Quote Originally Posted by psdayama

One needs big heatsink for this.
Your statement is not accurate.

1 Watt of power dissipation without heat sink is possible with a LM317HV/TO220.
Below you can see how to calculate the maximum allowable power dissipation without heat sink.

Best regards,

Luciano

Code:
How to calculate the maximum allowable power 
dissipation without heat sink:


PD MAX = TjMAX − TaMAX
         _____________
             Rja

PD MAX = Maximum Power Dissipation (Watt)


TjMAX = maximum junction temperature (°C) 
For the LM317HV the operating junction temperature range is 0°C to +125°C.


TaMAX = maximum ambient air temperature (°C) 
Room temperature or temperature inside enclosure.


Rja= thermal resistance from junction to ambient without heat sink (°C/W) 
For the LM317HV/TO220 is 50 °C/W.


Example ambient air temperature 45°C: 

125°C − 45°C
__________    =  1.6 Watt 
   50°C/W


With an ambient temperature of 45°C, the maximum power dissipation 
of the LM317HV / TO-220 without heat sink is 1.6 Watt.

With an ambient temperature of 75°C, the maximum power dissipation 
of the LM317HV / TO-220 without heat sink is 1 Watt.