PKB4313D datasheet(21/28 Pages) FLEX

21 / 28 page

Baseplate

Ambient Temperature Calculation

For products with base plate the maximum allowed ambient

temperature can be calculated by using the thermal resistance.

1. The power loss is calculated by using the formula

((1/η) - 1) × output power = power losses (Pd).

η = efficiency of product. E.g. 95.5% = 0.955

2. Find the thermal resistance (Rth) in the Thermal Resistance

graph found in the Output section for each model. Note that

the thermal resistance can be significantly reduced if a

heat sink is mounted on the top of the base plate.

Calculate the temperature increase (

∆T).

∆T = Rth x Pd

3. Max allowed ambient temperature is:

Max TP1 -

∆T.

E.g. PKB4313D at 1m/s:

1. ((

) -

1) × 300 W = 14.1 W

2. 14.1 W × 4.2°C/W = 59°C

3. 125 °C – 59°C = max ambient temperature is 66°C

The actual temperature will be dependent on several factors

such as the PWB size, number of layers and direction of

airflow.

Connections

Designation

Function

+In

Positive Input

Remote Control

-In

Negative Input

-Out

Negative Output

+Out

Positive Output

0.955

PKB4000D series Fully regulated DC-DC Converters

Input 36-75 V, Output up to 25 A / 300 W

28701-BMR674 01 Rev G

July 2019

Technical Speciﬁcation

PKB4313D データシート(PDF) 21 Page - Flex Power Modules. FLEX LTD.

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