psb246-2ir Power-One, psb246-2ir Datasheet - Page 4

• Manufacturer Part Number: psb246-2ir
• Description: Psb Series Extended Positive Switching Regulators Benign
• Manufacturer: Power-One

I
Fig. 3
Dynamic load regulation.
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 tem-
perature T
ures (heat sink, fan, etc.) are taken to ensure that the case
temperature T
80°C.
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.
V
o
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
REV. OCT 17, 2003
1
0
o
/ I
0
I
o nom
o
T
/ I
A min
o nom
C
V od
(see: Mechanical Data ).
Convection cooling
A
may exceed 50°C, provided additional meas-
40
C
C
does not exceed its maximum value of
will be about 80°C after the warm-up
10 µs
t
d
50
Forced cooling
D V
60
o I
V od
70
C
( T
10 µs
o nom
A max
C
80
t
A
d
80°C) at full
= 50 °C and
, the case
T
= 65°C. A
C max
T
A
D V
[ C]
Page 4 of 10
05010
o I
t
t
Output Protection
A voltage suppressor diode which in worst case conditions
fails into a short circuit, protects the output against an inter-
nally generated overvoltage. Such an overvoltage could
occur due to a failure of either the control circuit or the
switching transistor. The output protection is not designed
to withstand externally applied 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).
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.
Fig. 5
Overload, short-circuit behaviour V
1.2
1.0
0.8
0.6
0.4
0.2
Positive Switching Regulators (Benign)
V
o
0
/ V
o nom
PSB Series Extended Data Sheet
0.2
0.4
0.6
0.8
1.0
o
versus I
I
o L
1.2
o
05043
.
1.4
I
o
/ I
o nom