WM8959 Wolfson Microelectronics Ltd., WM8959 Datasheet - Page 8

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

WM8959
w
PARAMETER
Operating temperature range
Operating junction temperature
Thermal Resistance
THERMAL PERFORMANCE
Thermal analysis should be performed in the intended application to prevent the WM8959 from
exceeding maximum junction temperature. Several contributing factors affect thermal performance
most notably the physical properties of the mechanical enclosure, location of the device on the PCB
in relation to surrounding components and the number of PCB layers. Connecting the GND balls
through thermal vias and into a large ground plane will aid heat extraction.
Three main heat transfer paths exist to surrounding air as illustrated below in Figure 1:
Figure 1 Heat Transfer Paths
The temperature rise T
The junction temperature T
-
-
-
-
-
Package top to air (radiation).
Package bottom to PCB (radiation).
Package balls to PCB (conduction).
P
Ө
and is therefore a measure of heat transfer from the die to surrounding air. Ө
determined with reference to JEDEC standard JESD51-9.
D
JA
SYMBOL
is the power dissipated in the device.
is the thermal resistance from the junction of the die to the ambient temperature
Ө
T
T
JA
A
R
J
is given by T
J
is given by T
R
= P
J
D
= T
MIN
-40
-40
* Ө
A
JA
+T
R
, where T
TYP
43
A
is the ambient temperature.
MAX
100
85
PP, May 2008, Rev 3.1
Pre-Production
°C/W
UNIT
°C
°C
JA
is
8