This design eliminates the need to etch a circuit board for the small surface mount chip. Peripheral components are large "through hole" items soldered together on a blank board.
Results for Max 1674 are similar.
| i, amps
(two white leds in parallel) |
dV, volts, across
R=.333 ohms |
dV led, volts |
| 0 | 0 | 2.40 |
| .010 | .0033 | 3.09 |
| .020 | .0066 | 3.25 |
| .050 | .0167 | 3.55 |
| i, amps
(1 watt Luxeon Star) |
dV across
R=.333 ohms |
Vled |
| 0 | 0 | 2.40 |
| .100 | .033 | 2.87 |
| .200 | .066 | 2.99 |
| .275 | .092 | 3.08 |
| .300 | .100 | 3.10 |
| .325 | .108 | 3.12 |
| .350 | .117 | 3.14 |
note: R is three 1 ohm resistors in parallel.
1/R = (1/1) + (1/1) + (1/1) = 3, so R = .333 ohms
Output Voltage IC Operating Temperature, Degrees C Degrees F 2.58 38 100 2.94 46 114 3.11 54 129 From Max1797 and Max 1674 data sheet:
Ambient temperature range is -40 C to 85 C, with a maximum junction temperature of 150 C
Efficiency:dVin = .185 volts = I R
I = dV/R = .185/.333 = .555 amps
V bat (2C nimh) under load = 2.34 volts after going through R = .333 ohms
Vout to led under load = 3.15 volts, I led = .365 amps (extrapolated from data above)
P = V I
Pout/Pin = (3.15)(.365)/(2.34)(.555) = .885