ETAL P6141T

PRODUCT DATA SHEET
PLANAR POWER TRANSFORMER
Features
Applications
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Planar windings
4mm height above PCB
Low leakage inductance
High frequency operation
Externally configurable
Centre-tapped secondaries
Lead-free (Pb-free)
P6141
DC-DC converters
Forward converters
48V or 24V inputs
5V @ 5A output
3.3V @ 7A output
DESCRIPTION
P6141 is a planar power transformer using
multilayer PCB technology. It is intended for low
profile high frequency DC-DC forward converters up
to 500kHz. With careful design, output power
exceeding 30W is achievable.
P6141 has split primaries and secondaries enabling
the device to be configured for 48V and 24V inputs
and 5V or 3.3V outputs.
ETALDOC 856/3
Page 1 of 5
The contacts to the host circuit board are made
by solder connection to large plated-through
holes in the P6141 PCB, thus ensuring low
resistance connection. The ferrite is intended to
sit within a PCB cut-out, giving a height above
board of 4mm.
P6141 is lead-free (Pb-free) and suitable for
conventional and lead-free processing.
August 2004
P6141
SPECIFICATIONS
Electrical
Typical values at T = 25ºC, unless otherwise stated.
Parameter
Conditions
Min
Typ
Max
Units
17
25
35
µH
-
-
100
nH
500
-
-
Vrms
Primary Inductance
100kHz, 100mV
Each primary winding
2-9, 1-10
Leakage Inductance
500kHz, 100mV
(1, 2) – (9, 10)
link 3, 4, 5, 6, 7, 8
Primary/Secondary
voltage isolation
(1+2):3
Interwinding capacitance
100kHz, 1V
primary : secondary
-
308
-
pF
Total transformer losses
Vout = 5V at Iout = 5A or
Vout = 3.3V at Iout = 7A
400kHz
-
0.7
-
W
DCR
Primaries
2-9, 1-10
17
20
23
mΩ
3-5, 6-8
-
7.5
-
mΩ
Turns Ratio
(1-10):(2-9)
(5-3):(8-6)
(1-10):(5-3)
(2-9):(8-6)
-
1.0
1.0
1.5
1.5
-
-
Operating range:
Functional
Storage
Ambient temperature
-40
-40
-
+85
+85
ºC
ºC
Typical Magnetic Core Coefficients
C1
Core factor
Transformer sc hematic
-1
0.514mm
Fig 1
3
Ve
Effective volume
le
Effective length
Ae
Effective area
µe
m
Effective permeability
39.5mm
1270
Mass
4.1g
1
800mm
20.3mm
PRIMARY
3T
4
1T
2
10
PRIMARY
8
3T
1T
7
1T
Page 2 of 5
SECONDARY
3
2
9
ETALDOC 856/3
5
1T
SECONDARY
6
August 2004
P6141
CONSTRUCTION
Dimensions
Connections
Fig 3
25.0
12.0
9.8
19.2
5
PCB c utout
7.9
4
CORE
Mounting pads: plated through holes ø1.5
11.7
10.0
2.1
7.0
4.2
CYYMM
7.7
18.0
9.8
7.0
6
3
1 2
9.8
Pin 1 ident
12.0
7
7.9
8
P6141
10 9
Cu PADS 2.0 x 2.4 (10x)
R1
.
4.2
Fig 2
20
6.0
RECOMMENDED PCB LAYOUT (TOP VIEW)
Dimensions shown are in millimetres.
Terminal finish is 0.1µm max gold (Au) over nickel (Ni).
APPLICATION SCHEMATICS
P6141 is designed for forward converter applications where power is coupled from the primary to secondary
circuits during the ‘on’ time of the switch. Unlike the flyback converter, the forward converter transformer is
not designed as a storage element, and thus the ferrite core is ungapped.
In the single quadrant operation forward converter, some means must be provided to ‘reset’ the flux due to
the build up of magnetizing current in the device, and since P6141 does not have a reset winding, this
function must be provided externally.
There are several methods for providing the reset function in the absence of a reset winding.
The first, shown in fig 4, uses a zener diode to perform the reset function. This has the advantage of simplicity;
however, energy is wasted in the reset circuit, and there is a constraint on the duty cycle that must be
observed.
An alternative circuit is shown in fig 5, where two synchronized switches are used. This has the advantage
that energy is returned to the supply; however, the duty factor is limited to 0.5.
Forward converter with zener diode reset
Fig 5
Fig 4
+
SWITCH
LOAD
+
V in
–
Vz
–
+
+
V in
LOAD
–
SWITCH
–
SWITCH
Note: Vz toff > Vin ton for flux to be fully reset
ETALDOC 856/3
Page 3 of 5
August 2004
P6141
Input voltage setting
For 48V operation, the P6141 primaries are connected in series, giving a nominal inductance of 100µH and
primary DCR 41mΩ. For 24V operation, the primaries are connected in parallel, giving a nominal primary
inductance of 25µH and primary DCR of 10mΩ
Output voltage setting
For 5V output, the P6141 secondaries are connected in series, giving a secondary DCR of 15mΩ. For 3.3V
operation, the secondaries are connected in parallel, giving a secondary DCR of 3.8mΩ.
Figs 6-9 show forward converter topologies with input voltages 48V and 24V and output voltages 5V and
3.3V.
48V input, 5V output
48V input, 3.3V output
Fig 6
Fig 7
1
5
1
4
+
48V
–
10
2
3
8
7
9
4
+
+
5V
–
48V
–
10
3
2
8
7
6
9
24V input, 5V output
24V input, 3.3V output
Fig 8
Fig 9
1
1
5
24V
–
10
2
3
8
7
9
+
3.3V
–
6
5
4
4
+
5
+
+
5V
–
6
24V
–
10
3
2
8
7
9
+
3.3V
–
6
For frequencies from 300—500kHz and output currents from 1–5A (5V output) and 1.5–7A (3.3V output)
suitable low profile output inductors (height 4mm) can be found in the ETAL P7602-1003 range. See below
for choice of output inductor.
ETALDOC 856/3
Page 4 of 5
August 2004
P6141
Output inductor
Unless they are current fed, forward converters require output inductors.
Suitable standard power inductors are available from the ETAL range. The inductor must satisfy a number of
criteria (apart from mechanical considerations) as follows:1. Minimum inductance.
It is essential that the current through the inductor does not fall to zero, which places a constraint that the
pk-pk ripple current must not exceed twice the minimum output current. Once the minimum output
current (Iout) is defined, the minimum inductance (Lmin) as a function of frequency (f) and output voltage
(Vout) can be defined thus:
Lmin ≈
0.3Vout
Iout (min) f
2. Energy storage.
The inductor must be able to store sufficient energy without saturation.
Energy storage is given by:
½LI
2
out
Profec publishes application data on its ETAL inductors showing, by product family, typical inductance
ranges and storage energies.
As a check, it is worth verifying from individual datasheets that maximum current (maximum load current
+ ripple current) does not exceed the saturation current rating.
As an example, for the 5V/5A output and minimum output current of 1A with switching frequency 400kHz,
the minimum inductance calculated is 3.75µH and energy storage requirement 47µJ.
A low profile (4mm) shielded power inductor P7602-1003-3R8Y will be suitable. It has the following
characteristics:
L=
3.8µH
Isat =
6A
Energy = 68.4µJ
ORDERING CODE
ABSOLUTE MAXIMUM RATINGS
(Ratings of components independent of circuit).
P6141T
Tape and Reel
(400 parts per 13” reel)
Type code
Short term isolation voltage (1s)
500Vrms
V.µs per primary winding
16V.µs
Storage temperature
+85ºC
Magnetic Core temperature
120ºC
Reflow temperature (10s)
260ºC
(for ΔB=135mT)
ETAL Group Oy, Kuormatie 14, FIN-03101, Nummela
Telephone: +358 (0)20 7500 330
Fax: +358 (0)20 7500 333
Website: www.etalgroup.com
Email: etalgroup@egruppen.com
ETALDOC 856/3
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ISO 9001
FM 25326
August 2004