Cirrus Logic CS35L03 - Manual (Page 31)

CS35L01/03
DS909F1 31
8.2 Recommend PCB Footprint and Routing Configuration
To ensure high-yield manufacturability, the PCB footprint for the CS35L01/03 should be constructed with
strict adherence to the specifications given in IPC-610. Departure from this specification significantly in-
creases the probability of solder bridging and other manufacturing defects.
Routing of the traces into and out of the CS35L01/03 device should also be given consideration to avoid
manufacturing issues.
8.3 Package Thermal Performance
Class-D amplifiers, though highly efficient, will produce some amount of heat through the process of ampli-
fying the audio signal. As is well understood, this amount of heat is very small compared to traditional Class
AB amplifiers. Even so, as power levels increase and package sizes decrease, careful consideration must
be given to ensure thermal energy is removed from the device as efficiently as possible so that its operating
temperature is kept under its Over-Temperature Error Threshold.
The thermal impedance, 
JA
is a measurement of the impedance to the flow of thermal energy out of the
device to the environment surrounding the device. This specification is directly related to the ability of the
PCB to which the CS35L01/03 is attached to transfer the heat from the device. The thermal impedance from
the junction of the device to the ambient surrounding the device and the thermal impedance from the device
into the PCB is shown in
Table 2 .
.
Table 2.

JA
Specification for Typical PCB Designs
Note:
21. Test Printed Circuit Board Assembly (PCBA) constructed in accordance with JEDEC standard
JESD51-9. Two signal, two plane (2s2p) PCB utilized.
22. Test conducted with still air in accordance with JEDEC standards JESD51, JESD51-2A, and
JESD51-8.
Parameter (Note 21) , (Note 22) Symbol Min Typical Max Units
Junction to Ambient Thermal Impedance 
A
- 92 - °C/Watt
Junction to Printed Circuit Board Thermal Impedance 
PCB
- 67 - °C/Watt