cs4412 Cirrus Logic, Inc., cs4412 Datasheet - Page 21

• Manufacturer Part Number: cs4412
• Description: 30 W Quad Half-bridge Digital Amplifier Power Stage Logic
• Manufacturer: Cirrus Logic, Inc.

DS749A1
8. THERMAL CHARACTERISTICS
8.1
Junction to Case Thermal Impedance
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 CS4412. 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
where,
θ
T
T
P
ciency)
θ
CA
CA
JC
J(MAX)
A
D
= Ambient temperature in °C
= RMS power dissipation of the device, equal to 0.15*P
= Junction-to-case thermal resistance of the device in ° C/Watt
= [(T
= Thermal resistance of the metal plane in °C/W att
= Maximum rated operating junction temperature in °C, e qual to 150 °C
J(MAX)
- T
Parameter
A
) / P
D
] - θ
JC
Symbol
RMS-IN
θ
JC
or 0.176*P
Min
-
RMS-OUT
Typ
1
(assuming 85% effi-
Max
-
CS4412
°C/Watt
Units
21