LL1545A , page 1
Audio Transformer
LL1545A
LL1545A is a general-purpose audio transformer with a variety of connection alternatives. The transformer is
built up from two coils, each with a secondary winding surrounded by shields and two primary windings. This
structure results in an excellent frequency response. The transformer can be used in many different applications
such as a high impedance line input transformer (accepting signal levels of 22 dBU @ 40 Hz with primaries in
series), for splitting or as a microphone input transformer.
The LL1545A is made with a mu-metal core and is housed in a mu-metal can.
Refer to page 2 of this sheet for termination alternatives.
Turns ratio:
1 + 1 + 1 + 1 : 2 + 2
Dims: (Length x Width x Height above PCB (mm))
37 x 22.5 x 14.5
Pin Layout (viewed from component side) and Windings Schematics:
Spacing between pins:
2.54 mm (0.1")
Spacing between rows of pins:
22.86 mm (0.9")
Weight:
46 g
Rec. PCB hole diameter:
1.5 mm
Static resistance of each primary (average):
147
Ω
Static resistance of each secondary (average):
295
Ω
Self resonance point:
> 220 kHz
Recommended load for best square-wave response
(Termination alternative A below):
6.7 k
Ω + 470 pF
Frequency response
(source 600
Ω , load (6.7 kΩ + 470 pF) in parallel with 56 kΩ ):
10 Hz - 70 kHz +/- 0.5 dB @ 0 dBU
Loss across transformer (at midband with termination as above):
0.3 dB
Core:
Mu-metal
Isolation between windings / between windings and shields:
3 kV / 1.5 kV
Data at different termination alternatives, showed on page 2 of this data sheet.
Termination
Alternative
Turns
ratio
Copper Resistance
prim/sec
Idle impedance
@40 Hz, 0dBU
Suggested Use
THD < 0.2%@40 Hz
primary level /
real source impedance
A
1:1
590
Ω / 590 Ω
80 k
Ω / 80 kΩ
10 k
Ω / 10 kΩ
22 dBU / 600
Ω
B
1:1
147
Ω / 147 Ω
20 k
Ω / 20 kΩ
600
Ω / 600 Ω
16 dBU / 150
Ω
C
1:2
147
Ω / 590 Ω
20 k
Ω / 80 kΩ
600
Ω / 2.5 kΩ
16 dbU / 150
Ω
D
1:2
37
Ω / 147 Ω
5 k
Ω / 20 kΩ
200
Ω / 1 kΩ
10 dBU / 37.5
Ω
E
1:4
37
Ω / 590 Ω
5 k
Ω / 80 kΩ
200
Ω / 3.2 kΩ
10 dBU / 37.5
Ω
F (Split)
2:1+1 590
Ω / 295 Ω + 295 Ω
G (Split)
1:1+1 147
Ω / 295 Ω + 295 Ω Left side can also be connected as B
CenterTap (1:1+1)
or D (1:2+2)
R000113
8
7
6
5
4
3
2
1
15
14
13
11
10
9
Can + Core
13
1
2
3
4
11
14
16
15
9
10
8
7
6
5
Tibeliusgatan 7
International
Domestic
S-761 50 NORRTÄLJE
Phone
+46 - 176 13930
0176-13930
SWEDEN
Fax
+46 - 176 13935
0176-13935
16
LL1545A
(top view)
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