Electronic Components Datasheet Search |
|
LT3506 Datasheet(PDF) 9 Page - Linear Technology |
|
LT3506 Datasheet(HTML) 9 Page - Linear Technology |
9 / 24 page LT3506/LT3506A 3506afb The current in the inductor is a triangle wave with an average value equal to the load current. The peak switch current is equal to the output current plus half the peak-to- peak inductor ripple current. The LT3506 limits its switch current in order to protect itself and the system from overload faults. Therefore, the maximum output current that the LT3506 will deliver depends on the current limit, the inductor value and the input and output voltages. L is chosen based on output current requirements, output voltageripplerequirements,sizerestrictionsandefficiency goals. When the switch is off, the inductor sees the output voltage plus the catch diode drop. This gives the peak-to- peak ripple current in the inductor: ΔIL = (1 – DC)(VOUT + VD)/(L • f) where f is the switching frequency of the LT3506 and L is the value of the inductor. The peak inductor and switch current is ISWPK = ILPK = IOUT + ΔIL/2. To maintain output regulation, this peak current must be less than the LT3506’s switch current limit ILIM. ILIM is at least 2A at low duty cycle and decreases linearly to 1.7A at DC = 0.8. The maximum output current is a function of the chosen inductor value: IOUT(MAX) = ILIM – ΔIL/2 = 2A • (1 – 0.21 • DC) – ΔIL/2 If the inductor value is chosen so that the ripple current is small, then the available output current will be near the switch current limit. One approach to choosing the inductor is to start with the simple rule given above, look at the available inductors, and choose one to meet cost or space goals. Then use these equations to check that the LT3506 will be able to deliver the required output current. Note again that these equations assume that the inductor current is continuous. Discontinuous operation occurs when IOUT is less than ΔIL/2 as calculated above. Table 1. Inductors Part Number Value (μH) ISAT (A) DCR ( W) Height (mm) Sumida CR43-3R3 3.3 1.44 0.086 3.5 CR43-4R7 4.7 1.15 0.109 3.5 CDC5d23-2R2 2.2 2.16 0.030 2.5 CDRH5D28-2R6 2.6 2.60 0.013 3.0 CDRH6D26-5R6 5.6 2.00 0.027 2.8 CDH113-100 10 2.00 0.047 3.7 Coilcraft DO1606T-152 1.5 2.10 0.060 2.0 DO1606T-222 2.2 1.70 0.070 2.0 DO1608C-332 3.3 2.00 0.080 2.9 DO1608C-472 4.7 1.50 0.090 2.9 DO1813P-682HC 6.8 2.20 0.080 5.0 Cooper SD414-2R2 2.2 2.73 0.061 1.35 SD414-6R8 6.8 1.64 0.135 1.35 UP1B-100 10 1.90 0.111 5.0 Toko (D62F)847FY-2R4M 2.4 2.5 0.037 2.7 (D73LF)817FY- 2R2M 2.2 2.7 0.03 3.0 Input Capacitor Selection Bypass the input of the LT3506 circuit with a 4.7μF or higher ceramic capacitor of X7R or X5R type. A lower value or a less expensive Y5V type can be used if there is additional bypassing provided by bulk electrolytic or tan- talum capacitors. The following paragraphs describe the input capacitor considerations in more detail. Step-down regulators draw current from the input supply in pulses with very fast rise and fall times. The input capacitor is requiredtoreducetheresultingvoltagerippleattheLT3506 and to force this very high frequency switching current into a tight local loop, minimizing EMI. The input capaci- APPLICATIO S I FOR ATIO |
Similar Part No. - LT3506 |
|
Similar Description - LT3506 |
|
|
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 |