Datasheet
General Purpose Transformers
LL1527 and LL1527XL
LL1527 is a truly general purpose transformer for microphone or line input, for output and for galvanic isolation of
units. LL1527 has been generally accepted by the audio industry as the general purpose audio transformer.
The LL1527 is built-up from two coils, each with one primary and one secondary winding separated by an electrostatic
shield. The core is a high permeability mu metal core. The transformer is housed in a mu-metal can.
In the LL1527XL, the core is about 45% larger than in the LL1527, resulting in a larger level capability.
Turns ratio: 1 + 1 : 1 + 1
Pin layout (viewed from component side) and winding schematics:
Spacing between pins Spacing between rows of pins Offset of earth pin from adjacent row:
5.08 mm (0.2") 27.94 mm (1.1") 2.54 mm (0.1")
LL1527 LL1527XL
Dimensions (L x W x H above PCB, in mm) 38 x 24 x 17 38 x 24 x 20.5
Weight:
48 g 65 g
Rec. PCB hole diameter:
1.5 mm 1.5 mm
Static resistance of each primary:
43
Ω
54
Ω
Static resistance of each secondary:
56
Ω
67
Ω
Distortion (primaries connected in series, source
impedance 800
Ω
):
+ 6 dBU 0.1% @ 50 Hz + 9 dBU 0.1% @ 50 Hz
+16 dBU < 1 % @ 50 Hz +19 dBU < 1 % @ 50 Hz
Self resonance point :
> 200 kHz > 200 kHz
Optimum load for best square-wave response
(sec. in series):
3 - 4 k
Ω
3 - 4 k
Ω
Frequency response (source 800
Ω
, load 4 k
Ω
serial connection):
10 Hz -- 150 kHz +/- 0.2 dB 10 Hz -- 150 kHz +/- 0.2 dB
Loss across transformer (at midband, with
above termination):
0.4 dB 0.5 dB
Isolation between windings/ between windings
and shield:
4 kV / 2 kV 4 kV / 2 kV
Connection alternatives and suggested applications:
Parallel-split connection
(1 : 1 + 1)
3
2
1
8
7
6
4
5
E
3
2
1
8
7
6
4
5
E
+
+
3
2
1
8
7
6
4
5
E
+
+
3
2
1
8
7
6
4
5
E
+
+
3
2
1
8
7
6
4
5
E
+
+
+
Parallel-parallel connection (1 : 1)
(e.g. mic input)
Serial-serial connection (1 : 1)
for line input
Parallel-serial connection (1 : 2)
(e.g. mic. input)
Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
R980616
E
2
1
3
4
6
5
7
8
LL1527
(top view)