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88 jelle 1
Manufacturer: STMICROELECTRONICS
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Order Code: 1202824
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Manufacturer Part No: LD1117STR-E
257 jelle 4
Description: V REG ADJ +1.25/15V, SMD, 1117
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Supplier: http://uk.farnell.com/1202824/semiconductors-integrated-circuits/product.us0?sku=stmicroelectronics-ld1117str-e
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Datasheet: http://www.st.com/stonline/products/literature/ds/2572/ld1117xx.pdf
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Catalogue Page: 436 / EBU
88 jelle 8
 
257 jelle 9
------------------------------------------------------------------------
88 jelle 10
 
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VOUT = VREF (1 + R2 / R1)
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VREF = 1.25V
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# notes
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The power dissipated by the device will be equal to:
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  IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX))
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where,
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  IOUT(MAX) = 250mA
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  VIN(MAX) = 6V
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  IGND at (IOUT = 250mA, VIN = 6V) = 5mA
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So,
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  P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W
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page 7: Thermal resistance junction-case: 14 C/W
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=== 3.0 V ====
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106 jelle 31
R1 = 220
88 jelle 32
R2 = 330
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VOUT = VREF (1 + R2 / R1)
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3.000 = 1.25 * (1 + 280 / 200)
97 jelle 36
2.969 = 1.25 * (1 + 330 / 240)
88 jelle 37
3.125 = 1.25 * (1 + 330 / 220)
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( (VOUT / VREF) -1 ) = (R2 / R1)
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I = U / R
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3 / 200 = 0.015
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P = I * U
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0.015 * 3 = 0.045 W
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0603 Case Size = 0.063 W
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=== 3.3 V ===
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R1 = 240
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R2 = 390
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VOUT = VREF (1 + R2 / R1)
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3.281 = 1.25 * (1 + 390 / 240)
97 jelle 57
 
100 jelle 58
== +3.0V Limits ==
97 jelle 59
 
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VOUT = VREF (1 + R2 / R1)
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R1 = 240
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R2 = 330
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R1 =  99% = 237.6
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R1 = 101% = 242.4
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R2 =  99% = 326.7
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R2 = 101% = 333.3
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MIN(2.940) = 1.238 * (1 + 326.7 / 237.6)
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TYP(2.969) = 1.250 * (1 + 330.0 / 240.0)
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MAX(3.004) = 1.262 * (1 + 333.3 / 242.4)
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100 jelle 72
== +3.125 V Limits ==
97 jelle 73
 
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VOUT = VREF (1 + R2 / R1)
100 jelle 75
R1 = 220
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R2 = 330
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R1 =  99% = 217.8
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R1 = 101% = 222.2
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R2 =  99% = 326.7
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R2 = 101% = 333.3
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MIN(3.095) = 1.238 * (1 + 326.7 / 217.8)
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TYP(3.125) = 1.250 * (1 + 330.0 / 220.0)
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MAX(3.115) = 1.262 * (1 + 333.3 / 222.2)
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3.125 = 1.25 * (1 + 330 / 220)
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88
 
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== +3.3V Limits ==
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VOUT = VREF (1 + R2 / R1)
97 jelle 92
R1 = 240
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R2 = 390
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R1 =  99% = 237.6
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R1 = 101% = 242.4
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R2 =  99% = 386.1
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R2 = 101% = 393.9
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MIN(3.250) = 1.238 * (1 + 386.1 / 237.6)
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TYP(3.281) = 1.238 * (1 + 386.1 / 237.6)
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MAX(3.313) = 1.262 * (1 + 393.9 / 242.4)