Rev 97 | Rev 106 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 88 | jelle | 1 | Manufacturer: STMICROELECTRONICS |
| 2 | Order Code: 1202824 |
||
| 3 | Manufacturer Part No: LD1117STR-E |
||
| 4 | V REG ADJ +1.25/15V, SMD, 1117 |
||
| 5 | |||
| 6 | http://uk.farnell.com/1202824/semiconductors-integrated-circuits/product.us0?sku=stmicroelectronics-ld1117str-e |
||
| 7 | http://www.st.com/stonline/products/literature/ds/2572/ld1117xx.pdf |
||
| 8 | |||
| 9 | VOUT = VREF (1 + R2 / R1) |
||
| 10 | |||
| 11 | VREF = 1.25V |
||
| 12 | |||
| 13 | # notes |
||
| 14 | |||
| 15 | The power dissipated by the device will be equal to: |
||
| 16 | IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) |
||
| 17 | where, |
||
| 18 | IOUT(MAX) = 250mA |
||
| 19 | VIN(MAX) = 6V |
||
| 20 | IGND at (IOUT = 250mA, VIN = 6V) = 5mA |
||
| 21 | So, |
||
| 22 | P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W |
||
| 23 | |||
| 24 | page 7: Thermal resistance junction-case: 14 C/W |
||
| 25 | |||
| 26 | |||
| 27 | === 3.0 V ==== |
||
| 28 | |||
| 29 | R1 = 240 |
||
| 30 | R2 = 330 |
||
| 31 | |||
| 32 | VOUT = VREF (1 + R2 / R1) |
||
| 33 | 3.000 = 1.25 * (1 + 280 / 200) |
||
| 97 | jelle | 34 | 2.969 = 1.25 * (1 + 330 / 240) |
| 88 | jelle | 35 | 3.125 = 1.25 * (1 + 330 / 220) |
| 36 | |||
| 37 | ( (VOUT / VREF) -1 ) = (R2 / R1) |
||
| 38 | |||
| 39 | I = U / R |
||
| 40 | 3 / 200 = 0.015 |
||
| 41 | |||
| 42 | P = I * U |
||
| 43 | |||
| 44 | 0.015 * 3 = 0.045 W |
||
| 45 | 0603 Case Size = 0.063 W |
||
| 46 | |||
| 47 | |||
| 48 | === 3.3 V === |
||
| 49 | |||
| 50 | R1 = 240 |
||
| 51 | R2 = 390 |
||
| 52 | |||
| 53 | VOUT = VREF (1 + R2 / R1) |
||
| 54 | 3.281 = 1.25 * (1 + 390 / 240) |
||
| 97 | jelle | 55 | |
| 100 | jelle | 56 | == +3.0V Limits == |
| 97 | jelle | 57 | |
| 58 | VOUT = VREF (1 + R2 / R1) |
||
| 59 | R1 = 240 |
||
| 60 | R2 = 330 |
||
| 61 | R1 = 99% = 237.6 |
||
| 62 | R1 = 101% = 242.4 |
||
| 63 | R2 = 99% = 326.7 |
||
| 64 | R2 = 101% = 333.3 |
||
| 65 | |||
| 66 | MIN(2.940) = 1.238 * (1 + 326.7 / 237.6) |
||
| 67 | TYP(2.969) = 1.250 * (1 + 330.0 / 240.0) |
||
| 68 | MAX(3.004) = 1.262 * (1 + 333.3 / 242.4) |
||
| 69 | |||
| 100 | jelle | 70 | == +3.125 V Limits == |
| 97 | jelle | 71 | |
| 72 | VOUT = VREF (1 + R2 / R1) |
||
| 100 | jelle | 73 | R1 = 220 |
| 74 | R2 = 330 |
||
| 75 | R1 = 99% = 217.8 |
||
| 76 | R1 = 101% = 222.2 |
||
| 77 | R2 = 99% = 326.7 |
||
| 78 | R2 = 101% = 333.3 |
||
| 79 | |||
| 80 | MIN(3.095) = 1.238 * (1 + 326.7 / 217.8) |
||
| 81 | TYP(3.125) = 1.250 * (1 + 330.0 / 220.0) |
||
| 82 | MAX(3.115) = 1.262 * (1 + 333.3 / 222.2) |
||
| 83 | |||
| 84 | 3.125 = 1.25 * (1 + 330 / 220) |
||
| 85 | |||
| 86 | |||
| 87 | == +3.3V Limits == |
||
| 88 | |||
| 89 | VOUT = VREF (1 + R2 / R1) |
||
| 97 | jelle | 90 | R1 = 240 |
| 91 | R2 = 390 |
||
| 92 | R1 = 99% = 237.6 |
||
| 93 | R1 = 101% = 242.4 |
||
| 94 | R2 = 99% = 386.1 |
||
| 95 | R2 = 101% = 393.9 |
||
| 96 | MIN(3.250) = 1.238 * (1 + 386.1 / 237.6) |
||
| 97 | TYP(3.281) = 1.238 * (1 + 386.1 / 237.6) |
||
| 98 | MAX(3.313) = 1.262 * (1 + 393.9 / 242.4) |