MIC5311 Datasheet, PDF (10/11 Pages) Micrel Semiconductor – LowQ Mode Dual 300mA LDO

Micrel, Inc.
MIC5311
P_DTOTAL = P_{D LDO1} + P_{D LDO2}
P_DTOTAL = 360mW + 140mW
P_DTOTAL = 500mW
The calculation shows that we are well below the
maximum allowable power dissipation of 1.03W for a
60° ambient temperature.
After the maximum power dissipation has been
calculated, it is always a good idea to calculate the
maximum ambient temperature for a 125° junction
temperature. Calculating maximum ambient temperature
as follows:
T_A(max) = T_J(max) – (P_D x θ_JA)
T_A(max) = 125°C – (500mW x 63°C/W)
T_A(max) = 93.5°C
For a full discussion of heat sinking and thermal effects
on voltage regulators, refer to the “Regulator Thermals”
section of Micrel’s Designing with Low-Dropout Voltage
Regulators handbook.
This information can be found on Micrel's website at:
http://www.micrel.com/_PDF/other/LDOBk_ds.pdf
February 2005
10
M9999-021105
[phone]