HBR Series of Railway Half-Brick
[Type text]
[Type text]
[Type text]
Up to 150 Watts DC-DC Converter
Power De-rating
The operating case temperature range of HBR series is -40°C to +100°C. When operating the HBR series, proper de-rating or cooling is needed.
The maximum case temperature under any operating condition should not exceed + 100°C.
The following curve is the de-rating curve of HBR series without heat sink.
AIR FLOW RATE
TYPICAL Rca
Natural Convection
20ft./min. (0.1m/s)
7.12 ℃/W
100 ft./min. (0.5m/s)
200 ft./min. (1.0m/s)
300 ft./min. (1.5m/s)
400 ft./min. (2.0m/s)
500 ft./min. (2.5m/s)
600 ft./min. (2.5m/s)
700 ft./min. (2.5m/s)
800 ft./min. (2.5m/s)
6.21 ℃/W
5.17 ℃/W
4.29 ℃/W
3.64 ℃/W
2.96 ℃/W
2.53 ℃/W
2.37 ℃/W
2.19 ℃/W
Example (without heat sink):
What is the minimum airflow necessary for a HBR113S12-12.5 operating at nominal line voltage, an output current of 12.5A, and a maximum
ambient temperature of 40°C?
Solution:
Given: Vin=110Vdc, Vo=12Vdc, Io=12.5A
Determine Power dissipation (Pd):
Pd =Pi-Po=Po(1-η)/η
Pd =12V×12.5A×(1-0.925)/0.925=12.16Watts
Determine airflow:
Given: Pd =12.16W and Ta=40°C
Check Power Derating curve:
Minimum airflow= 300 ft./min.
Verify:
Maximum temperature rise is
ΔT = Pd × Rca=12.16W×4.29=52.17°C.
Maximum case temperature is
Tc=Ta+ΔT=92.17°C <100°C.
Where:
The Rca is thermal resistance from case to ambient environment.
Ta is ambient temperature and Tc is case temperature.
September 16 -2017 A.04
Page 6 of 15
DATEL [ DATEL, Inc. ]
