LP3972 datasheet(6/59 Pages) TI1

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LP3972

SNVS468J – SEPTEMBER 2006 – REVISED AUGUST 2011

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Operating Ratings

VIN

2.7V to 5.5V

VINLDO4, 5

1.74 to VIN

Junction Temperature (TJ)

−40°C to +125°C

Operating Temperature (TA)

−40°C to +85°C

Maximum Power Dissipation (TA = 70°C)

(1) (2)

2.2W

(1)

In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may

have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-

OP = 125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance

of the part/package in the application (

θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA x PD-MAX).

(2)

Junction-to-ambient thermal resistance (

θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set

forth in the JEDEC standard JESD51–7. The test board is a 4-layer FR-4 board measuring 102 mm x 76 mm x 1.6 mm with a 2x1 array

of thermal vias. The ground plane on the board is 50 mm x 50 mm. Thickness of copper layers are 36 µm/1.8 µm/18 µm/36 µm (1.5 oz/1

oz/1 oz/1.5 oz). Ambient temperature in simulation is 22°C, still air. Power dissipation is 1W. Junction-to-ambient thermal resistance is

highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid

to thermal dissipation issues in board design. The value of

θJA of this product can vary significantly, depending on PCB material, layout,

and environmental conditions. In applications where high maximum power dissipation exists (high VIN, high IOUT), special care must be

paid to thermal dissipation issues. For more information on these topics, see Application Note AN-1187 Leadless Leadframe Package

(LLP) and the Power Efficiency and Power Dissipation sections of this datasheet.

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