PKB4113CPI datasheet(36/43 Pages) ERICSSON

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Ericsson Internal

PRODUCT SPECIFICATION

4 (6)

Prepared (also subject responsible if other)

No.

ESHUHAN

3/1301-BMR 655 Uen

Approved

Checked

Date

Rev

Reference

SEC/D (Betty Wu)

EZHEWNG

2009-2-13

Thermal Consideration

General

The converters are designed to operate in different thermal

environments and sufficient cooling must be provided to

ensure reliable operation.

Cooling is achieved mainly by conduction, from the pins to the

host board, and convection, which is dependant on the airflow

across the converter. Increased airflow enhances the cooling

of the converter.

The Output Current Derating graph found in the Output section

for each model provides the available output current vs.

ambient air temperature and air velocity at Vin = 53 V.

The DC/DC converter is tested on a 254 x 254 mm,

35 µm (1 oz), 8-layer test board mounted vertically in a wind

tunnel with a cross-section of 305 x 305 mm.

Proper cooling of the DC/DC converter can be verified by

measuring the temperature at positions P1 or P2 ( see note 1).

The temperature at these positions should not exceed the max

values provided in the table below.

See Design Note 019 for further information.

Position

Device

Designation

max value

Mosfet

Tp1

125º C

Ind. core

Tp2

125º C

Thermal Consideration continued

The PKB4000C series DC/DC converters can be ordered with

a heatsink (HS) option. The HS option is intended to be

mounted on a cold wall or heatsink to transfer heat away from

the converter and further improve the cooling of the converter.

Definition of reference temperature (Tp1)

The reference temperature is used to monitor the temperature

limits of the product. Temperatures above maximum Tp1 are

not allowed and may cause degradation or permanent damage

to the product. Tp1 is also used to define the temperature

range for normal operating conditions.

Tp1 is defined by the design and used to guarantee safety

margins, proper operation and high reliability of the module.

Ambient Temperature Calculation

By using the thermal resistance the maximum allowed ambient

temperature can be calculated.

1. The power loss is calculated by using the formula

((1/

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

η = efficiency of converter. E.g. 89.5 % = 0.895

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

graph found in the Output section for each model.

Calculate the temperature increase (

ΔT).

ΔT = Rth x Pd

3. Max allowed ambient temperature is:

Max Tp1 -

ΔT.

E.g. PKB 4110C PI at 1m/s:

1. ((

) -

1) × 132 W = 14.7 W

2. 14.7 W × 4.6°C/W = 68°C

3. 125 °C – 68°C = max ambient temperature is 57°C

The actual temperature will be dependent on several factors

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

airflow.

Note 1

P2 is the limiting component (Tp1) used for thermal derating for

PKB4113C. P1 is used for the rest of the modules in the PKB-C family.

0.90

PKB4000C series Direct Converters

Input 36-75 V, Output up to 60 A / 144 W

EN/LZT 146 377 R4

D September 2013

Technical Speciﬁcation

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