LTO30 datasheet(2/4 Pages) VISHAY

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LTO 30

Vishay Sfernice

Document Number: 50049

Revision 30-May-06

TESTS

CONDITIONS

TYPICAL DRIFTS

Momentary Overload

EN 60115-1

± (0.5 % + 0.005

Ω)

1.5 Pr/5 s

Us < 1.5 UL

EN 60115-1

Rapid Temperature Change

IERC 60068-2-14 Tests Na

5 cycles

± (0.5 % + 0.005

Ω)

- 55 °C to + 155 °C

Load Life

EN 60115-1

± (1 % + 0.005

Ω)

1000 h Pr at + 25 °C

Humidity (Steady State)

MIL STD 202

± (0.5 % + 0.005

Ω)

Method 103 B Cond. D

Vibration

MIL STD 202

± (0.2 % + 0.005

Ω)

Method 204 Cond. D

Terminal Strength

MIL STD 202

± (0.2 % + 0.005

Ω)

Method 211 Cond. A1

Shock

100G, MIL STD 202

± (0.5 % + 0.005

Ω)

Method 213 Cond. I

PERFORMANCE

30 Watt Power Resistor Thick Film Technology

Resistance Values

≥ 0.010

≥ 0.015

≥ 0.1

≥ 0.5

Tolerances

± 1 % at ± 10 %

± 900 ppm/°C

± 700 ppm/°C

± 250 ppm/°C

± 150 ppm/°C

SPECIAL FEATURES

Typical Temperature

Coefﬁcient

(- 55 °C/+ 155 °C)

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.

RTH: (c-a): thermal resistance value measured between outer side of the resistor and room temperature. It is the

thermal resistance of the heatsink itself (type, shape), the quality of the fastening device, and the thermal resistance of the

thermal compound.

Example:

RTH: (c-a) for LTO30 power rating 10 W at ambient temperature + 30 °C.

Thermal resistance RTH (j-c): 4.2 °C/W

Considering equation (1) we have:

ΔT = 155 °C - 30 °C = 125 °C

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

= 12.5 °C/W

RTH (c-a) = 12.5 °C/W - 4.2 °C/W = 8.3 °C/W

with a thermal grease RTH (c - h) = 1 °C/W, we need a heat sink with RTH (h - a) = 7.3 °C/W

CHOICE OF THE HEATSINK

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

Maximum working temperature must not exceed 155 °C. The dissipated power is simply calculated by the following ratio:

P =

ΔT

[RTH (j-c) + RTH (c-a)]

ΔT

125

(1)

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