Manufacturer: STMICROELECTRONICS Order Code: 1202824 Manufacturer Part No: LD1117STR-E Description: V REG ADJ +1.25/15V, SMD, 1117 Supplier: http://nl.farnell.com/stmicroelectronics/ld1117str-e/v-reg-adj-1-25-15v-smd-1117/dp/1202824 Datasheet: http://www.st.com/stonline/products/literature/ds/2572/ld1117xx.pdf Datasheet: http://www.st.com/stonline/books/pdf/docs/2572.pdf Catalogue Page: 545 / EBU Price: € 1,32 ------------------------------------------------------------------------ page 28 of datasheet Case Style: SOT-223 SOT-223 SOT23 & SOT223 Packages (Example: SOT230P700X180-4) SOT + Pitch P + Lead Span Nominal X Height - Pin Qty SOT230P530X700-4__ST_LD1117SXX_SOT223 footprint looks ok, bit oversized pads, checked the part on printed paper i recommend a new footprint for this device ------------------------------------------------------------------------ ;VOUT = VREF (1 + R2 / R1) ; ;VREF = 1.25V ; ;# notes ; ;The power dissipated by the device will be equal to: ; IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) ;where, ; IOUT(MAX) = 250mA ; VIN(MAX) = 6V ; IGND at (IOUT = 250mA, VIN = 6V) = 5mA ;So, ; P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W ; ;page 7: Thermal resistance junction-case: 14 C/W ; ; ;=== 3.0 V ==== ; ;R1 = 220 ;R2 = 330 ; ;VOUT = VREF (1 + R2 / R1) ;3.000 = 1.25 * (1 + 280 / 200) ;2.969 = 1.25 * (1 + 330 / 240) ;3.125 = 1.25 * (1 + 330 / 220) ; ;( (VOUT / VREF) -1 ) = (R2 / R1) ; ;I = U / R ;3 / 200 = 0.015 ; ;P = I * U ; ;0.015 * 3 = 0.045 W ;0603 Case Size = 0.063 W ; ; ;=== 3.3 V === ; ;R1 = 240 ;R2 = 390 ; ;VOUT = VREF (1 + R2 / R1) ;3.281 = 1.25 * (1 + 390 / 240) ; ;== +3.0V Limits == ; ;VOUT = VREF (1 + R2 / R1) ;R1 = 240 ;R2 = 330 ;R1 = 99% = 237.6 ;R1 = 101% = 242.4 ;R2 = 99% = 326.7 ;R2 = 101% = 333.3 ; ;MIN(2.940) = 1.238 * (1 + 326.7 / 237.6) ;TYP(2.969) = 1.250 * (1 + 330.0 / 240.0) ;MAX(3.004) = 1.262 * (1 + 333.3 / 242.4) ; ;== +3.125 V Limits == ; ;VOUT = VREF (1 + R2 / R1) ;R1 = 220 ;R2 = 330 ;R1 = 99% = 217.8 ;R1 = 101% = 222.2 ;R2 = 99% = 326.7 ;R2 = 101% = 333.3 ; ;MIN(3.095) = 1.238 * (1 + 326.7 / 217.8) ;TYP(3.125) = 1.250 * (1 + 330.0 / 220.0) ;MAX(3.115) = 1.262 * (1 + 333.3 / 222.2) ; ;3.125 = 1.25 * (1 + 330 / 220) ; ; ;== +3.3V Limits == ; ;VOUT = VREF (1 + R2 / R1) ;R1 = 240 ;R2 = 390 ;R1 = 99% = 237.6 ;R1 = 101% = 242.4 ;R2 = 99% = 386.1 ;R2 = 101% = 393.9 ;MIN(3.250) = 1.238 * (1 + 386.1 / 237.6) ;TYP(3.281) = 1.238 * (1 + 386.1 / 237.6) ;MAX(3.313) = 1.262 * (1 + 393.9 / 242.4)