 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LT3479EDE Datasheet(PDF) 9 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LT3479EDE Datasheet(HTML) 9 Page - Linear Technology |
|
|
9 / 20 page  LT3479 9 3479fb Setting Negative Output Voltages To set a negative output voltage, select the values of R3 and R4 (see Figure 3) according to the following equation: VV R R OUT = ⎛ ⎝⎜ ⎞ ⎠⎟ –. 1 235 3 4 Figure 2. Positive Output Voltage Feedback Connections R2 R1 3479 F02 FBN VREF VOUT LT3479 FBP Figure 3. Negative Output Voltage Feedback Connections R4 R3 3479 F03 FBP VREF –VOUT LT3479 FBN APPLICATIONS INFORMATION Diode Selection Schottky diodes, with their low forward voltage drop and fast switching speed, are ideal for LT3479 applications. Table 3 lists several Schottky diodes that work well with the LT3479. The diode’s average current rating must exceed the average output current. The diode’s maximum reverse voltage must exceed the output voltage. The diode conducts current only when the power switch is turned off (typically less than 50% duty cycle), so a 3A diode is sufficient for most designs. The companies below also offer Schottky diodes with high voltage and current ratings. Table 3. Suggested Diodes MANUFACTURER PART NUMBER MAX CURRENT (A) MAX REVERSE VOLTAGE (V) MANUFACTURER UPS340 UPS315 3 3 40 15 Microsemi www.microsemi.com B220 B230 B240 B320 B330 B340 SBM340 2 2 2 3 3 3 3 20 30 40 20 30 40 40 Diodes, Inc www.diodes.com Setting Positive Output Voltages To set a positive output voltage, select the values of R1 and R2 (see Figure 2) according to the following equation: VV R R OUT =+ ⎛ ⎝⎜ ⎞ ⎠⎟ 1 235 1 1 2 . Board Layout As with all switching regulators, careful attention must be paid to the PCB board layout and component place- ment. To maximize efficiency, switch rise and fall times are made as short as possible. To prevent radiation and high frequency resonance problems, proper layout of the high frequency switching path is essential. Minimize the length and area of all traces connected to the SW pin and always use a ground plane under the switching regulator to minimize interplane coupling. The signal path including the switch, output diode D1 and output capacitor COUT, contains nanosecond rise and fall times and should be kept as short as possible. Recommended component placement is shown in Figure 4. Soft-Start For many applications, it is necessary to minimize the inrush current at start-up. The built-in soft-start circuit significantly reduces the start-up current spike and output voltage overshoot. A typical value is 10nF for 1.65ms. Figure 5 shows the start-up output voltage and induc- tor current waveforms in a typical application without a soft-start capacitor. Notice the output voltage overshoot and the large initial current. The addition of a 22nF capaci- tor eliminates the output overshoot and reduces the peak inductor current (Figure 6). |
Similar Part No. - LT3479EDE |
|
Similar Description - LT3479EDE |
|
|
|
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
