Ericsson Internal
EJUNGYA
PRODUCT SPECIFICATION
4 (5)
Prepared (also subject responsible if other)
No.
3/1301-BMR 636 01/A4 Uen
11
Technical Specification
Approved
Checked
Date
Rev
Reference
EN/LZT 146 382 R1A June 2007
PKB 4717 PINB
DC/DC converters, Input 36-75 V, Output 10.5 A/75 W
SEC/D (Julia You)
ECHWANG 2007-6-18
A
© Ericsson Power Modules AB
Thermal Consideration continued
Connections
Definition of reference temperature (Tref
)
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 89.5 % = 0.895
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 (ΔT).
ΔT = 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 - ΔT.
E.g PKB 4717 PINB at 1m/s with full load:
1
1. ((
) - 1) × 75 W = 8.79 W
0.895
2. 8.79 W × 6.0°C/W = 53°C
3. 110 °C - 53°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.
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