Auxiliary Functions
Shut Down Function
The outputs of the converters may be enabled or disabled
by means of a logic signal (TTL, CMOS, etc.) applied to the
shut down pin. If the shut down function is not required then
pin should be left open-circuit.
Converter operating:
Converter shut down:
2.0...5.0 V
–1...0.7 V
Fig. 9
Output voltage Trim.
Table 7: U
o
versus U
ext
for U
o
= 90...110% U
o nom
;
typical values (U
i nom
, I
o1/2
= 0.5 I
o1/2 nom
)
R
ext 1
U
o nom
[V]
3.3
R
ext 2
[k]
8
U
o
[V]
2.97
U
o
[V]
3.63
[k]
5
The shut down pin can also be used as a programmable
undervoltage lockout. The undervoltage lockout values for
the 48 IMS30 series is 31 V with a 0.5V hysteresis window
which can be trimmed up by means of an external resistor
connected between the SD/PUL pin and Vi– pin.
06133
Thermal Considerations
If a converter, mounted on a PCB, is located in free, quasi-
stationary air (convection cooling) at the indicated maxi-
mum ambient temperature
T
A max
(see table:
Temperature
specifications)
and is operated at its nominal input voltage
and output power, the case temperature
T
C
measured at the
Measuring point of case temperature T
C
(see:
Mechanical
Data)
will approach the indicated value
T
C max
after the
warm-up phase. However, the relationship between
T
A
and
T
C
depends heavily on the conditions of operation and inte-
gration into a system. The thermal conditions are influenced
by input voltage, output current, airflow, temperature of sur-
rounding components and surfaces and the properties of
the printed circuit board.
T
A max
is therefore only an indica-
tive value and under practical operating conditions, the ad-
missible ambient temperature
T
A
may be higher or lower
than this value.
Caution:
The case temperature
T
C
measured at the
Measuring point of case temperature T
C
(see:
Mechani-
cal Data)
must under no circumstances exceed the
specified maximum value. The installer must ensure that
under all operating conditions
T
C
remains within the lim-
its stated in the table:
Temperature specifications.
Short Circuit Behaviour
The current limit characteristic shuts down the converter
whenever a short circuit or an overload is applied to its out-
put. It acts self-protecting and automatically recovers after
removal of the overload condition (hiccup mode).
Overtemperature Protection
The converters are protected from possible overheating by
means of an internal non latching temperature monitoring
circuit. It shuts down the unit above the internal tempera-
ture limit and attempts to automatically restart in short peri-
ods. This feature prevents excessive internal temperature
excursion which could occur in heavy overload conditions.
Extendable output power characterisation of 48IMS30-0302-9G
under forced air condition
32
30
Vi+
SD/PUL
Vo+
R
ext
Vi–
Vo–
Fig. 8
Shut down (SD) and undervoltage lockout (PUL) function.
Table 6: Typical values for undervoltage lockout (PUL)
settings.
48 IMS 30
R
ext
[k ]
50
29
20
15
U
i min
[V]
31
34
36
38
40
Synchronisation
The IMS 30 provides a bi-directional synchronisation func-
tion to synchronise several IMS 30 units operated in parallel
connection. When the W pins (SYNC) are connected to-
gether, the converters will lock to the highest switching fre-
quency. The faster controller becomes the master, produc-
ing a 4.3 V, 200 ns pulse train. Only one, the highest fre-
quency SYNC signal, will appear on the Sync line.
Adjustable Output Voltage
As a standard feature, the IMS 30 units offer adjustable
output voltage by using the secondary referenced control
Trim. If the control input is left open-circuit the output volt-
age is set to
U
o nom
. Adjustment of the output voltage is pos-
sible by means of an external resistor
R
ext
connected be-
tween the Trim pin and the either Vo+ or Vo–.
06134
Output Power (W)
28
26
24
22
Vi+
Vo+
R
ext 1
Trim
R
ext 2
Vi–
Vo–
20
0
100
200
300
400
500
600
700
800
Air-Flow (LFM)
6/11
POWER-ONE [ POWER-ONE ]
