WM8959 datasheet(9/155 Pages) WOLFSON

Part #	WM8959

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

PDF	155 Pages

Scroll/Zoom	100%

Manufacturer	WOLFSON [Wolfson Microelectronics plc]

Direct Link	http://www.wolfsonmicro.com

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9 / 155 page

Pre-Production

WM8959

PP, May 2008, Rev 3.1

SPEAKER POWER DE-RATING CURVE

The speaker driver has been designed to drive a maximum of 1W into 8

Ω 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.

[W]

[ºC]

0.4

0.6

0.8

1.0

SPKVDD = 2.7V

SPKVDD = 3V

SPKVDD = 3.3V

SPKVDD = 3.6V

SPKVDD = 4.2V

SPKVDD = 5V

SPKVDD = 5.5V

0.9

0.7

0.3

0.5

0.1

0.2

Figure 2 Class D Speaker Power De-Rating Curve

WM8959 Datasheet(PDF) 9 Page - Wolfson Microelectronics plc