 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LTC3407AEMSE-PBF Datasheet(PDF) 8 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LTC3407AEMSE-PBF Datasheet(HTML) 8 Page - Linear Technology |
|
|
8 / 16 page  LTC3407A 8 3407afa Inductor Selection Although the inductor does not influence the operat- ing frequency, the inductor value has a direct effect on ripple current. The inductor ripple current ΔIL decreases with higher inductance and increases with higher VIN or VOUT: IL = VOUT fO •L •1– VOUT VIN Accepting larger values of ΔIL allows the use of low inductances, but results in higher output voltage ripple, greater core losses, and lower output current capability. A reasonable starting point for setting ripple current is ΔIL = 0.3 • ILIM, where ILIM is the peak switch current limit. The largest ripple current ΔIL occurs at the maximum input voltage. To guarantee that the ripple current stays below a specified maximum, the inductor value should be chosen according to the following equation: L = VOUT fO • IL •1– VOUT VIN(MAX) The inductor value will also have an effect on Burst Mode operation. The transition from low current operation begins when the peak inductor current falls below a level set by the burst clamp. Lower inductor values result in higher ripple current which causes this transition to occur at lower load currents. This causes a dip in efficiency in the upper range of low current operation. In Burst Mode operation, lower inductance values will cause the burst frequency to increase. Inductor Core Selection Different core materials and shapes will change the size/ current and price/current relationship of an inductor. Toroid or shielded pot cores in ferrite or permalloy materials are small and don’t radiate much energy, but generally cost more than powdered iron core inductors with similar elec- trical characterisitics. The choice of which style inductor to use often depends more on the price vs size require- ments and any radiated field/EMI requirements than on what the LTC3407A requires to operate. Table 1 shows some typical surface mount inductors that work well in LTC3407A applications. Table 1. Representative Surface Mount Inductors MANUF- ACTURER PART NUMBER VALUE MAX DC CURRENT DCR HEIGHT Taiyo Yuden CB2016T2R2M CB2012T2R2M CB2016T3R3M 2.2μH 2.2μH 3.3μH 510mA 530mA 410mA 0.13Ω 0.33Ω 0.27Ω 1.6mm 1.25mm 1.6mm Panasonic ELT5KT4R7M 4.7μH 950mA 0.2Ω 1.2mm Sumida CDRH2D18/LD 4.7μH 630mA 0.086Ω 2mm Murata LQH32CN4R7M23 4.7μH 450mA 0.2Ω 2mm Taiyo Yuden NR30102R2M NR30104R7M 2.2μH 4.7μH 1100mA 750mA 0.1Ω 0.19Ω 1mm 1mm FDK FDKMIPF2520D FDKMIPF2520D FDKMIPF2520D 4.7μH 3.3μH 2.2μH 1100mA 1200mA 1300mA 0.11Ω 0.1Ω 0.08Ω 1mm 1mm 1mm TDK VLF3010AT4R7- MR70 VLF3010AT3R3- MR87 VLF3010AT2R2- M1R0 4.7μH 3.3μH 2.2μH 700mA 870mA 1000mA 0.28Ω 0.17Ω 0.12Ω 1mm 1mm 1mm Input Capacitor (CIN) Selection In continuous mode, the input current of the converter is a square wave with a duty cycle of approximately VOUT/VIN. To prevent large voltage transients, a low equivalent series resistance (ESR) input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: IRMS ≈IMAX VOUT(VIN –VOUT) VIN where the maximum average output current IMAX equals the peak current minus half the peak-to-peak ripple cur- rent, IMAX = ILIM – ΔIL/2. APPLICATIONS INFORMATION Figure 1. LTC3407A General Schematic VOUT2 RUN/SS2 VIN VIN = 2.5V TO 5.5V VOUT1 RUN/SS1 POR SW1 VFB1 GND VFB2 SW2 MODE/SYNC LTC3407A CIN R7 POWER-ON RESET C1 C2 L1 L2 R4 R2 R1 R3 COUT2 C4 C3 COUT1 3407A F01 PULSESKIP* BURST* *MODE/SYNC = 0V: PULSE SKIP MODE/SYNC = VIN: Burst Mode R6 R5 |
Similar Part No. - LTC3407AEMSE-PBF |
|
Similar Description - LTC3407AEMSE-PBF |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.NET |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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
