johnnybgood
Newly Enlightened
- Joined
- Sep 6, 2010
- Messages
- 4
Hi All. I'm really new to this, so please be gentle! I spent a few hours looking through this forum, but so far haven't found answers to exactly what I'm looking for.
Goal:
- I want to be able to hook up a battery cell (or cells) to a circuit which will light a low power consumption LED.
- I'd like for the circuit to be able to light the LED over a wide voltage range so that I can start with a few battery cells in series and the LED will stay lit as the batteries decay and voltage drops
- Since electronics is not my field, it would be great if something like this already exists and can be purchased, or would require minimum soldering or modification
- Maximizing battery life and keeping power consumption low is desirable
What I've found so far:
- What looks the most promising to me so far is the ZXSC310 from Zetec which allows for a battery input voltage of 0.8V to 8V
- There are 3 example circuits given in the ZXSC310 datasheet (http://www.diodes.com/datasheets/ZXSC310.pdf): one for backlighting, one for maximum light and one for maximum battery life
- A ZXSC310 eval board for the backlighting circuit shown on pdf page 6 is available. This circuit isn't too much different from the maximum battery life circuit shown on pdf page 8. Ie: I could remove the capacitor and Shottky diode from the eval board. Then, the only differences would be:
- An FMMT618 NPN would be on the eval board versus a FMMT617 NPN suggested in the "max battery life" circuit. Would this have a major impact on battery power consumption?
- The inductor would be 68 uH versus the 100 uH suggested in the "max battery life" circuit. Would this have a major impact on battery power consumption?
- The sense resistor would be different -- I'm guessing I'd have to swap this out for the 330 mOhm sense resistor suggested in the "max battery life" circuit
- Obviously, there are 4 LEDs in the backlight circuit, and 1 in the max battery life circuit. I could remove 3 LEDS from the eval board
So:
- If I got this ZXSC310 Eval board, and made these modifications, would I accomplish what I set out to do?
- Is there an easier way to do this, another eval board better suited to my goals, or something else I should be looking at?
Further questions:
- If I wanted to remove all 4 LEDs on that board and swap in 1 lower power consumption LED and then supply it with the appropriate amperage or just supply less amperage to 1 unremoved LED that the board comes with, how would I calculate the needed Rsense value (assuming I stick with the boards 68 uH inductor)? How would changing the inductor to the recommended 100 uH change the Rsense calculation.
Finally:
- How do I figure the power consumption and current draw on my battery cell(s) for this circuit at various input voltages?
Ok -- lots of questions; obviously I'm a real newbie. Thank you to anyone who can offer help with any of these questions!
Johnny
Goal:
- I want to be able to hook up a battery cell (or cells) to a circuit which will light a low power consumption LED.
- I'd like for the circuit to be able to light the LED over a wide voltage range so that I can start with a few battery cells in series and the LED will stay lit as the batteries decay and voltage drops
- Since electronics is not my field, it would be great if something like this already exists and can be purchased, or would require minimum soldering or modification
- Maximizing battery life and keeping power consumption low is desirable
What I've found so far:
- What looks the most promising to me so far is the ZXSC310 from Zetec which allows for a battery input voltage of 0.8V to 8V
- There are 3 example circuits given in the ZXSC310 datasheet (http://www.diodes.com/datasheets/ZXSC310.pdf): one for backlighting, one for maximum light and one for maximum battery life
- A ZXSC310 eval board for the backlighting circuit shown on pdf page 6 is available. This circuit isn't too much different from the maximum battery life circuit shown on pdf page 8. Ie: I could remove the capacitor and Shottky diode from the eval board. Then, the only differences would be:
- An FMMT618 NPN would be on the eval board versus a FMMT617 NPN suggested in the "max battery life" circuit. Would this have a major impact on battery power consumption?
- The inductor would be 68 uH versus the 100 uH suggested in the "max battery life" circuit. Would this have a major impact on battery power consumption?
- The sense resistor would be different -- I'm guessing I'd have to swap this out for the 330 mOhm sense resistor suggested in the "max battery life" circuit
- Obviously, there are 4 LEDs in the backlight circuit, and 1 in the max battery life circuit. I could remove 3 LEDS from the eval board
So:
- If I got this ZXSC310 Eval board, and made these modifications, would I accomplish what I set out to do?
- Is there an easier way to do this, another eval board better suited to my goals, or something else I should be looking at?
Further questions:
- If I wanted to remove all 4 LEDs on that board and swap in 1 lower power consumption LED and then supply it with the appropriate amperage or just supply less amperage to 1 unremoved LED that the board comes with, how would I calculate the needed Rsense value (assuming I stick with the boards 68 uH inductor)? How would changing the inductor to the recommended 100 uH change the Rsense calculation.
Finally:
- How do I figure the power consumption and current draw on my battery cell(s) for this circuit at various input voltages?
Ok -- lots of questions; obviously I'm a real newbie. Thank you to anyone who can offer help with any of these questions!
Johnny
