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Rev | Author | Line No. | Line |
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88 | jelle | 1 | Manufacturer: STMICROELECTRONICS |
2 | Order Code: 1202824 |
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3 | Manufacturer Part No: LD1117STR-E |
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257 | jelle | 4 | Description: V REG ADJ +1.25/15V, SMD, 1117 |
5 | Supplier: http://uk.farnell.com/1202824/semiconductors-integrated-circuits/product.us0?sku=stmicroelectronics-ld1117str-e |
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6 | Datasheet: http://www.st.com/stonline/products/literature/ds/2572/ld1117xx.pdf |
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7 | Catalogue Page: 436 / EBU |
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88 | jelle | 8 | |
257 | jelle | 9 | ------------------------------------------------------------------------ |
88 | jelle | 10 | |
11 | VOUT = VREF (1 + R2 / R1) |
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12 | |||
13 | VREF = 1.25V |
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14 | |||
15 | # notes |
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16 | |||
17 | The power dissipated by the device will be equal to: |
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18 | IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) |
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19 | where, |
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20 | IOUT(MAX) = 250mA |
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21 | VIN(MAX) = 6V |
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22 | IGND at (IOUT = 250mA, VIN = 6V) = 5mA |
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23 | So, |
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24 | P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W |
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25 | |||
26 | page 7: Thermal resistance junction-case: 14 C/W |
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27 | |||
28 | |||
29 | === 3.0 V ==== |
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30 | |||
106 | jelle | 31 | R1 = 220 |
88 | jelle | 32 | R2 = 330 |
33 | |||
34 | VOUT = VREF (1 + R2 / R1) |
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35 | 3.000 = 1.25 * (1 + 280 / 200) |
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97 | jelle | 36 | 2.969 = 1.25 * (1 + 330 / 240) |
88 | jelle | 37 | 3.125 = 1.25 * (1 + 330 / 220) |
38 | |||
39 | ( (VOUT / VREF) -1 ) = (R2 / R1) |
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40 | |||
41 | I = U / R |
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42 | 3 / 200 = 0.015 |
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43 | |||
44 | P = I * U |
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45 | |||
46 | 0.015 * 3 = 0.045 W |
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47 | 0603 Case Size = 0.063 W |
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48 | |||
49 | |||
50 | === 3.3 V === |
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51 | |||
52 | R1 = 240 |
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53 | R2 = 390 |
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54 | |||
55 | VOUT = VREF (1 + R2 / R1) |
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56 | 3.281 = 1.25 * (1 + 390 / 240) |
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97 | jelle | 57 | |
100 | jelle | 58 | == +3.0V Limits == |
97 | jelle | 59 | |
60 | VOUT = VREF (1 + R2 / R1) |
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61 | R1 = 240 |
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62 | R2 = 330 |
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63 | R1 = 99% = 237.6 |
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64 | R1 = 101% = 242.4 |
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65 | R2 = 99% = 326.7 |
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66 | R2 = 101% = 333.3 |
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67 | |||
68 | MIN(2.940) = 1.238 * (1 + 326.7 / 237.6) |
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69 | TYP(2.969) = 1.250 * (1 + 330.0 / 240.0) |
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70 | MAX(3.004) = 1.262 * (1 + 333.3 / 242.4) |
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71 | |||
100 | jelle | 72 | == +3.125 V Limits == |
97 | jelle | 73 | |
74 | VOUT = VREF (1 + R2 / R1) |
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100 | jelle | 75 | R1 = 220 |
76 | R2 = 330 |
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77 | R1 = 99% = 217.8 |
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78 | R1 = 101% = 222.2 |
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79 | R2 = 99% = 326.7 |
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80 | R2 = 101% = 333.3 |
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81 | |||
82 | MIN(3.095) = 1.238 * (1 + 326.7 / 217.8) |
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83 | TYP(3.125) = 1.250 * (1 + 330.0 / 220.0) |
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84 | MAX(3.115) = 1.262 * (1 + 333.3 / 222.2) |
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85 | |||
86 | 3.125 = 1.25 * (1 + 330 / 220) |
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87 | |||
88 | |||
89 | == +3.3V Limits == |
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90 | |||
91 | VOUT = VREF (1 + R2 / R1) |
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97 | jelle | 92 | R1 = 240 |
93 | R2 = 390 |
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94 | R1 = 99% = 237.6 |
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95 | R1 = 101% = 242.4 |
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96 | R2 = 99% = 386.1 |
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97 | R2 = 101% = 393.9 |
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98 | MIN(3.250) = 1.238 * (1 + 386.1 / 237.6) |
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99 | TYP(3.281) = 1.238 * (1 + 386.1 / 237.6) |
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100 | MAX(3.313) = 1.262 * (1 + 393.9 / 242.4) |