CURVE

The speaker driver has been designed to drive a maximum of 1W into 8Ω with a 5V supply.

However, thermal restrictions defined by the W-CSP package ӨJA limit the amount of power that can

be safely dissipated in the device without exceeding the maximum operating junction temperature.

Power dissipated in the device correlates directly with speaker efficiency, hence there are separate

de-rating curves for class D and class AB operation.

Under no circumstances should the recommended maximum powers be exceeded.

CLASS D DE-RATING CURVES

The de-rating curves shown in Figure 2 are based on a full scale sinusoidal input.

P

[W]

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

SPKVDD = 5.5V SPKVDD = 5V SPKVDD = 4.2V

SPKVDD = 3.6V

SPKVDD = 3.3V

SPKVDD = 3V

SPKVDD = 2.7V

55 60 65 70 75 80 85

T

[ºC]

Figure 2 Class D Speaker Power De-Rating Curve

w

PP, May 2008, Rev 3.1

9

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