# Help with thermal fuse current definitions

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#### iliya24

##### Member level 2
Hello.

Trip Current and Hold Current?

Thx.

#### tpetar

Trip Current TC is minimal current which will activate fuse, and holding current is current which fuse allowing to pass without burning out. Also there should be tripind duration time in ms.

#### honey 77

Maximum current a fuse will pass without interruption is called hold current and minimum current that will trip a fuse iscalled trip current.

iliya24

### iliya24

Points: 2

#### iliya24

##### Member level 2
Hello Thx for help can u also help to understedn how to calculate Pw dissipation on LDO ?

#### ZekeR

##### Full Member level 5
Calculating the power dissipation of an LDO is very simple: You simply need to know Vin (voltage suppled TO the LDO), Vout (voltage suppled FROM the LDO), and Iout (current suppled by the LDO). The power dissipated will simply be (Vin - Vout) * Iout.

If you want a more precise calculation (this becomes useful for calculating the power loss during standby), you should take into account the LDO's quiescent current (the current it draws regardless of the output current; this is typically called Iq). Then the power dissipation becomes:
Pw = (Vin - Vout) * Iout + Vin * Iq.

Typically, Vin * Iq is a very small amount of power, so when you're drawing lots of current it becomes negligible compared with (Vin - Vout) * Iout. Under heavy loads, Vin * Iq can be ignored.

Hope this helps!

iliya24

Points: 2