CS44130 datasheet(22/23 Pages) CIRRUS

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DS690PP1

CS44130

9. THERMAL CHARACTERISTICS

θJA is stated for a system with a thermal flag as described in Section 9.1 below.

9.1

Thermal Flag

This device is designed to have the metal flag on the bottom of the device soldered directly to a metal plane on the

PCB. To enhance the thermal dissipation capabilities of the system, this metal plane should be coupled with vias to

a large metal plane on the backside (and inner ground layer, if applicable) of the PCB.

In either case, it is beneficial to use copper fill in any unused regions inside the PCB layout, especially those imme-

diately surrounding the CS44130. In addition to improving in electrical performance, this practice also aids in heat

dissipation.

The heat dissipation capability required of the metal plane for a given output power can be calculated as follows:

TCA = [(TJ(MAX) - TA) / PD] - θJC

where,

TCA = Thermal resistance of the metal plane in °C/Watt

TJ(MAX) = Maximum rated operating junction temperature in °C, equal to 150 °C

TA = Ambient temperature in °C

PD = RMS power dissipation of the device, equal to 0.10*PRMS (assuming 90% efficiency)

θJC = Junction-to-case thermal resistance of the device in °C/Watt

Parameter

Symbol

Min

Typ

Max

Units

Junction to Case Thermal Impedance

θJC

-1

°C/Watt

Junction to Ambient Thermal Impedance

(Note 1)

2-Layer PCB

4-Layer PCB

θJA

18.5

°C/Watt

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