Linear Technology Analog Devices LT8301 Datasheet page 11

APPLICATIONS INFORMATION
In general, choose a transformer with its primary mag-
netizing inductance about 30% larger than the minimum
values calculated above. A transformer with much larger
inductance will have a bigger physical size and may cause
instability at light load.
Selecting a Transformer
Transformer specification and design is perhaps the most
critical part of successfully applying the LT8301. In addi-
tion to the usual list of guidelines dealing with high fre-
quency isolated power supply transformer design, the
following information should be carefully considered.
Table 1. Predesigned Transformers—Typical Specifications
TRANSFORMER DIMENSIONS
PART NUMBER (W × L × H) (mm)
750313973 15.24 × 13.34 × 11.43
750370047 13.35 × 10.8 × 9.14
750313974 15.24 × 13.34 × 11.43
750313970 15.24 × 13.34 × 11.43
750310799 9.14 × 9.78 × 10.54
750313972 15.24 × 13.34 × 11.43
750313975 15.24 × 13.34 × 11.43
750313976 15.24 × 13.34 × 11.43
12387-T036 15.5 × 12.5 × 11.5
12387-T037 15.5 × 12.5 × 11.5
12387-T040 15.5 × 12.5 × 11.5
12387-T041 15.5 × 12.5 × 11.5
12387-T038 15.5 × 12.5 × 11.5
12387-T039 15.5 × 12.5 × 11.5
PA3948.003NL 15.24 × 13.08 × 11.45
PA3948.004NL 15.24 × 13.08 × 11.45
PA3948.001NL 15.24 × 13.08 × 11.45
PA3948.002NL 15.24 × 13.08 × 11.45
PA3948.005NL 15.24 × 13.08 × 11.45
PA3948.006NL 15.24 × 13.08 × 11.45
L L R
PRI LKG
(µH) (µH) NP:NS (mΩ)
40 1 4:1
30 1 3:1:1
40 1 3:1
40 1 2:1
25 0.125 1:1:0.33
40 1 1:1
40 1 1:2 110
40 1 1:4 110
40 2 4:1 160
40 2 3:1 210
40 1.5 2:1 210
40 1.5 1:1 210
40 2 1:2 220
40 2 1:4 220
40 1.45 4:1 210
40 1.95 3:1 220
40 1.45 2:1 410
40 1.45 1:1 405
40 1.60 1:2 220
40 1.65 1:4 220
For more information
Analog Devices has worked with several leading magnetic
component manufacturers to produce pre-designed fly-
back transformers for use with the LT8301. Table 1 shows
the details of these transformers.
Turns Ratio
Note that when choosing the R
voltage, the user has relative freedom in selecting a trans-
former turns ratio to suit a given application. In contrast,
the use of simple ratios of small integers, e.g., 3:1, 2:1,
1:1, provides more freedom in settling total turns and
mutual inductance.
R
PRI SEC
(mΩ) VENDOR
80 40 Würth Electronik
60 12.5 Würth Electronik
80 50 Würth Electronik
80 70 Würth Electronik
60 74 Würth Electronik
80 185 Würth Electronik
865 Würth Electronik
2300 Würth Electronik
25 Sumida
30 Sumida
50 Sumida
200 Sumida
460 Sumida
2200 Sumida
26 Pulse Engineering
29 Pulse Engineering
70 Pulse Engineering
235 Pulse Engineering
1275 Pulse Engineering
3350 Pulse Engineering
www.analog.com
LT8301
resistor to set output
FB
TARGET APPLICATIONS
V (V) V (V) I (A)
IN OUT OUT
8 to 36 3.3 0.80
8 to 32 5 0.55
8 to 36 5 0.55
18 to 42 3.3 0.75
8 to 30 12 0.22
18 to 42 5 0.42
8 to 36 24 0.12
8 to 32 48 0.05
8 to 36 3.3 0.80
8 to 36 5 0.55
18 to 42 3.3 0.75
18 to 42 5 0.42
8 to 36 24 0.12
8 to 32 48 0.05
8 to 36 3.3 0.80
8 to 36 5 0.55
18 to 42 3.3 0.75
18 to 42 5 0.42
8 to 36 24 0.12
8 to 32 48 0.05
Rev. A
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