Zakładka z wyszukiwarką danych komponentów |
|
ADP3164JRU-REEL Arkusz danych(PDF) 9 Page - ON Semiconductor |
|
ADP3164JRU-REEL Arkusz danych(HTML) 9 Page - ON Semiconductor |
9 / 15 page REV. 0 ADP3164 –9– APPLICATION INFORMATION The design parameters for a typical VRM 9.1-compliant CPU application are as follows: Input voltage (VIN) = 12 V VID setting voltage (VVID) = 1.475 V Nominal output voltage at no load (VONL) = 1.4605 V Nominal output voltage at 80 A load (VOFL) = 1.3845 V Static output voltage drop based on a 0.95 m load line (ROUT) from no load to full load (V ) = VONL – VOFL = 1.4605 V – 1.3845 V = 76 mV Maximum Output Current (IO) = 81 A Number of Phases (n) = 4 CT Selection—Choosing the Clock Frequency The ADP3164 uses a fixed-frequency control architecture. The frequency is set by an external timing capacitor, CT. The clock frequency determines the switching frequency, which relates directly to switching losses and the sizes of the inductors and input and output capacitors. A clock frequency of 800 kHz sets the switching frequency of each phase, fSW, to 200 kHz, which represents a practical trade-off between the switching losses and the sizes of the output filter components. To achieve an 800 kHz oscillator frequency, the required timing capacitor value is 100 pF. For good frequency stability and initial accuracy, it is recom- mended to use a capacitor with low temperature coefficient and tight tolerance, e.g., an MLC capacitor with NPO dielec- tric and with 5% or less tolerance. Inductance Selection The choice of inductance determines the ripple current in the inductor. Less inductance leads to more ripple current, which increases the output ripple voltage and the conduction losses in the MOSFETs, but allows using smaller-size inductors and, for a specified peak-to-peak transient deviation, output capacitors with less total capacitance. Conversely, a higher inductance means lower ripple current and reduced conduction losses, but requires larger-size inductors and more output capacitance for the same peak-to-peak transient deviation. In a 4-phase con- verter, a practical value for the peak-to-peak inductor ripple current is under 50% of the dc current in the same inductor. A choice of 50% for this particular design example yields a total peak-to-peak output ripple current of 8% of the total dc output current. The following equation shows the relationship between the inductance, oscillator frequency, peak-to-peak ripple current in an inductor and input and output voltages. L VV V Vf I IN OUT OUT IN SW L RIPPLE (– ) () (1) For 10 A peak-to-peak ripple current, which is 50% of the 20 A full-load dc current in an inductor, Equation 1 yields an inductance of: L VV V V kHz A nH (– . ) . 12 1 475 1 475 12 800 4 10 646 A 600 nH inductor can be used, which gives a calculated ripple current of 10.8 A at no load. The inductor should not saturate at the peak current of 26 A, and should be able to handle the sum of the power dissipation caused by the average current of 20 A in the winding and the core loss. The output ripple current is smaller than the inductor ripple current due to the four phases partially canceling. This can be calculated as follows: I nV V n V VL f I VV V V nH kHz A O OUT IN OUT IN OSC O (– ) . (– . ) . 4 1 475 12 4 1 475 12 600 800 625 (2 Designing an Inductor Once the inductance is known, the next step is either to design an inductor or find a standard inductor that comes as close as possible to meeting the overall design goals. The first decision i designing the inductor is to choose the core material. There are several possibilities for providing low core loss at high frequencies. Two examples are the powder cores (e.g., Kool-M ® from Magnetics, Inc.) and the gapped soft ferrite cores (e.g., 3F3 or 3F4 from Philips). Low frequency powdered iron cores should be avoided due to their high core loss, especially when the induc- tor value is relatively low and the ripple current is high. Two main core types can be used in this application. Open magnetic loop types, such as beads, beads on leads, and rods and slugs, provide lower cost but do not have a focused mag- netic field in the core. The radiated EMI from the distributed magnetic field may create problems with noise interference in the circuitry surrounding the inductor. Closed-loop types, such as pot cores, PQ, U, and E cores, or toroids, cost more, but have much better EMI/RFI performance. A good compromise between price and performance are cores with a toroidal shape. There are many useful references for quickly designing a power inductor. Table II gives some examples. Table II. Magnetics Design References Magnetic Designer Software Intusoft (http://www.intusoft.com) Designing Magnetic Components for High-Frequency DC-DC Converters McLyman, Kg Magnetics ISBN 1-883107-00-08 Selecting a Standard Inductor The companies listed in Table III can provide design consulta- tion and deliver power inductors optimized for high power applications upon request. Table III. Power Inductor Manufacturers Coilcraft (847)639-6400 http://www.coilcraft.com Coiltronics (561)752-5000 http://www.coiltronics.com Sumida Electric Company (408)982-9660 http://www.sumida.com Rev. 1 | Page 9 of 15 | www.onsemi.com Rev. 2 | Page 9 of 15 | www.onsemi.com |
Podobny numer części - ADP3164JRU-REEL |
|
Podobny opis - ADP3164JRU-REEL |
|
|
Link URL |
Polityka prywatności |
ALLDATASHEET.PL |
Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |