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Benign Environment
Switching Regulators, PCB + Chassis
FD-Family
Edition 2/96 - Melcher AG
4 - 85
MELCHER
The Power Partners.
4.3
Description
The FD-Family features very compact designed switching
regulators in a miniature size case for surface mount,
hence, these converters have an extremely high power
density. With a high efficiency of up to 87 %, very stable out-
put voltages as well as high reliability, the FD-family be-
comes a perfect choice for the supply of LCD's, non-volatile
memories, voltage distribution in 5 V logical circuits and
CCD applications. Furthermore, a special master-slave
connection allows safe parallel operation of two or more
units. For a wide variety of filtering circuits for smooth out-
put voltages, a full range of optional choke coils are avail-
able.
Remarks:
Smoothing capacitors should be connected within 15 mm
from the converter pins.
It is recommended to use low impedance smoothing ca-
pacitors with high frequency rating. Refer to the table above
for recommended external capacitors.
Filtering Recommendations
Circuit design by means of adding input and output capaci-
tors in order to reduce ripple and noise to a moderate value.
C1
C2
Vi
SD
GND
Vo–
GND
Vo+
1
6
PDR
Fig. 1
External circuitry for 2 output units
Fig. 2
External circuitry for 1 output step down units
C1
C2
Vi
SD
GND
n.c.
GND
Vo+
1
6
PDR
Table 2b: Recommended external capacitors
Table 2a: Recommended external capacitors
Safety and Installation Instructions
Safety for Step Down Types
If the output circuit of a switching regulator is operator-ac-
cessible according to the IEC 950 related safety standards,
it shall be an SELV circuit (Safety Extra Low Voltage circuit,
i.e. a circuit, separated from mains by at least basic insula-
tion, that is so designed and protected that under normal
and single fault conditions, the voltage between any two
conductors and between any conductor and earth does not
exceed DC 60 V).
In the following statement an interpretation is provided of
the IEC 950 safety standard with respect to the safety sta-
tus of the output circuit. However, it is the sole responsibility
of the installer or user to assure the compliance with the
relevant and applicable safety standards:
If the input circuit of a switching regulator is an SELV circuit,
it’s output is considered to be an SELV circuit.
Safety for Step Up Types
If the output circuit of a switching regulator is operator-ac-
cessible according to the IEC 950 related safety standards,
it shall be an SELV circuit (Safety Extra Low Voltage circuit,
i.e. a circuit, separated from mains by at least basic insula-
tion, that is so designed and protected that under normal
and single fault conditions, the voltage between any two
conductors and between any conductor and earth does not
exceed DC 60 V).
In the following statement an interpretation is provided of
the IEC 950 safety standard with respect to the safety sta-
tus of the output circuit. However, it is the sole responsibility
of the installer or user to assure the compliance with the
relevant and applicable safety standards:
If the input circuit of a switching regulator is an SELV circuit
and the output is protected against overvoltages higher
than 60 V by external means, e.g. an overvoltage suppres-
sor diode, the output is considered to be an SELV circuit.
C1
Ii ripple
Type
Io ripple
C2
(mArms)
OS-CON
535
FDD 1106
100
SP Cap
10
F/20 V
490
FDD 1206
105
22
F/8 V
in parallel
575
FDD 1203
135
Al-Chip
450
FDB 1001
245
same as
C1
33
F/25 V
FDB 1002
215
425
FDB 2001
125
OS CON
415
FDB 2002
105
3.3
F/20 V
in parallel
Al-Chip
33
F/25 V
C1
Ii ripple
Type
Io ripple
C2
(mArms)
OS-CON
245
FDF 1301
205
same as
C1
3.3
F/20 V
240
FDF 1302
180
in parallel
260
FDF 2301
135
Al-Chip
250
FDF 2302
130
33
F/25 V
475
FDF 1103
395
SP Cap
OS-CON
22
F/8 V
10
F/20 V
in parallel
Al-Chip
33
F/25 V
33
F/25 V
295
FDF 1105
55
Al-Chip
270
FDF 1205
60
10
F/50 V
2 in parallel