PKM2515EPI Ericsson Power Modules, PKM2515EPI Datasheet - Page 23

• Manufacturer Part Number: PKM2515EPI
• Description: DC/DC Converters & Regulators 15Vdc 3.3A Isolated Input 18-36V 50W
• Manufacturer: Ericsson Power Modules
• Series: PKM-Er

Specifications of PKM2515EPI

• Output Power: 50 W
• Input Voltage Range: 18 V to 36 V
• Number Of Outputs: 1
• Output Voltage (channel 1): 15 V
• Output Current (channel 1): 3.3 A
• Package / Case Size: Quarter Brick
• Output Type: Isolated
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

General
Thermal Consideration
The PKM 2000E Series DC/DC converters are designed
to operate in a variety of thermal environments, however
sufficient cooling should be provided to help ensure reliable
operation . Heat is removed by conduction, convection and
radiation to the surrounding environment . Increased airflow
enhances the heat transfer via convection . The available load
current vs . ambient air temperature and airflow at Vin=53 V
for each model is according to the information given under
the output section . The test is done in a wind tunnel with a
cross section of 305x305mm, the DC/DC converter vertically
mounted on a 8 layer PCB with a size of 254x254mm .
Proper cooling can be verified by measuring the temperature
of selected devices . Peak temperature can occur at position
P1 and P2 . The temperature at these positions should not
exceed the recommended max values .
PKM 2000E PI Datasheet
Position
P1
P2
Transformer
Mosfet
Device
T
T
core
surface
T
critical
Max Value
110ºC
110ºC

Calculation of ambient temperature
By using the thermal resistance the maximum allowed
ambient temperature can be calculated .
1 . The powerloss is calculated by using the formula
2 . Find the value of the thermal resistance for each product in
the diagram by using the airflow speed at the output section
of the converter . Take the thermal resistance x powerloss to
get the temperature increase .
A . ((
B . 7 .4W × 6°C/W = 44 .4°C
C .110°C - 44 .4°C = max ambient temperature is 65 .6°C
The real temperature will be dependent on several factors,
like PCB size and type, direction of airflow, air turbulence
etc . It is recommended to verify the temperature by testing .
3 . Max allowed calculated ambient temperature is: Max
E .g PKM 2510E PI at 1m/s:
((1/η) - 1) × output power = power losses .
η = efficiency of converter . E .g 89% = 0 .89
T
PCB
0 .87
1
of DC/DC converter – temperature increase .
) - 1) × 49 .5W = 7 .4W
EN/LZT 146 050 R4A © Ericsson Power Modules, March 2007