biasing isolated current supply for an amplifier

[john23]

Hello ,I split the voltage drop between several regulators.
My biggest dillema is with the power issue
one regulator is 12V to 10V it supplies 350mA to an amplifier, so the regulator has 0.7W threw it.
Other regulator is (7.2-5V)*0.6A=1.2W

I am using DDPAK-5 package, given the photo from the data sheet , how can I know the proper conditions for this regulator not to burn?
Full Ltspice is attached.
Thanks.


https://www.analog.com/media/en/technical-documentation/data-sheets/hmc907apm5e.pdf

[Andree Henkel]

in the datasheet for LT1764 is written:
TJmax=150°C max Temperature of Junction (of Semiconductor); RthJA=30°C/W (written in datasheet with greek Theta instead of Rth) thermal resistance Junction to Ambient
at page 2: package information for the DPAK

caution: look into table, datasheet page 13: you need large copper area on your pcb the tab is thermally attached to, to achieve the above mentioned RthJA, this copper area basically is working as an equivalent to a heatsink you would attach the TO220 package to

example: if you have provided enough copper area for 30°C/W,
and if your ambient temp is 55°C and power dissipation in LT1764 is 1W, then
the junction temperature is 55°C + 1W*30°C/W = 85W, which would be well below 150°C