IL1084-1.8BT2 Просмотр технического описания (PDF) - IK Semicon Co., Ltd

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IL1084-1.8BT2

5A LOW DROPOUT POSITIVE REGULATOR

IK Semicon Co., Ltd 

IL1084-xx

Once the devices power is determined, the maximum allowable (θJA (max)) is calculated as:

θJA (max) = TR(max)/PD = TJ(max) − TA(max)/PD

The IL1084 has different temperature specifications for two different sections of the IC: the control section and the output

section. The Electrical Characteristics table shows the junction to case thermal resistances for each of these sections, while the

maximum junction temperatures (TJ(max)) for each section is listed in the Absolute Maximum section of the datasheet. TJ(max) is

125°C for the control section, while TJ(max) is 150°C for the output section. θJA (max) should be calculated separately for each

section as follows:

θJA (max, CONTROL SECTION) = (125°C - TA(max))/PD

θJA (max, OUTPUT SECTION) = (150°C - TA(max))/PD

The required heat sink is determined by calculating its required thermal resistance (θHA (max)).

(θHA (max)) should also be calculated twice as follows:

(θHA (max)) = θJA (max, CONTROL SECTION) - (θJC (CONTROL SECTION) + θCH)

(θHA (max)) = θJA(max, OUTPUT SECTION) - (θJC (OUTPUT SECTION) + θCH)

If thermal compound is used, θCH can be estimated at 0.2 C/W. If the case is soldered to the heat sink, then a θCH can be

estimated as 0 C/W.

After, θHA (max) is calculated for each section, choose the lower of the two θHA (max) values to determine the appropriate

heat sink.

If PC board copper is going to be used as a heat sink, then Figure 7 can be used to determine the appropriate area (size)

of copper foil required.

FIGURE 7. Heat sink thermal Resistance vs Area

Rev. 04

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