PKM4319EPI Ericsson Power Modules, PKM4319EPI Datasheet - Page 35

• Manufacturer Part Number: PKM4319EPI
• Description: Module DC-DC 1-OUT 2.5V 15A 37.5W 8-Pin Quarter-Brick
• Manufacturer: Ericsson Power Modules
• Type: Step Downr
• Series: PKM-Er

Specifications of PKM4319EPI

• Package: 8Quarter-Brick
• Output Current: 15 A
• Output Voltage: 2.5 V
• Input Voltage: 36 to 75 V
• Number Of Outputs: 1
• Output Power: 37.5 W
• Product: Isolated
• Input Voltage Range: 36 V to 75 V
• Output Voltage (channel 1): 1.5 V
• Output Current (channel 1): 20 A
• Isolation Voltage: 1.5 KV
• Package / Case Size: Quarter Brick
• Output Type: Isolated
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

General
Thermal Consideration
The PKM 4000E 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 4000E 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 . 6 .1W × 5 .5°C/W = 33 .6°C
C .110°C - 33 .6°C = max ambient temperature is 76 .4°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 4510E PI at 1m/s:
((1/η) - 1) × output power = power losses .
η = efficiency of converter . E .g 89% = 0 .89
T
PCB
0 .89
1
of DC/DC converter – temperature increase .
) - 1) × 49 .5W = 6 .1W
EN/LZT 146 051 R7A © Ericsson Power Modules, February 2007