
T Series Data Sheet
?
500 Watt AC-DC Converters
Input Fuse
An input fuse (5 × 20 mm) in series with the input line (L)
inside the converter protects against severe defects; see also
Safety and Installation Instructions. For applications with
accessible fuse, see Option F .
Table 3: Fuse Type
mA/W
3.5
3.0
2.5
04026a
Series
LT
UT
Schurter type
SPF 6.3 A, 250 V
SPT 10 A, 250 V
Part number
0001.1012
0001.2514
2.0
1.5
1.0
Limit class D according
to IEC/EN 61000-3-2
Inrush Current
0.5
The converters exhibit an input capacitance of only 4 μF,
resulting in a low and short peak current, when the converter
0
3
5
7
9
11
13
15
17
Harm.
is connected to the mains. During switch-on, the converter
current can rise up to the input current limit I i L .
As a direct result of the low and short inrush current and
controlled charging procedure of the output capacitors, the
converter can be hot swapped. The LT inrush current is a
Fig. 3
Harmonic distortion at input LT1740-7Z, V i = V inom , I o = I o nom
factor 10 smaller than defined in the ETS 300132-1 standard
for Telecom systems. However the converter should be
plugged-in smoothly, giving time to the output capacitors to be
charged.
Input Under- /Overvoltage Lockout
If the specified input voltage range V i is exceeded, the
converter stops operation temporarily resulting in reduced
output power and increased RFI. The input is protected by
varistors. Continuous overvoltage will destroy the converter.
If the sinusoidal input voltage stays below the input under-
mA/W
3.5
3.0
2.5
2.0
1.5
1.0
0.5
Limit class D according
to IEC/EN 61000-3-2
04025a
voltage lockout threshold V i , the converter will be inhibited.
Power Factor, Harmonics
0
3
5
7
9
11
13
15
17
Harm.
Power factor correction PFC is achieved by controlling the
input current waveform synchronously with the input voltage.
PF
Fig. 4
Harmonic distortion at input UT1740-7Z, V i = V inom , I o = I o nom
1.00
0.98
04023a
0.96
0.94
04024a
0.96
0.94
0.92
0.90
0.88
0.86
0.84
0.82
0.92
0.90
0.88
0.86
0.84
0.82
0
2 4 6 8 10
12
14
16
I o [A]
0
2 4 6
8
10 12 14
16
I o [A]
UT1740-7Z at V i = 110 VAC
LT1740-7Z at V i = 230 VAC
Fig. 2
Power factor
BCD20023 Rev AB, 02-Nov-2010
V i = 110 VAC
Fig. 5
Efficiency versus load of LT1701
Page 5 of 31
U i = 230 VAC
www.power-one.com