PSR Series
Switching Regulators, PCB & Chassis
Industrial Environment
Edition 4/4.99
2/11
MELCHER
The Power Partners.
Type Key
PSR 12 2.5 -7 i R P Y
Positive switching regulator in case A01 ..................... PSR
Nominal output voltage in volt ................................... 5...36
Nominal output current in ampere ............................... 2...5
Operational ambient temperature range
T
A
–25...71
°C ........................................................... -7
–40...71
°C (option) .............................................. -9
Options:
Inhibit input ............................................................ i
Control input for output voltage adjustment 1 ....... R
Potentiometer 1 ..................................................... P
PCB soldering pins 0.5
× 1.0 mm ......................... Y
1 Option R excludes option P and vice versa.
Example:
PSR 122.5-7iPY = A positive switching regulator with a 12 V, 2.5 A output, ambient temperature range of
–25…71
°C, inhibit input, potentiometer and PCB soldering pins.
Control circuit
Go–
Vo+
Gi–
Vi+
Input
Filter
R (option)
i (option)
Io
U o
Ii
U i
03015
Ce
Option P
Fig. 1
Block diagram
Functional Description
The switching regulators are designed using the buck con-
verter topology. See also:
Technical Information: Topolo-
gies. The input is not electrically isolated from the output.
During the on period of the switching transistor, current is
transferred to the output and energy is stored in the output
choke in the form of flux. During the off period, this energy
forces the current to continue flowing through the output,
to the load and back through the freewheeling diode.
Regulation is accomplished by varying the on to off duty
ratio of the power switch.
These regulators are ideal for a wide range of applica-
tions, where input to output isolation is not necessary, or
where already provided by an external front end (e.g. a
transformer with rectifier). To optimise customer’s needs,
additional options and accessories are available.