ML4812CX Ver la hoja de datos (PDF) - Micro Linear Corporation
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ML4812CX Datasheet PDF : 16 Pages
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TYPICAL APPLICATIONS (Continued)
MATERIAL
Powdered Iron
Powdered Iron
Molypermalloy
MANUFACTURER
Micrometals
Micrometals
SPANG (Mag. Inc.)
PART #
T225-8/90
T184-40
58076-A2 (high flux)
Table 1. Toroidal Cores (L1)
ML4812
TURNS (#24AWG)
200
120
180
MAGNETICS TIPS
L1 — Main Inductor
As shown in Table 1, one of several toroidal cores can be
used for L1. The T184-40 core above is the most
economical, but has lower inductance at high current.
This would yield higher ripple current and require more
line EMI filtering. The value for RSC (slope compensation
resistor on RAMP COMP) was calculated for the T225-8/
90 and should be recalculated for other inductor
characteristics. The various core manufacturers have a
range of applications literature available. A gapped ferrite
core can also be used in place of the powdered iron core.
One such core is a Philips Components (Ferroxcube) core
#4229PL00-3C8. This is an ungapped core. Using 145
turns of #24 AWG wire, a total air gap of 0.180" is
required to give a total inductance of about 2mH. Since
1/2 of the gap will be on the outside of the core and 1/2
the gap on the inside, putting a 0.09" spacer in the center
will yield a 0.180" total gap. To prevent leakage fields
from generating RFI, a shorted turn of copper tape should
be wrapped around the gap as shown in Figure 11. For
production, a gapped center leg can be ordered from most
core vendors, eliminating the need for the external
shorted copper turn when using a potentiometer core.
T1 — Sense Transformer
In addition to the core type mentioned in the parts list, the
following Siemens cores should be suitable for
substitution and may be more readily available in Europe.
MATERIAL
N27
N30
SIZE CODE
R16/6.3
R16/6.3
PART #
B64290-K45-X27
B64290-K45-X830
The N27 material is for high frequency and will work
better above 100KHz but both are adequate. In addition,
Philips Components (Ferroxcube) core 768T188-3C8 can
be used. Please also refer to the list of core vendors below
SPANG/Magnetics Inc.
Micrometals
Philips Components
1 (800) 245-3984, or
(412) 282-8282
1 (800) 356-5977
(914) 247-2064
COPPER FOIL
SHORTED TURN
0.09" GAP
Figure 11. Copper Foil Shorted Turn
11
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