数据搜索系统,热门电子元器件搜索 |
|
FAN53601 数据表(PDF) 11 Page - Fairchild Semiconductor |
|
FAN53601 数据表(HTML) 11 Page - Fairchild Semiconductor |
11 / 14 page © 2010 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN53601 / FAN53611 • Rev. 1.0.1 11 Applications Information Selecting the Inductor The output inductor must meet both the required inductance and the energy-handling capability of the application. The inductor value affects average current limit, the PWM-to- PFM transition point, output voltage ripple, and efficiency. The ripple current (∆I) of the regulator is: SW OUT IN IN OUT f L V V V V I (5) The maximum average load current, IMAX(LOAD), is related to the peak current limit, ILIM(PK), by the ripple current, given by: 2 I I I ) PK ( LIM ) LOAD ( MAX (6) The transition between PFM and PWM operation is determined by the point at which the inductor valley current crosses zero. The regulator DC current when the inductor current crosses zero, IDCM, is: 2 I IDCM (7) The FAN53601/11 is optimized for operation with L = 470 nH, but is stable with inductances up to 1 H (nominal). The inductor should be rated to maintain at least 80% of its value at ILIM(PK). Efficiency is affected by the inductor DCR and inductance value. Decreasing the inductor value for a given physical size typically decreases the DCR; but because ∆I increases, the RMS current increases, as do the core and skin effect losses. 12 I I I 2 2 ) DC ( OUT RMS (8) The increased RMS current produces higher losses through the RDS(ON) of the IC MOSFETs, as well as the inductor DCR. Increasing the inductor value produces lower RMS currents, but degrades transient response. For a given physical inductor size, increased inductance usually results in an inductor with lower saturation current and higher DCR. Table 1 shows the effects of inductance higher or lower than the recommended 1 H on regulator performance. Output Capacitor Table 2 suggests 0402 capacitors. 0603 capacitors may further improve performance in that the effective capacitance is higher. This improves transient response and output ripple. Increasing COUT has no effect on loop stability and can therefore be increased to reduce output voltage ripple or to improve transient response. Output voltage ripple, ∆VOUT, is: OUT SW 2 OUT SW L OUT C f 8 1 D 1 D 2 ESR C f I V (9) Input Capacitor The 2.2 F ceramic input capacitor should be placed as close as possible between the VIN pin and GND to minimize the parasitic inductance. If a long wire is used to bring power to the IC, additional “bulk” capacitance (electrolytic or tantalum) should be placed between CIN and the power source lead to reduce the ringing that can occur between the inductance of the power source leads and CIN. The effective capacitance value decreases as VIN increases due to DC bias effects. Table 1. Effects of Changes in Inductor Value (from 470nH Recommended Value) on Regulator Performance Inductor Value IMAX(LOAD) ∆VOUT Transient Response Increase Increase Decrease Degraded Decrease Decrease Increase Improved Table 2. Recommended Passive Components and their Variation Due to DC Bias Component Description Vendor Min. Typ. Max. L1 470 nH, 2012,90 mΩ, 1.1 A Murata LQM21PNR47MC0 Murata LQM21PNR54MG0 Hitachi Metals HLSI 201210R47 300 nH 470 nH 520 nH CIN 2.2 F, 6.3 V, X5R, 0402 Murata or Equivalent GRM155R60J225ME15 GRM188R60J225KE19D 1.0 F 2.2 F COUT 4.7 F, X5R, 0402 Murata or Equivalent GRM155R60G475M GRM155R60E475ME760 1.6 F 4.7 F |
类似零件编号 - FAN53601 |
|
类似说明 - FAN53601 |
|
|
链接网址 |
隐私政策 |
ALLDATASHEETCN.COM |
ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 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 |