Rugged Environment
DC-DC Converters >100 W
K-Family
Edition 2/96 - Melcher AG
8 - 25
MELCHER
The Power Partners.
8.1
3
5.1 V
4.875 V
0
U
i [V DC]
0
t
U
ti + Uhi
U
ti
Input voltage failure
Switch-on cycle
Input voltage sag
Switch-on cycle and subsequent
input voltage failure
U
V high
U
V low
U
V
0
V2
t
U
o1
0
U
V high
U
V low
U
V
0
V2
U
i
U
ti
4
Output voltage failure
0
U
V high
U
V low
U
V
3
U
ti hi
t
low min
2
t
low min
2
t
low min
2
3
4
U
V high
U
V low
U
V
0
V3
t
3
t
low min
2
t
low min
2
3
t
h
1
2.0 V
t
h
1
4
3
4
t
low min
2
V3
5.1 V
4.875 V
0
U
o1
2.0 V
Input voltage monitoring
Output voltage monitoring
Threshold tolerances and hysteresis:
If
Ui is monitored, the internal input voltage is measured af-
ter the input filter and rectifier (LK types). Consequently this
voltage differs from the voltage at the connector pins by the
voltage drop
Uti across input filter and rectifier. The
threshold level of option V0 is adjusted during manufacture
at
Io nom and TA = 25 °C. The value of U ti depends upon the
input voltage range (AK, BK, ...), threshold level
U t, tem-
perature and input current. The input current is a function of
input voltage and output power.
Option B1 Cooling Plate (see "Mechanical Data")
Where a cooling surface is available, we recommend the
use of a cooling plate (option B1) instead of the standard
heatsink. The mounting system should ensure sufficient
cooling capacity to guarantee that the maximum case tem-
Fig. 30
Relationship between Ui, Uo1, U V, IV and Uo1/Uo nom ver-
sus time.
1 VME request: minimum 4 ms
2 t low min = 40...200 ms, typically 80 ms
3 UV level not defined at Uo1 < 2.0 V
4 The V signal drops simultaneously with the output voltage. If the
pull-up resistor
RP is connected to Vo1+. The V signal remains
high if
RP is connected to an external source.
U
ti
U
hi
U
V low
U
V
U
V high
U
i
P
o
=
P
o
nom
P
o
=
0
P
o
=
0
U
ti
P
o
=
P
o
nom
perature
TC max is not exceeded. The cooling capacity is cal-
culated by:
(100% –
η)
PLoss = –––––––––– (Uo Io)
η
Efficiency
η see Type survey
Fig. 29
Definition of Uti,
Uti and Uhi