CS35L00 datasheet(32/34 Pages) CIRRUS

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CS35L00

DS906A2

8.4.1

Determining Maximum Ambient Temperature

To determine (to a first order approximation) the maximum ambient temperature in which the CS35L00

will operate, the following equations can be used:

Where:

Tmax = The maximum ambient temperature in which the device can operate.

Top = The operating temperature of the device, given a dissipated power “Pmax” and a known thermal

impedance “



JA”.

TTE = The Over-Temperature Error Threshold, given in the “Characteristics & Specifications” section on

page 8.



JA = The thermal impedance of the device and PCB. (This value is highly subjective to a number of ap-

plication specific scenarios. The numbers given in Table 2 on page 31 can be used for a first order ap-

proximation, but proper characterization of the application’s specific PCB and supporting mechanicals is

needed to increase the accuracy of the result achieved here.)

Pmax = The maximum power at which the amplifier will be operated continuously. (For conservative esti-

mates, the 10% THD+N rated power given in “Characteristics & Specifications” section on page 8 can be

used. However, this method will predict higher operating temperatures than what may be seen in the ap-

plication, since power content of audio signals is much smaller than that of the sine wave used to establish

the power specifications.)

= The efficiency of the device at the power Pmax. (A safe, conservative assumption is 85%)





–

 P



max





max

–

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