CHB75 Datasheet, PDF (2/5 Pages) RSG Electronic Components GmbH – 37.5 TO 75 WATT WIDE INPUT DC-DC CONVERTERS SINGLE & DUAL OUTPUT

Application Note
Derating
The operating case temperature range of the CHB75 series is -40˚C to +100˚C. When operating the CHB75 , proper derating
or cooling is needed .
Following is the derating curve of CHB75 without heat sink
Power Dissipated vs Ambient Temperature and Air Flow
25
20
15
10
5
0
0
10
20
30
40
50
60 70
80
90
100
Ambient Temperature, Ta(Deg. C)
Forced Convection Power Derating with No Heat Sink
Natural Convection
20 ft./min. (0.1 m/s)
100 ft./min. (0.5 m/s)
200 ft./min. (1.0 m/s)
300 ft./min. (1.5 m/s)
400 ft./min. (2.0 m/s)
Where:
The power dissipation (Pd):
Pd = Pi - Po = Po (1- ) /
The thermal resistance are list below:
Chart of Thermal Resistance vs Air Flow:
AIR FLOW RATE
Natural Convection
100 ft./min.
200 ft./min.
300 ft./min.
400 ft./min.
TYPICAL Rca
7.12 ˚C/W
6.21 ˚C/W
5.17 ˚C/W
4.29 ˚C/W
3.64 ˚C/W
The temperature rise ( T ):
T = Pd * Rca
75
Remote ON/OFF Control
The CHB75 series allows the user to switch the module on and off electronically with remote on/off feature. The CHB75 series
are available with "positive logic" or "negative logic" (option).
HIGH SIGNAL HERE
DISABLE OUTPUT
ON/OFF (2)
-VIN (4)
Logic State
(PIN 2)
Logic Low -
Switch Closed
Logic Table
Negative Logic
Module on
Positive Logic
Module off
Logic High -
Switch Open
Module off
Module on
External Output Trimming
Output may optionally be externally trimmed
(±10%) with a fixed resistor or an external trim-
pot as shown.
+SENSE (8)
TRIM DOWN
TRIM (7)
TRIM UP
-SENSE (6)
+SENSE (8)
TRIM (7)
-SENSE (6)
10K ohms
TRIMPOT
Output Noise
The output noise is measured with 10µF tantalum capacitor and 1.0µF ceramic capacitor across output.
+Vout (9)
Ceramic
1.0µF
Resistor
Load
-Vout (5)
Solid tantalum
10µF
To
Scope
Output Noise Test Circuit schematic
76
All Specifications Typical At Nominal Line, Full Load and 25˚C Unless Otherwise Noted.