 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LTC1149 Datasheet(PDF) 7 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LTC1149 Datasheet(HTML) 7 Page - Linear Technology |
|
|
7 / 20 page  7 LTC1149 LTC1149-3.3/LTC1149-5 TEST CIRCUIT APPLICATIO S I FOR ATIO Typical Application Circuit The basic LTC1149 series application circuit is shown in Figure 1. External component selection is driven by the input voltage and output load requirement, and begins with the selection of RSENSE. Once RSENSE is known, CT and L can be chosen. Next, the power MOSFETs and D1 are selected. Finally, CIN and COUT are selected and the loop is compensated. The circuit shown in Figure 1 can be configured for operation up to an input voltage of 48V. If the application does not require greater than 15V opera- tion, then the LTC1148 should be used. RSENSE Selection for Output Current RSENSE is chosen based on the required output current. The LTC1149 series current comparator has a threshold range which extends from a minimum of 25mV/RSENSE to a maximum of 150mV/RSENSE. The current comparator threshold sets the peak of the inductor ripple current, yielding a maximum output current IMAX equal to the peak value less half the peak-to-peak ripple current. For proper Burst Mode operation, IRIPPLE(P-P) must be less than or equal to the minimum current comparator threshold. Since efficiency generally increases with ripple current, the maximum allowable ripple current is assumed, i.e., IRIPPLE(P-P) = 25mV/RSENSE (see CT and L Selection for Operating Frequency). Solving for RSENSE and allowing a margin for variations in the LTC1149 series and external component values yields: RSENSE = 100mV IMAX A graph for selecting RSENSE versus maximum output current is given in Figure 2. The LTC1149 series works well with values of RSENSE from 0.02Ω to 0.2Ω. The load current below which Burst Mode operation commences, IBURST, and the peak short-circuit current, ISC(PK), both track IMAX. Once RSENSE has been chosen, IBURST and ISC(PK) can be predicted from the following equations: IBURST ≈ 15mV RSENSE ISC(PK) = 150mV RSENSE + PGATE VIN VCC PDRIVE VCC CT ITH SENSE– CAP SHDN2 RGND NGATE PGND SGND SENSE+ 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 LTC1149 0.047 µF 1 µF 0.068 µF VIN 0.1 µF + V8 3300pF 390pF 1000pF + V9 – V8 25k 75k 220 µF 0.05 Ω + V10 VOUT + V15 50 µH IRF9Z34 220 µF 100V IRFZ34 MBR380 1149 TC VFB/ SHDN1 1k + + |
Similar Part No. - LTC1149 |
|
Similar Description - LTC1149 |
|
|
|
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
