Stacked inductor keeps regulator cool

-December 26, 2016

A 40-A step-down switching regulator, the LTM4636 from Linear Technology delivers 40 W with only a 40°C rise over ambient temperature (12 VIN, 1 VOUT, 40 A, 200 LFM). By stacking its inductor on top of a 16×16-mm BGA package, the LTM4636 benefits from the exposed inductor as a heat sink, permitting direct contact with airflow from any direction to cool the device. Full power (40 W) is furnished at up to 83°C ambient, and half power (20 W) is supplied at up to 110°C ambient.

The µModule regulator operates at 92%, 90%, and 88% efficiency providing 15 A, 30 A, and 40 A, respectively, to a 1-V load (12 VIN). Parallel current sharing with four LTM4636 devices enables 160 W to be produced with only a 40°C rise and 88% efficiency (12 VIN, 1 VOUT, 400 LFM). The LTM4636 operates from a 4.7-V to 15-V input supply and regulates an output voltage from 0.6 V to 3.3 V. Total DC accuracy is ±3% from -40°C to +125°C.

Device height is 7.07 mm, including the stacked inductor. In addition to dissipating heat from the top, the LTM4636 uniformly disperses heat from the bottom of the package to the PCB with 144 BGA solder balls. Switching frequency ranges from 250 kHz to 770 kHz, while typical operating frequency is 400 kHz.

Prices for the LTM4636 start at $38.85 in lots of 1000 units.

LTM4636 product page

Linear Technology,

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