
Audio Output Transformer
LL2811
LL2811 is an audio output transformer for balanced drive, with the following features:
1.
Four section winding structure for small leakage inductance.
2.
Ideally used 2 : 1 (secondaries in parallel) with e.g. NE5532 op amps for low noise.
3.
Precision made audio C core for small size.
4.
Two-coil structure and mu-metal housing for high magnetic noise immunity.
5.
Designed to fit three in a row across a Euroboard.
The secondaries can be connected in parallel for low output impedance or in series for high output level.
Turns ratio: 1 + 1: 1 + 1
Dims: (Length x Width x Height above PCB (mm)) 31 x 26x 23
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: 65 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each
primary (average): 45 Ω
Static resistance of each
secondary (average): 45 Ω
Max. primary level (primaries in series) +30 dBU @ 50 Hz
Leakage inductance (windings in series): < 1 mH
No-load impedance(primaries in series, primary level):> 750 Ω @ 50 Hz, +20 dBU
Balance of output (according to IRT, source < 10 Ω , Load 600 Ω): > 55 dB
Frequency response (source 10 Ω, load 600 Ω,
0 dBU): 10 Hz -- 100 KHz +/- 0.3 dB
Isolation between primary and secondary windings/
between windings and core: 4 kV / 2 kV
Fundamental design of driving circuitry, mixed feedback, 2:1, suggested by A. Offenberg, NRK
8 16
7
6
3
2
1
15
14
13
11
10
9
Can + Core 13
R
R
R1
R1 is approximately 90 ohms.
Select R1 for good THD at LF and
for good square wave response.
8 16
7
6
3
2
1
15
14
13
11
10
9
+ out
- out
+ in
R980626
91
11
3
168
146
Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
LL2811