DTO25 datasheet(3/6 Pages) VISHAY

3 / 6 page

DTO25

www.vishay.com

Vishay Sfernice

Revision: 23-Sep-15

Document Number: 51054

For technical questions, contact: sferfixedresistors@vishay.com

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000

POWER RATING

The temperature of the case should be maintained within the limits specified.

CHOICE OF THE BOARD

The user must choose the board according to the working conditions of the component (power, room temperature). Maximum

working temperature must not exceed 150 °C. The dissipated power is simply calculated by the following ratio:

Expressed in W

ΔT:

Difference between maximum working temperature and room temperature

RTH (j - c): Thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal resistance

of the component: 5 °C/W.

RTH (c - h): Thermal resistance value measured between outer side of the resistor and upper side of the board. This is the thermal

resistance of the solder layer.

RTH (h - a): Thermal resistance of the board.

Example:

RTH (c - h) + RTH (h - a) for DTO25 power rating 3 W at ambient temperature +25 °C.

Thermal resistance RTH (j - c): 5 °C/W

Considering equation (1) we have:

ΔT = 150 °C - 25 °C = 125 °C

RTH (j - c) + RTH (c - h) + RTH (h - a) =

ΔT/P = 125/3 = 41.7 °C/W

RTH (c - h) + RTH (h - a) = 41.7 °C/W - 5 °C/W = 36.7 °C/W

ACCIDENTAL OVERLOAD

In any case the applied voltage must be lower than the maximum overload voltage of Us = 300 V. The values indicated on the

graph below are applicable to resistors onto a board.

ENERGY CURVE at 25 °C

POWER CURVE at 25 °C

100

CASE TEMPERATURE IN °C

100

150

200

ΔT

TH (j - c)

TH (c - h)

TH (h - a)

-------------------------------------------------------------------------------------------

()

0.001

0.01

0.1

100

OVERLOAD DURATION IN s

-7

-6

-5

-4

-3

-2

-1

OVERLOAD DURATION IN s

-7

-6

-5

-4

-3

-2

-1

1000

10 000

100 000

100

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