Tibeliusgatan 7SE-761 50 NORRTÄLJE
SWEDENLUNDAHL
TRANSFORMERS

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Audio Transformer LL1544A
LL1544A is a line input / general purpose audio transformer which can be used in many different applications
ranging from bridging input to microphone input applications. The transformer is built up from two threesection coils with interleaved Faraday shields. The core is a two-component amorphous strip core. This coretype combines a high sensitivity for very low signal levels with excellent high-level capabilities. In addition, as
this type of core does not store energy (unlike conventional mu-metal cores), at low frequencies phase responseis excellent and resonance with a series capacitor is practically eliminated.
The LL1544A replaces previous types LL1544 and LL1554.
Turns ratio:
Dims: (Length x Width x Height above PCB (mm))
Pin Layout (viewed from pins side) and Windings Schematics:

1+1+1+1:2+230 x 22.5 x 14.5

1123456789101113
141516

293104811, 13, 14
can + core7166155
Spacing between pins:
Spacing between rows of pins:
Weight:Rec. PCB hole diameter:
Static resistance of each primary (average):
Static resistance of each secondary (average):
Self resonance point:
Recommended load for best square-wave response(Termination alternative A below):
Frequency response (source 600Ω ,load (6.7 kΩ + 470 pF) in parallel with 56 kΩ ):Loss across transformer (at 1kHz with termination as above):
Isolation between windings / between windings and shields:

2.54 mm (0.1")
22.86 mm (0.9")27 g
1.5 mm130 Ω260 Ω> 220 kHz
6.7 kΩ + 470 pF
10 Hz - 70 kHz +/- 0.5 dB @ 0 dBU
0.2 dB
3 kV / 1.5 kV

Data at different termination alternatives, showed on the following page:
Idle impedance
Suggested Use
Termination Alternative Turns Copper
ratio
Resistance@40 Hz, 0dBU
Prim/sec
R4B / R4U : L4B / L4U 1:1520Ω / 520Ω
80kΩ / 80kΩ
10 kΩ / 10 kΩ
R2B / R2U : L2B / L2U 1:1130Ω / 130Ω
20kΩ / 20kΩ
600Ω / 600Ω
R2B / R2U : L4B / L4U 1:2130Ω / 520Ω
20kΩ / 80kΩ
600Ω / 2.5 kΩ
R4B / R4U : L2B / L2U 2:1
520Ω / 130Ω
5kΩ / 20kΩ
10 kΩ / 2.5 kΩ
4:1
R4B / R4U : L1520Ω / 65Ω
80kΩ / 5kΩ
10 kΩ / 600Ω

THD < 0.5%@50 Hz
primary level / realsource impedance
20 dBU / 600Ω
14 dBU / 150Ω
14 dbU / 150Ω
22 dBU / 37.5Ω
22 dBU / 37.5Ω.
R030220

91011Connection alternatives for LL1544A
Component side view

1234567813
14
15
16

Component side view

Connection: R4B
Balanced sourceConnection: R4U
Unbalanced source

Connection: R2B
Balanced source

910119101191011131415161314151613141516Connection L4B
Balanced load

Connection L4U
Unbalanced load

Grounded atsourceConnection R2U
Unbalanced source
910111234567813141516

Grounded atsource12345678
Centertap

Connection L2U
Unbalanced load

Connection L2B
Balanced load

1234567812345678Connection L1

12345678

CentertapTurnsratio

Application

1:1
1:22:1
1:1
1:1
1:2
2:1
1:1

Line input to unbalanced circuits
Line input to unbalanced circuits
Line input to unbalanced circuits
Low impedance line input to unbalanced circuits
Line input to balanced circuits
Line input to balanced circuits
Line input to balanced circuits
Low impedance line input to balanced circuits

Transformer
Input (primary)
R4B / R4U
R2B / R2U
R4B / R4U
R2B / R2U
R4B / R4U
R2B / R2U
R4B / R4U
R2B / R2U

Transformer
Output(secondary)
L4U
L4U
L2UL2U
L4B
L4B
L2B
L2B