MIC2132 datasheet(37/48 Pages) MICROCHIP

37 / 48 page

 2022 Microchip Technology Inc. and its subsidiaries

DS20006654B-page 37

MIC2132

The maximum recommended operating junction

temperature for the MIC2132 is +125°C. Using the out-

put voltage of the same switching converter when it is

between 4.7V (typical) and 14V, as the voltage at the

EXTVDD pin, significantly reduces the power dissipa-

tion inside the MIC2132. This reduces the junction

temperature rise as further illustrated.

For a typical case of VIN = 36V, VOUT = 5V, IG(TOTAL) =

20 mA, IQ = 5 mA and a maximum ambient temperature

of TA = +85°C when the EXTVDD is not used, the

MIC2132 junction temperature is calculated as shown

in Equation 5-43.

EQUATION 5-43:

When the EXTVDD is used and the 5V output of the

MIC2132 buck converter is used as the input to the

EXTVDD pin, the MIC2132 junction temperature is

calculated as shown in Equation 5-44. The junction

temperature is reduced significantly, from +115.6°C to

+89.3°C when the EXTVDD is used.

EQUATION 5-44:

5.9

Thermal Measurements

It is a good idea to measure the IC’s case temperature

to make sure it is within its operating limits. Although

this might seem an elementary task, it is easy to get

false results. The most common mistake is to use the

standard thermal couple that comes with a thermal

meter. This thermal couple wire gauge is large, typically

22 gauge, and behaves like a heatsink, which results in

a lower case temperature measurement.

There are two methods of temperature measurement:

using a smaller thermal couple wire or using an infrared

thermometer. If a thermal couple wire is used, it must

be constructed of 36 gauge wire or higher (smaller wire

size) to minimize the wire heatsinking effect. In addi-

tion, the thermal couple tip must be covered in either

thermal grease or thermal glue to ensure that the

thermal couple junction makes good contact with the

case of the IC. Wherever possible, an infrared

thermometer is recommended. The measurement spot

size of most infrared thermometers is too large for an

accurate reading on a small form factor IC. However,

an IR thermometer with a 1 mm spot size is a good

choice for measuring the hottest point on the case. An

optional stand can be used to make it easy to hold the

beam on the IC for long periods of time. In addition, a

more advanced, convenient and accurate infrared

thermal camera can be used, although such equipment

is much more expensive.

PIC = 36V × (20 mA + 5 mA)

PIC = 0.9W

TJ = 0.9W × 34ºC/W + 85ºC

TJ = 115.6ºC

PIC = 5V × (20 mA + 5 mA)

PIC = 0.125W

TJ = 0.125W × 34ºC/W + 85ºC

TJ = 89.3ºC

MIC2132 Datasheet(PDF) 37 Page - Microchip Technology

MIC2132 Datasheet(HTML) 37 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Datasheet Download

Link URL