LP3981-12B5F POWER [Lowpower Semiconductor inc], LP3981-12B5F Datasheet - Page 7

• Manufacturer Part Number: LP3981-12B5F
• Description: 300mA,Ultra-low noise, Small Package Ultra-Fast CMOS LDO Regulator
• Manufacturer: POWER [Lowpower Semiconductor inc]

The power dissipation definition in device is :
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junction to ambient.
The maximum power dissipation can be calculated by
following formula :
Where TJ(MAX) is the maximum operation junction
temperature 125°C, TA is the ambient temperature and
the θJA is the junction to ambient thermal resistance. For
recommended operating conditions specification of
LP3981, where TJ(MAX) is the maximum junction
temperature of the die (125°C) and TA is the maximum
ambient temperature. The junction to ambient thermal
resistance (θJA is layout dependent) for Sot23-5 package
is 250°C/W.
PD(MAX) = (125°C−25°C) / 250 = 400mW (Sot23-5)
PD(MAX) = (125°C−25°C) / 165 = 606mW
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA.
LP3981 – 01 Ver. 1.1 Datasheet
PD = (VIN−VOUT) x IOUT + VIN x IQ
PD(MAX) = ( TJ(MAX) − TA ) /θJA
Feb.-2008
Preliminary Datasheet
Page 7 of 8
LP3981