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
V
VERSA-PAC
VP5-0083
V
12
11
10
9
8
7
1
2
3
4
5
6
Synchronous
Controller
IC
C
+
+V
+5V@
1A
+3.3V@
4.2A
+
RTN
+
VERSA-PAC
VP5-0083
V
LEVEL SHIFT
1
2,11
1,2
7
6
10,9,8
3,4,5
S
ynchronous
C
ontroller
I
C
+
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 lo
w
er RMS current in the windings
.
+3.3V@
6A
R
VERSA-PAC
VP5-0083
1
12 11 10
123 987
45
+
+
+
6
Controller
IC
W/Integral
Switch
Watts
Frequency, kHz
100
0.0
1
0.0
20.0
30.0
4
0.0
50.0
60.0
70.0
200 300 400 500
VP 5
VP 4
VP 3
VP 2
VP 1
Watts
F
requency, kHz
A
1
00
0.0
5.0
10.0
15.0
2
0.0
2
5.0
3
0.0
35.0
40.0
2
00 300 400 500
V
P 5
VP 4
VP 3
VP 2
VP 1
S
Bipolar (Push-Pull) Power vs Frequency Unipolar (Flyback) Power vs Frequency
VERSA-PAC
®
Performance Characteristics
These curves represent typical power handling capability.
Indicated power levels may not be achievable with all configurations.
VERSA-PAC
®
Inductors and Transformers
(Surface Mount)
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1225 Broken Sound Pkwy. Suite F Boca Raton, FL 33487
Tel:
+1-561-998-4100 Toll Free: +1-888-414-2645 Fax: +1-561-241-6640
This bulletin is intended to present product design solutions and technical information that will help the end user with design applications. Cooper Electronic
Technologies reserves the right, without notice, to change design or construction of any products and to discontinue or limit distribution of any products. Cooper
Electronic Technologies also reserves the right to change or update, without notice, any technical information contained in this bulletin. Once a product has been
selected, it should be tested by the user in all possible applications.
Life Support Policy: Cooper Electronic T
echnologies does not authorize the use of any of its products for use in life support devices or systems without the
express written approval of an officer of the Company
. Life support systems are devices which support or sustain life, and whose failure to per
form, when
properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injur
y to the user
.
PM-4301 3/07
© Cooper Electronic
Technologies 2007
