DIWdiver
Flashlight Enthusiast
Less than the 20 I plan to be able to build.
Automotive 3/6/9A driver - feeler thread
- Thread starter DIWdiver
- Start date
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Hoop
Enlightened
Reserve me two drivers please. They will not be used for automobile purposes.
DIWdiver
Flashlight Enthusiast
Well, there's news, and it's disappointing. The supplier says they shipped on 10/23, but Hong Kong Post says they left Hong Kong today.
That's a bummer.
Will all work out ok though. The water jet shop where I'm having the housing components cut said their machine was down until the 12th. With any luck I'll have the electronics and the housings about the same time.
Thanks for the update.
Anything on 'Drivers 101'?
Phil
Will all work out ok though. The water jet shop where I'm having the housing components cut said their machine was down until the 12th. With any luck I'll have the electronics and the housings about the same time.
Thanks for the update.
Anything on 'Drivers 101'?
Phil
DIWdiver
Flashlight Enthusiast
I'm writing up the review of the final exam for lession 1. It should be finished this week.
DIWdiver
Flashlight Enthusiast
Okay, good news, great news, and well, news.
1. The first chapter of Drivers 101 is done.
2. The board are at the post office! I will get them tomorrow. I'll post a link to the sales thread once I assemble and test the first driver.
3. I'm not sure I can post Drivers 101, at least not easily. Chapter 1 is 13 pages, with embedded TIFs. I'm happy to e-mail it as a Word document to anyone who wants it while I figure out how to post it.
1. The first chapter of Drivers 101 is done.
2. The board are at the post office! I will get them tomorrow. I'll post a link to the sales thread once I assemble and test the first driver.
3. I'm not sure I can post Drivers 101, at least not easily. Chapter 1 is 13 pages, with embedded TIFs. I'm happy to e-mail it as a Word document to anyone who wants it while I figure out how to post it.
DIWdiver
Flashlight Enthusiast
Okay, I built 3 production boards, and they work. The FET doesn't perform as well as the data sheet claims (I shouldn't be surprised), resulting in the dropout voltage being around 0.6V at 13.3A.
I'm going to order some new resistors which will help reduce the dropout voltage, to less than 0.3V. Dropout voltage is proportional to current, so at lower currents the dropout voltage is lower. It also reduces at higher temperature, which is an advantage.
There are a few errata for the first production units:
1. The labels for H and C terminals are reversed.
2. Operation of current adjust pot is backward (turn it clockwise and current goes down instead of up).
3. Dropout voltage is <0.3V, instead of <0.2V at 13.5A.
4. Transient suppression is at 85V. I'm going to reduce this so I can use an 85V FET, which will help reduce the dropout voltage.
5. There is no dedicated terminal for the cable shield. It should be tied to the G or B- terminal.
These errata will all be taken care of in the next run of boards.
I'm going to put up the sales thread and begin accepting orders. I will include a list of those who have expressed interest, and they will get priority on the first 20 units, if ordered within a week of the thread going up.
Additional units will be available about 3-4 weeks after the first ones sell out. I expect to be able to ship by the end of the week.
I'm going to order some new resistors which will help reduce the dropout voltage, to less than 0.3V. Dropout voltage is proportional to current, so at lower currents the dropout voltage is lower. It also reduces at higher temperature, which is an advantage.
There are a few errata for the first production units:
1. The labels for H and C terminals are reversed.
2. Operation of current adjust pot is backward (turn it clockwise and current goes down instead of up).
3. Dropout voltage is <0.3V, instead of <0.2V at 13.5A.
4. Transient suppression is at 85V. I'm going to reduce this so I can use an 85V FET, which will help reduce the dropout voltage.
5. There is no dedicated terminal for the cable shield. It should be tied to the G or B- terminal.
These errata will all be taken care of in the next run of boards.
I'm going to put up the sales thread and begin accepting orders. I will include a list of those who have expressed interest, and they will get priority on the first 20 units, if ordered within a week of the thread going up.
Additional units will be available about 3-4 weeks after the first ones sell out. I expect to be able to ship by the end of the week.
DIWdiver
Flashlight Enthusiast
- Joined
- Mar 10, 2011
- Messages
- 208
Hey DIW, I have 1-2 questions now I made a purchase:twothumbs:thinking:
Can I run 3s4p xml instead of 4s3p? Reason I ask is I just checked my ute (pick up) battery with engine on = 13.5v So with drop out and other losses the leds will be underpowered. Does the V-out need to be greater than I-out?
I don't plan on doing this but just out of curiousity - can 2 setups be run in series on double battery setup (24v)?
Can I run 3s4p xml instead of 4s3p? Reason I ask is I just checked my ute (pick up) battery with engine on = 13.5v So with drop out and other losses the leds will be underpowered. Does the V-out need to be greater than I-out?
I don't plan on doing this but just out of curiousity - can 2 setups be run in series on double battery setup (24v)?
DIWdiver
Flashlight Enthusiast
3S4P, absolutely. You will have to be very careful of power dissipation and heatsinking, but as long as the driver is properly attached to a good slug of metal, it should protect itself.
It isn't the relationship of Vout and Iout that you need to worry about, but the relationship of Vin and Vout. As long as Vin > Vout + 0.2V, you will be in regulation (Iout will be what the driver is set to).
If Vin drops too low, then Vout can't be kept up, and thus Vout and Iout will begin to drop. At this point the driver will look like a fixed resistor, around 0.015 ohms (varies a little from one driver to the next). At this point the current is determined primarily by three things: supply voltage, total system resistance, and LED voltage curves.
As far as stacking two systems in a 24V configuration, I don't know exactly what would happen, but my guess is that one would hit the 15V max, and shut down, while the other would get no power to run the LEDs.
It isn't the relationship of Vout and Iout that you need to worry about, but the relationship of Vin and Vout. As long as Vin > Vout + 0.2V, you will be in regulation (Iout will be what the driver is set to).
If Vin drops too low, then Vout can't be kept up, and thus Vout and Iout will begin to drop. At this point the driver will look like a fixed resistor, around 0.015 ohms (varies a little from one driver to the next). At this point the current is determined primarily by three things: supply voltage, total system resistance, and LED voltage curves.
As far as stacking two systems in a 24V configuration, I don't know exactly what would happen, but my guess is that one would hit the 15V max, and shut down, while the other would get no power to run the LEDs.
- Joined
- Mar 10, 2011
- Messages
- 208
Great. I can't wait to get started. I can see it will be many weeks for me to finish the build and a couple more before I can go blind some kangaroos :naughty:
DIWdiver
Flashlight Enthusiast
Not all in series, but you can run two strings of three, from one driver.
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