Ericsson Internal
EJUNGYA
PRODUCT SPECIFICATION
4 (5)
Prepared (also subject responsible if other)
No.
3/1301-BMR 636 Uen
41
Technical Specification
Approved
Checked
Date
Rev
EN/LZT 146 3R9e4feRre5nDce October 2013
PKB 4000 series
SEC/D (Julia You)
ESHUHAN
2008-1-11
A
© Ericsson AB
DC/DC converters, Input 36-75 V, Output 30 A/90 W
Thermal Consideration continued
Definition of reference temperature (Tref
Connections
)
The reference temperature is used to monitor the temperature
limits of the product. Temperatures above maximum Tref are
not allowed and may cause degradation or permanent
damage to the product. Tref is also used to define the
temperature range for normal operating conditions.
Tref 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 89.0 % = 0.89
Pin
Designation
+In
Function
Positive input
1
2
3
4
5
6
7
8
RC
Remote control
2. Find the thermal resistance (Rth) in the Thermal Resistance
graph found in the Output section for each model.
Calculate the temperature increase (∆T).
∆T = Rth x Pd
-In
Negative input
-Out
-Sen
Vadj
+Sen
+Out
Negative output
Negative remote sense
Output voltage adjust
Positive remote sense
Positive output
3. Max allowed ambient temperature is:
Max Tref - ∆T.
E.g PKB 4711 SINB at 1m/s:
1
1. ((
) - 1) × 75 W = 9.26 W
0.89
2. 9.26 W × 6.3°C/W = 58.3°C
3. 120 °C — 58.3°C = max ambient temperature is 61.6°C
The actual temperature will be dependent on several factors
such as the PCB size, number of layers and direction of
airflow.
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