P6141 ETAL | Alldatasheet
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ETALDOC 856/3 Page 1 of 5 August 2004 PRODUCT DATA SHEET PLANAR POWER TRANSFORMER P6141 Features Applications ∗ Planar windings ∗ DC-DC converters ∗ 4mm height above PCB ∗ Forward converters ∗ Low leakage inductance ∗ 48V or 24V inputs ∗ High frequency operation ∗ 5V @ 5A output ∗ Externally configurable ∗ 3.3V @ 7A output ∗ Centre-tapped secondaries ∗ Lead-free (Pb-free)
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. 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.
ETALDOC 856/3 Page 2 of 5 August 2004 SPECIFICATIONS Electrical Typical values at T = 25ºC, unless otherwise stated. Parameter Conditions Min Typ Max Units Primary Inductance 100kHz, 100mV Each primary winding 2-9, 1-10 17 25 35 µH Leakage Inductance 500kHz, 100mV (1, 2) – (9, 10) link 3, 4, 5, 6, 7, 8 - - 100 nH Primary/Secondary voltage isolation 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 m Ω 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 0.514mm-1 Ve Effective volume 800mm3 le Effective length 20.3mm Ae Effective area 39.5mm2 µe Effective permeability 1270 m Mass 4.1g Transformer sc hematic Fig 1 4PRIM ARY 3 T PRIM ARY 3 T SEC O NDARY SEC O NDARY
ETALDOC 856/3 Page 3 of 5 August 2004 CONSTRUCTION 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. 19.2 11.7 7.0 9.8 7.0 9.8 12.0 4.24.2 7.97.9 R1.20Cu P ADS 2.0 x 2.4 (10x) PC B c u t o u t RECOMMENDED PCB LAYOUT (TOP VIE W) Connections Fig 3 V in SWITCH LO A D F orward converter with z ener diode res et Fig 4 Vz No te : V t > V t for flux to be fully resetz off in on Fig 5 V in SWI TCH LO A D SWI TCH Dimensions Fig 2 25.0 9.8 7.7 18.0 6.0 12.0 2.1 10.0 COR E Pi n 1 i d e n t Mounting pads : plated thr ough holes ø1.5 12 3 4 8910 P6141 CYYMM
ETALDOC 856/3 Page 4 of 5 August 2004 Input voltage setting For 48V operation, the P6141 primaries are connected in series, giving a nominal inductance of 100µH and primary DCR 41m Ω. 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 15m Ω. 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. 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. 48V input, 5V output Fig 6 48V 48V input, 3.3V output Fig 7 3.3V 48V 24V input, 5V output Fig 8 24V 24V input, 3.3V output Fig 9 3.3V 24V
ETALDOC 856/3 Page 5 of 5 August 2004 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: 2. Energy storage. The inductor must be able to store sufficient energy without saturation. Energy storage is given by: ½LI2 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 I sat = 6A Energy = 68.4µJ ORDERING CODE ABSOLUTE MAXIMUM RATINGS P6141T (Ratings of components independent of circuit). Short term isolation voltage (1s) 500Vrms V.µs per primary winding 16V.µs (for ΔB=135mT) Storage temperature +85ºC Magnetic Core temperature 120ºC Tape and Reel (400 parts per 13” reel) Type code Reflow temperature (10s) 260ºC 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 FM 25326 ISO 9001 0.3Vout Lmin ≈ Iout (min) f