User Manual

Line Input Transformer
LL1540
LL1540 is a high impedance, high level line input transformer.
The transformer consists of two coils, each with one primary and one secondary part separated by a electrostatic
shield. The core is a high permeability mu-metal core, and the transformer is housed in a mu-metal can.
Being a high impedance transformer, the LL1540 should normally be used in a series-series connection.
Turns ratio: 1 + 1 : 1 + 1
Dims (Length x Width x Height above PCB (mm)): 38 x 24 x 17
Pin layout (viewed from component side) and winding schematics:
Spacing between pins: 5.08 mm (0.2")
Spacing between rows of pins: 27.94 mm (1.1")
Offset of earth pin from adjacent row: 2.54 mm (0.1")
Weight: 47 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each primary: 610
Ω
Static resistance of each secondary: 800
Ω
Distortion (source impedance 600
Ω
): + 20 dBU < 0.1% @ 50 Hz
+30 dBU < 1 % @ 50 Hz
Self resonance point : > 60 kHz
Recommended load for best square-wave response: 22 k
Ω
in series with 1nF
Frequency response (source 600
Ω
, load 15 k
Ω
) 5 Hz -- 50 kHz +/- 0.2 dB
Loss across transformer (at 1 kHz with above termination): 0.5 dB
Isolation between windings / between windings and shield: 4 kV / 2 kV
Suggested connections:
R980616
3
2
1
8
7
6
4
5
E
E
2
1
3
4
6
5
7
8
3
2
1
8
7
6
4
5
E
+
+
R/2
22 k
1 nF
R/2
LL1540
Suggested connection for symmetric input
amplifier (recommended for very high CMRR).
Select R for desired input impedance.
With R < 25 k, RC network can be omitted.
Suggested connection for asymmetric input amplifier.
2 x 12 k resistors required for > 60 dB CMRR.
3
2
1
8
7
6
4
5
E
+
+
12k
12k
LL1540


Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
LL1540
(top view)