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 in the PDF section above.
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: 610W
Static resistance of each secondary: 800W
Distortion (source impedance 600W ): + 20 dBU < 0.1% @ 50 Hz
+30 dBU < 1 % @ 50 Hz
Self resonance point : > 60 kHz
Recommended load for best square-wave response: 22 kW in series with 1nF
Frequency response (source 600W, load 15 k W ) 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 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.
Suitable transformer for 1:1 applications with 600 ohm source and at least 10K reflecting impedance output 600/10K.
Lundahl LL1540 high level line input transformer
