Subversion Repositories OpenARM Single-board Computer

Manufacturer: STMICROELECTRONICS
Order Code: 1202824
Manufacturer Part No: LD1117STR-E
V REG ADJ +1.25/15V, SMD, 1117

http://uk.farnell.com/1202824/semiconductors-integrated-circuits/product.us0?sku=stmicroelectronics-ld1117str-e
http://www.st.com/stonline/products/literature/ds/2572/ld1117xx.pdf

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 = 240
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 Limmits ==

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)

== +3.3V Limmits ==

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)