Datasheet
DC/DC Converter
RPP-3
REV.: 3/2016www.recom-power.com
ENVIRONMENTAL
Parameter Condition
Value
Relative Humidity 95%, non condensing
Temperature Coefficient ±0.04% / °C max.
Thermal Impedance
natural convection, mounting at FR4
(254x254mm) PCB
vertical
horizontal
7.2°C/W
7.8°C/W
Operating Temperature Range start up at -45°C -45°C to (see calculation)
Maximum Case Temperature +115°C
MTBF
according to MIL-HDBK-217F (+50°C G.B.)
according to BellCore-TR-332 (+50°C G.B.)
768 x 10
3
hours
1572 x 10
3
hours
continued on next page
Derating Graph
(Ta= +25°C, natural convection, typ. Vin and vertical mounting)
Calculation
Specifications (measured @ ta= 25°C, nominal input voltage, full load and after warm-up)
RPP20-2405SW
Series
0
30
25
35
40
45
50
10 20 30 40 50 60 70 80 90 100
Load [%]
Case Temperature [°C]
9
50
60
70
80
90
100
12 15 18 21 24 27 30 33 36
Input Voltage [V]
Efficiency [%]
10
50
60
70
80
90
100
20 30 40 50 60 70 80 90 100
36Vin
9Vin
24Vin
Load [%]
Efficiency [%]
R
thcase-ambient
= 7.2°C/W (vertical) T
case
= Case Temperature
R
thcase-ambient
= 7.8°C/W (horizontal) T
ambient
= Environment Temperature
P
dissipation
= Internal losses
R
thcase-ambient
=
T
case
- T
ambient
P
IN
= Input Power
P
dissipation
P
OUT
= Output Power
h = Efficiency under given Operating Conditions
P
dissipation
= P
IN
- P
OUT
=
P
OUTapp
- P
OUTapp
R
thcase-ambient
= Thermal Impedance
h
Practical Example:
Take the RPP20-2405SW with 50% load. What is the maximum ambient operating temperature? Use converter vertical in application.
Eff
min
= 88% @ V
nom
P
OUT
= 20W
P
OUTapp
= 20 x 0.5 = 10W
P
dissipation
=
P
OUTapp
- P
OUTapp
R
th
=
T
casemax
- T
ambient
--> 7.2°C/W =
115°C -
T
ambient
h
P
dissipation
1.49W
h = ~87% (from Eff vs Load Graph)
T
ambientmax
= 104.3°C
P
dissipation
=
10
- 10 = 1.49W
0.87