AMC7135 Datasheet, PDF (4/6 Pages) ADDtek Corp – 350mA ADVANCED CURRENT REGULATOR

AMC7135
APPLICATION INFORMATION
The Maximum Power Dissipation on Regulator:
P_D(MAX) = V_OUT(MAX) × I_OUT(NOM) + V_IN(MAX) × I_Q
V_OUT(MAX) = the maximum voltage on output pin;
I_OUT(NOM) = the nominal output current;
I_Q = the quiescent current the regulator consumes at I_OUT(MAX);
V_IN(MAX) = the maximum input voltage.
Thermal Consideration:
The maximum junction temperature ratings of AMC7135 should not be exceeded under continuous normal load
conditions. When power consumption is over about 700mW (SOT-89 package, at T_A=70°C) or 1000mW (TO-252
package, at T_A=70°C), additional heat sink is required to control the junction temperature below 120°C.
The junction temperature is:
T_J = P_D (θ_JT +θ_CS +θ_SA ) + T_A
P_D : Dissipated power.
θ_JT: Thermal resistance from the junction to the mounting tab of the package.
θ_CS: Thermal resistance through the interface between the IC and the surface on which it is mounted.
(typically, θ_CS < 1.0°C /W)
θ_SA: Thermal resistance from the mounting surface to ambient (thermal resistance of the heat sink).
If PC Board copper is going to be used as a heat sink, below table can be used to determine the appropriate size
of copper foil required. For multi-layered PCB, these layers can also be used as a heat sink. They can be connected with
several through-hole vias.
PCB θSA (°C /W)
59
PCB heat sink size (mm²) 500
45
1000
38
1500
33
2000
27
3000
24
4000
21
5000
Copyright © 2007 ADDtek Corp.
4
DD031_C -- APRIL 2007