Electronic Components Datasheet Search |
|
NPO5DB4R7M Datasheet(PDF) 10 Page - Advanced Analogic Technologies |
|
NPO5DB4R7M Datasheet(HTML) 10 Page - Advanced Analogic Technologies |
10 / 14 page AAT1157 1MHz 1.2A Buck DC/DC Converter 10 1157.2005.11.1.4 Where I Q is the AAT1157 quiescent current. Once the total losses have been determined, the junction temperature can be derived from the θ JA for the QFN package. Close attention should be paid to the proper layout for the QFN package. Proper size and placement of thermal routing vias below the central paddle is necessary for good heat transfer to other PCB layers and their ground planes. The θ JA for the QFN package with no connection to the cen- tral paddle is 50°C/W. The actual θ JA will vary with the number and type of vias. The PCB board size, number of board layers, and ground plane charac- teristics also influence the θ JA. A good thermal con- nection from the paddle to the PCB ground plane layers can significantly reduce θ JA. Adjustable Output Resistors R3 and R4, as shown in Figure 1, force the output to regulate higher than the 0.6V refer- ence voltage level. The optimum value for R4 is 59k Ω. Values higher than this can cause stability problems, while lower values can degrade light load efficiency. For a 2.5V output with R4 set to 59k Ω, R3 is 187kΩ. Table 1: Suggested Component Values. Buck-Boost Output Figure 4 shows how to configure the AAT1157 in a buck boost configuration with an external MOSFET and Schottky diode. The converter has a 3.3V 600mA output with an input voltage ranging from 2.7V to 5.5V. Output Output R3 for Voltage L1 Capacitor R4 = 59k Ω Ω (V) (µH) (C3-C4) (µF) (k Ω Ω) 0.8 1.5 - 2.6 3x 22 19.6 1.0 1.5 - 3.3 2x 22 39.2 1.2 2.2 - 3.3 2x 22 59 1.5 2.2 - 4.7 2x 22 88.7 1.8 3.0 - 4.7 2x 22 118 2.5 3.0 - 4.7 2x 22 187 3.3 2.2 - 4.7 22 267 ⎛⎞ ⎝⎠ R3 = -1 · R4 = - 1 · 59k Ω = 187kΩ V O V REF ⎛⎞ ⎝⎠ 2.5V 0.6V T J = P · Θ JA + TAMB I O 2 ⋅ (R DSON(HS) ⋅ V O + RDSON(LS) ⋅ (V IN - VO)) P = V IN + (t sw ⋅ F ⋅ I O ⋅ V IN + IQ) ⋅ V IN Figure 4: AAT1157 Buck Boost Converter. 3.0 µH L1 22 µF C1 100 R1 0.1 µF C2 C1 Murata 22 µF 10V X7R 1210 GRM32ER71A226KE20L C3,C4 MuRata 22 µF 6.3V X5R 0805 GRM21BR60J226ME39L L1 Sumida CDRH5D28-3R0 LX 14 N/C 6 EN 7 VCC 9 VP 10 N/C 8 LX 13 PGND PGND PGND 3 VP 12 VP 11 OUT 4 LX 15 2 1 SGND 5 N/C 16 AAT1157 U1 267k R2 59.0k R3 Si2302ADS Q1 MBRM120L D1 2x 22 µF C3,C4 VIN 2.7V to 5.5V VO 3.3V/600mA |
Similar Part No. - NPO5DB4R7M |
|
Similar Description - NPO5DB4R7M |
|
|
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 |