CS3511
9. THERMAL CHARACTERISTICS
Parameter
Symbol
Min
Typ
Max
Units
Junction to Case Thermal Impedance
θJC
-
1
-
°C/Watt
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 cou-
pled 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
immediately surrounding the CS3511. 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:
θ
= [(T
- T ) / P ] - θ
J(MAX) A D JC
CA
where,
= Thermal resistance of the metal plane in °C/Watt
θ
CA
T
= Maximum rated operating junction temperature in °C, equal to 150 °C
J(MAX)
T = Ambient temperature in °C
A
P = RMS power dissipation of the device, equal to 0.176*P
(assuming 85% efficiency)
D
RMS-OUT
θ
= Junction-to-case thermal resistance of the device in °C/Watt, equal to 1 °C/Watt
JC
DS845PP2
23
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