DS1227 Datasheet, PDF(12/20 Page) Dallas Semiconductor

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DS1227 Datasheet, PDF (12/20 Pages) Dallas Semiconductor – KickStarter Chip

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DS1227

mounts directly onto a printed circuit board by its leads.

Such devices offer high efficiency and mounting ease,

but at a somewhat higher cost than molded inductors.

Ferrite Cores (Pot Cores)

Pot cores are very popular as switch-mode power sup-

ply applications since they offer high performance and

ease of design. The coils are generally wound on a plas-

tic bobbin, which is then placed between two pot core

sections. A simple clip to hold the core sections together

completes the inductor. Smaller pot cores mount direct-

ly onto printed circuit boards via the bobbin terminals.

Cores come in a wide variety of sizes often with the cen-

ter posts ground down to provide an air gap. The gap

prevents saturation while accurately defining the induc-

tance per turn squared.

Pot cores are suitable for all DC-DC converters, but are

usually used in the higher power applications. They are

also useful for experimentation since it is easy to wind

coils onto the plastic bobbins.

Toroidal Cores

In volume production, the toroidal core offers high per-

formance, low size and weight, and low cost. They are,

however, slightly more difficult for prototyping, in that

manually winding turns onto a toroid is more tedious

than on the plastic bobbins used with pot cores. Toroids

are more efficient for a given size since the flux is more

evenly distributed than in a pot core, where the effective

core area differs between the post, side, top, and bot-

tom.

Since it is difficult to gap a toroid, manufacturers pro-

duce toroids using a mixture of ferromagnetic powder

(typically iron or Mo-Permalloy powder) and a binder.

The permeability is controlled by varying the amount of

binder, which changes the effective gap between the

ferromagnetic particles. Mo-Permally powder (MFP)

cores have lower losses and are recommended for the

highest efficiency, while iron powder cores are lower

cost.

COIL AND CORE MANUFACTURERS Table 1

TYPE

TYPICAL

MANUFACTURER

PART #

Molded

Potted Toroidal

Toroidal Core

Ferrite Core

Dale

Cadell-Burns

Gowanda

Nytronics

TRW

Dale

Gowanda

TRW

Torotel Prod.

Allen Bradley

Siemans

Magnetics

Stackpole

Magnetics

1HA-104

7070-29

1B253

WEE-470

LL-500

TE-3Q4TA

050AT1003

MH-1

PT 53-18

T0451S100A

B64290-K38-X38

555130

57-3215

G-41408-25

DESCRIPTION

500 ÂµH, 0.5 ohms

220 ÂµH, 0.55 ohms

250 ÂµH, 0.44 ohms

470 ÂµH, 10 ohms

500 ÂµH, 0.75 ohms

1 mH, 0.82 ohms

100 ÂµH, 0.05 ohms

600 ÂµH, 1.9 ohms

500 uH, 5 ohms

500 nH/T2

4 ÂµH/T2

53 nH/T2

14 mm x 8 mm

14 x 8, 250 nH/T2

Note:

This list does not constitute an endorsement by Dallas Semiconductor and is not intended to be a

comprehensive list of all manufacturers of these components.

022698 12/20

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