PSC5A12-7iR Power-One AG, PSC5A12-7iR Datasheet - Page 5

• Manufacturer Part Number: PSC5A12-7iR
• Description: Positive Switching Regulators
• Manufacturer: Power-One AG

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I
Thermal Considerations
When a switching regulator is located in free, quasi-station-
ary air (convection cooling) at a temperature T
is operated at its nominal output current I
temperature T
phase, measured at the Measuring point of case tempera-
ture T
Under practical operating conditions, the ambient tempera-
ture T
(heat sink, fan, etc.) are taken to ensure that the case tem-
perature T
Example: Sufficient forced cooling allows T
simple check of the case temperature T
load ensures correct operation of the system.
Fig. 4
Output current derating versus temperature
Output Protection
A voltage suppressor diode which in worst case conditions
fails into a short circuit (or a thyristor crowbar, option C)
protects the output against an internally generated over-
voltage. Such an overvoltage could occur due to a failure of
either the control circuit or the switching transistor. The out-
put protection is not designed to withstand externally ap-
plied overvoltages. The user should ensure that systems
with Power-One power supplies, in the event of a failure, do
not result in an unsafe condition (fail-safe).
Fig. 3
Dynamic load regulation.
REV. MAY 12, 2004
V
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
o
1
0
o
/ I
0
I
o nom
o
T
/ I
A min
o nom
C
A
V od
(see: Mechanical Data ).
may exceed 71°C, provided additional measures
C
does not exceed its maximum value of 95°C.
50
Convection cooling
C
≥10 µs
will be about 95°C after the warm-up
t
d
60
70
Forced cooling
D V
o I
V od
80
C
90
≥10 µs
( T
C
t
A max
o nom
d
≤ 95°C) at full
A
100
= 71°C and
T
, the case
= 85°C. A
C max
T
D V
A
05010
[˚C]
Page 5 of 13
o I
t
t
Positive Switching Regulators (Industrial)
1.2
1.0
0.8
0.6
0.4
0.2
Fig. 5
Overload, short-circuit behaviour V
V
Parallel and Series Connection
Outputs of equal nominal voltages can be parallel-con-
nected. However, the use of a single unit with higher output
power, because of its power dissipation, is always a better
solution.
In parallel-connected operation, one or several outputs may
operate continuously at their current limit knee-point which
will cause an increase of the heat generation. Conse-
quently, the max. ambient temperature value should be re-
duced by 10 K.
Outputs can be series-connected with any other module. In
series-connection the maximum output current is limited by
the lowest current limitation. Electrically separated source
voltages are needed for each module!
Short Circuit Behaviour
A constant current limitation circuit holds the output current
almost constant whenever an overload or a short circuit is
applied to the regulator's output. It acts self-protecting and
recovers – in contrary to the fold back method – automati-
cally after removal of the overload or short circuit condition.
o
0
/ V
o nom
PSC Series Extended Data Sheet
0.2
0.4
0.6
0.8
1.0
o
versus I
I
o L
1.2
o
05033
.
1.4
I
o
/ I
o nom
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