EN6340QI datasheet(21/28 Pages) INTEL

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Datasheet | Intel® Enpirion® Power Solutions: EN6340QI

Page 21

Figure 6: Efficiency vs. Output Current

For VIN = 5V, VOUT = 3.3V at 4A, η ≈ 94%

η = POUT / PIN = 94% = 0.94

PIN = POUT / η

PIN ≈ 13.2W / 0.94 ≈ 14W

The power dissipation (PD) is the power loss in the system and can be calculated by subtracting the output

power from the input power.

PD = PIN – POUT

= 14W – 13.2W ≈ 0.8W

With the power dissipation known, the temperature rise in the device may be estimated based on the theta JA

value (θJA). The θJA parameter estimates how much the temperature will rise in the device for every watt of

power dissipation. The EN6340QI has a θJA value of 12.5°C/W without airflow.

Determine the change in temperature (ΔT) based on PD and θJA.

ΔT = PD x θJA

ΔT ≈ 0.8W x 12.5°C/W ≈ 10°C

The junction temperature (TJ) of the device is approximately the ambient temperature (TA) plus the change in

temperature. We assume the initial ambient temperature to be 25°C.

TJ = TA + ΔT

TJ ≈ 25°C + 10°C ≈ 35°C

The maximum operating junction temperature (TJMAX) of the device is 125°C, so the device can operate at a

higher ambient temperature. The maximum ambient temperature (TAMAX) allowed can be calculated.

TAMAX = TJMAX – PD x θJA

≈ 125°C – 10°C ≈ 115°C

The maximum ambient temperature the device can reach is 115°C given the input and output conditions. Note

that the efficiency will be slightly lower at higher temperatures and this calculation is an estimate.

100

0.5

1.5

2.5

3.5

OUTPUT CURRENT (A)

Efficiency vs. Output Current

VOUT = 3.3V

CONDITIONS

VIN = 5.0V

13519

September 4, 2018

Rev D

EN6340QI Datasheet(PDF) 21 Page - Intel Corporation