8

VP

VERSA-PAC® Inductors and Transformers (Surface Mount)

5V to 3.3V Buck Converter With 5V Output

This circuit minimizes both board space and cost by eliminating a

second regulator.

VERSA-PAC’s gap serves to prevent core

saturation during the switch on-time and also stores energy for the

+5V load which is delivered during the flyback interval. The +3.3V

buck winding is configured by placing two windings in series while

the +5V is generated by an additional flyback winding stacked on

the 3.3V output. Extra windings are paralleled with primary

windings to handle more current. The turns ratio of 2:1 adds 1.67V

to the +3.3V during the flyback interval to achieve +5V.

+3.3V@

12.5A

+V

RTN

VERSA-PAC

VP5-0083

12

11

10

9

8

7

1

2

3

4

5

6

Synchronous

Controller

IC

+

V

+

+5V@

1A

+3.3V@

4.2A

+

RTN

VERSA-PAC

VP5-0083

LEVEL SHIFT

12,11

1,2

7

6

10,9,8

3,4,5

Synchronous

Controller

IC

+

3.3V Buck Converter

This circuit utilizes the gap of the VP5-0083 to handle the 12.5

Amp output current without saturating. In each of the five

VERSA-

PAC sizes, the gap is varied to achieve a selection of specific

inductance and current values (see

VERSA-PAC Data Table).

All six windings are connected in parallel to minimize AC/DC

copper losses and to maximize heat dissipation. With

VERSA-

PAC, this circuit works well at or above 300 KHz. Also, the closed

flux-path EFD geometry enables much lower radiation

characteristics than open-path bobbin core style components.

LITHIUM-ION BATTERY TO 3.3V SEPIC CONVERTER

The voltage of a Lithium-Ion Battery varies above and below

+3.3V depending on the degree of charge. The SEPIC

configuration takes advantage of

VERSA-PAC’s multiple tightly

coupled windings. This results in lower ripple current which lowers

noise and core losses substantially. The circuit does not require a

snubber to control the voltage “spike” associated with switch turn-

off, and is quite efficient due to lower RMS current in the windings.

+3.3V@

6A

VERSA-PAC

VP5-0083

12 11 10

12 3

987

45

+

+

+

6

Controller

IC

W/Integral

Switch

100

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

200

300

400

500

VP 5

VP 4

VP 3

VP 2

VP 1

Frequency, kHz

100

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

200

300

400

500

VP 5

VP 4

VP 3

VP 2

Bipolar (Push-Pull) Power vs Frequency

Frequency, kHz

Unipolar (Flyback) Power vs Frequency

Technical Data 4301

Effective August 2017

VERSA-PAC® Performance characteristics

VP 1

OCL vs. Isat

100.0%

90.0%

80.0%

70.0%

60.0%

50.0%

40.0%

30.0%

20.0%

10.0%

0.0%

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

120.0%

140.0%

160.0%

180.0%

200.0%

% of Isat

These curves represent typical power handling capability.

Indicated power levels may not be achievable with all configurations.

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