WM8959 Wolfson Microelectronics Ltd., WM8959 Datasheet - Page 9

• Manufacturer Part Number: WM8959
• Description: Mobile Multimedia DAC with Dual-mode Class AB/D Speaker Driver
• Manufacturer: Wolfson Microelectronics Ltd.

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Pre-Production
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 Ө
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.
Figure 2 Class D Speaker Power De-Rating Curve
[W]
P
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
SPKVDD = 3.6V
SPKVDD = 3.3V
SPKVDD = 2.7V
SPKVDD = 3V
SPKVDD = 5.5V
55
60
65
SPKVDD = 5V
70
75
JA
SPKVDD = 4.2V
limit the amount of power that can
80
85
PP, May 2008, Rev 3.1
[ºC]
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WM8959
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