1A L.D.O. VOLTAGE REGULATOR

LM1117S/RS/F

Maximum Output Current Capability

The LM1117 can deliver a continuous current of 1A over the full operating junction temperature range. However, the

current is limited by the restriction of power dissipation which differs from packages. A heat sink may be required

depending on the maximum power dissipation and maximum ambient temperature of application. With respect to th

applied package, the maximum output current of 1A may be still undeliverable due to the restriction of the power diss

of LM1117. Under all possible conditions, the junction temperature must be within the range specified under

operating conditions. The temperatures over the device are given by:

of the device, θCA is the thermal resistance of case-to-ambient, θJC is the thermal resistance of junction-to-case,

and θJA is the thermal resistance of junction to ambient. The total power dissipation of the device is given by

allowable temperature rise (TRmax) depends on the maximum ambient temperature (TAmax) of the application

and the maximum allowable junction temperature (TJmax):

LM1117 is available in SOT223, TO252 packages. The thermal resistance depends on amount of copper area or he

and on air flow. If the maximum allowable value of θJA calculated above is over 130°C/W for SO-223 package, over

for TO252 package, no heat sink is needed since the package can dissipate enough heat to satisfy these

requirements. If the value for allowable θJA falls near or below these limits, a heat sink or proper area of cop

plane is required. In summary, the absolute maximum ratings of thermal resistances are as follow:

Absolute Maximum Ratings of Thermal Resistance

No heat sink / No air flow / No adjacent heat source / 0.066 inch

Jan. 2007 - Rev 1.0

HTC

Max. Rating

Unit

Thermal Resistance Junction-To-Ambient / TO252

θJA-TO252

93

°C/W

Thermal Resistance Junction-To-Ambient / SOT223

θJA-SOT223

130

°C/W

Characteristic

Symbol

11

Thermal Resistance Junction-To-Ambient / SOT89

θJA-SOT89

315

°C/W