 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LM2595 Datasheet(PDF) 9 Page - National Semiconductor (TI) |
|
|
|
|||||||||||||||||||||||||||||
LM2595 Datasheet(HTML) 9 Page - National Semiconductor (TI) |
|
|
9 / 29 page  LM2595 Series Buck Regulator Design Procedure (Fixed Output) PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) Given: V OUT = Regulated Output Voltage (3.3V, 5V or 12V) V IN(max) = Maximum DC Input Voltage I LOAD(max) = Maximum Load Current Given: V OUT = 5V V IN(max) = 12V I LOAD(max) = 1A 1. Inductor Selection (L1) A. Select the correct inductor value selection guide from Fig- ure 4 , Figure 5,or Figure 6. (Output voltages of 3.3V, 5V, or 12V respectively.) For all other voltages, see the design pro- cedure for the adjustable version. B. From the inductor value selection guide, identify the induc- tance region intersected by the Maximum Input Voltage line and the Maximum Load Current line. Each region is identified by an inductance value and an inductor code (LXX). C. Select an appropriate inductor from the four manufactur- er’s part numbers listed in Figure 8. 1. Inductor Selection (L1) A. Use the inductor selection guide for the 5V version shown in Figure 5. B. From the inductor value selection guide shown in Figure 5, the inductance region intersected by the 12V horizontal line and the 1A vertical line is 68 µH, and the inductor code is L30. C. The inductance value required is 68 µH. From the table in Figure 8, go to the L30 line and choose an inductor part num- ber from any of the four manufacturers shown. (In most in- stance, both through hole and surface mount inductors are available.) 2. Output Capacitor Selection (C OUT) A. In the majority of applications, low ESR (Equivalent Series Resistance) electrolytic capacitors between 47 µF and 330 µF and low ESR solid tantalum capacitors between 56 µF and 270 µF provide the best results. This capacitor should be located close to the IC using short capacitor leads and short copper traces. Do not use capacitors larger than 330 µF. For additional information, see section on output capaci- tors in application information section. B. To simplify the capacitor selection procedure, refer to the quick design component selection table shown in Figure 2. This table contains different input voltages, output voltages, and load currents, and lists various inductors and output ca- pacitors that will provide the best design solutions. C. The capacitor voltage rating for electrolytic capacitors should be at least 1.5 times greater than the output voltage, and often much higher voltage ratings are needed to satisfy the low ESR requirements for low output ripple voltage. D. For computer aided design software, see Switchers Made Simple® version 4.2 or later. 2. Output Capacitor Selection (C OUT) A. See section on output capacitors in application infor- mation section. B. From the quick design component selection table shown in Figure 2, locate the 5V output voltage section. In the load current column, choose the load current line that is closest to the current needed in your application, for this example, use the 1A line. In the maximum input voltage column, select the line that covers the input voltage needed in your application, in this example, use the 15V line. Continuing on this line are recommended inductors and capacitors that will provide the best overall performance. The capacitor list contains both through hole electrolytic and surface mount tantalum capacitors from four different capaci- tor manufacturers. It is recommended that both the manufac- turers and the manufacturer’s series that are listed in the table be used. In this example aluminum electrolytic capacitors from several different manufacturers are available with the range of ESR numbers needed. 220 µF 25V Panasonic HFQ Series 220 µF 25V Nichicon PL Series C. For a 5V output, a capacitor voltage rating at least 7.5V or more is needed. But, in this example, even a low ESR, switching grade, 220 µF 10V aluminum electrolytic capacitor would exhibit approximately 225 m Ω of ESR (see the curve in Figure 14 for the ESR vs voltage rating). This amount of ESR would result in relatively high output ripple voltage. To reduce the ripple to 1% of the output voltage, or less, a ca- pacitor with a higher voltage rating (lower ESR) should be se- lected. A 16V or 25V capacitor will reduce the ripple voltage by approximately half. Procedure continued on next page. Example continued on next page. www.national.com 9 |
Similar Part No. - LM2595 |
|
Similar Description - LM2595 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
