Automotive 3/6/9A driver - feeler thread
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mulderfox01
Newly Enlightened
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- Sep 1, 2010
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Would have to see actual specs before ordering, but i'd probably take a few
Imapilot
Newly Enlightened
I am looking to build something for a small motorcycle's electrical system as well. I obviously don't know the complexities of it yet. But ready to go drivers are a good start! I think after seeing the rallys this year with all the LED lighting, Its a market that can only grow from here.
DIWdiver
Flashlight Enthusiast
Yes, it looks like I will be doing it. I'm starting a PCB layout now.
Don't get too excited yet though, it may take a while.
I'll let you know when I know for sure what it will look like.
Don't get too excited yet though, it may take a while.
I'll let you know when I know for sure what it will look like.
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DIWdiver
Flashlight Enthusiast
Okay, the board layout is done and I'll have prototypes in a few weeks. Here are some specs on the protos:
Board size: 1.25" x 1.375" (32mm x 35mm)
Max Height: about 0.36" (fixed voltage version), about 0.42", adjustable version
Output Current: up to 13.5A
Input Voltage (operating) 10-15V
Input Voltage (withstand) 0-85V
Dropout voltage: 0.2V at 10A
Modes: 2 (high, low)
Mode selection: jumper, switch
Control:
-fixed version can be controlled by PWM or by external potentiometer
-adjustable version has on-board potentiometer for 0-fullscale adjustment
-compatible with HALLSW and HALLTG from Taskled (by design, not tested)
-High and Low modes are proportional to control value.
Thermal protection:
- onboard thermistor to protect driver
- input for external thermistor to protect LED (compatible with thermistor on CSM modules from Luminus)
Transient suppression: 85V unidirectional TVS diode.
Cable recommendation: For external control with cables exceeding 12" in length, it is recommended to use shielded cable, with shield grounded only at the driver end. Control can be on wire as small as 30 awg, power cable should be determined by max current, cable length, and allowable voltage loss.
Behavior below 10V is not guaranteed. I expect output current will decrease monotonically with falling input voltage, but this is not tested or guaranteed.
It is important to connect the LED(s) to the driver only when the driver is not powered. This includes momentary interruptions, as with poor connections. It is recommended to solder all connections between the driver and the LED before the driver is powered.
Please note: due to time lag between junction temp and thermistor temp, thermal protection will NOT protect against large overloads like shorted LED, missing heatsink, etc.
Thanks to Semiman, the driver will shut down if the input voltage exceeds 15V. It will restart automatically when the voltage drops below 15V. This will protect the driver and the LEDs from things like 24V jumpstart, load dump, etc. It will have no effect on a vehicle in normal operation.
Cost: TBD (in the next few days)
Adjustable version will be about $2-3 more than fixed current.
Almost everything is still up for discussion. If anyone has suggestions, comments, ideas, or requests, please make them known. LED configurations, current settings, control methods, anything you want to discuss, please speak up.
Board size: 1.25" x 1.375" (32mm x 35mm)
Max Height: about 0.36" (fixed voltage version), about 0.42", adjustable version
Output Current: up to 13.5A
Input Voltage (operating) 10-15V
Input Voltage (withstand) 0-85V
Dropout voltage: 0.2V at 10A
Modes: 2 (high, low)
Mode selection: jumper, switch
Control:
-fixed version can be controlled by PWM or by external potentiometer
-adjustable version has on-board potentiometer for 0-fullscale adjustment
-compatible with HALLSW and HALLTG from Taskled (by design, not tested)
-High and Low modes are proportional to control value.
Thermal protection:
- onboard thermistor to protect driver
- input for external thermistor to protect LED (compatible with thermistor on CSM modules from Luminus)
Transient suppression: 85V unidirectional TVS diode.
Cable recommendation: For external control with cables exceeding 12" in length, it is recommended to use shielded cable, with shield grounded only at the driver end. Control can be on wire as small as 30 awg, power cable should be determined by max current, cable length, and allowable voltage loss.
Behavior below 10V is not guaranteed. I expect output current will decrease monotonically with falling input voltage, but this is not tested or guaranteed.
It is important to connect the LED(s) to the driver only when the driver is not powered. This includes momentary interruptions, as with poor connections. It is recommended to solder all connections between the driver and the LED before the driver is powered.
Please note: due to time lag between junction temp and thermistor temp, thermal protection will NOT protect against large overloads like shorted LED, missing heatsink, etc.
Thanks to Semiman, the driver will shut down if the input voltage exceeds 15V. It will restart automatically when the voltage drops below 15V. This will protect the driver and the LEDs from things like 24V jumpstart, load dump, etc. It will have no effect on a vehicle in normal operation.
Cost: TBD (in the next few days)
Adjustable version will be about $2-3 more than fixed current.
Almost everything is still up for discussion. If anyone has suggestions, comments, ideas, or requests, please make them known. LED configurations, current settings, control methods, anything you want to discuss, please speak up.
Mattaus
Flashlight Enthusiast
This looks very cool. My mind is going nuts as to what I can use them for. Not being too technically inclined please forgive me if the following question is a bit silly but can you explain the dimming/modes etc a bit more? I'm confused because you say it has 2 modes (low/high) but then say a fixed version can be control by a pot, then an adjustable version has an on board pot...I think I understand what's happening (on board versus separated potentiometer, but what's the deal with the high/low modes!?
Also looking at the input voltage and max output current what LEDs and in what quantity do you feel would best be driven? 4 XM-Ls could be driven based on the max output current, but the voltage required is very close to the Vin max. Obviously a car battery wouldn't be able to do this, so it's likely 3 XM-Ls would be the best, though driven at 4.5A each which is a bit much. Is this where the on board pot comes in handy? Set your max output current, and then control the dimming with an external pot?
Or am I way off the reservation here...
Also looking at the input voltage and max output current what LEDs and in what quantity do you feel would best be driven? 4 XM-Ls could be driven based on the max output current, but the voltage required is very close to the Vin max. Obviously a car battery wouldn't be able to do this, so it's likely 3 XM-Ls would be the best, though driven at 4.5A each which is a bit much. Is this where the on board pot comes in handy? Set your max output current, and then control the dimming with an external pot?
Or am I way off the reservation here...
DIWdiver
Flashlight Enthusiast
Yeah, I suppost that warrants a bit finer detail.
The output current is determined by two things: the sense resistor, and the voltage divider.
The sense resistor determines the maximum output current of the regulator. I would expect settings of 3, 5, 9, and 13.5A would be popular, but that's open for input. The sense resistor is something you probably won't fool with after getting the driver, but you certainly could. For example, if you bought a 3A driver and decided later to use SSR-50's, you could change the resistor and have a 5A driver.
The voltage divider is where all the options are. There are two separate dividers on the board, high range and low range. By connecting the H terminal to the C terminal, you engage the high range driver. By connecting instead the L and C terminals, you engage the low range divider. I usually recommend a 4:1 change in current for High/Low, but I can do whatever the customer wants. I'll offer one or more standard configurations, and do custom ones for a small fee.
The high and low dividers share one resistor. The adjustable version replaces this resistor with a potentiometer (pot). The pot will adjust both ranges proportionately, between zero and full. So for example if you had 10A high/2.5A low adjustable driver, and you adjust the pot down to 80%, then you have 10*80%=8A high, 2.5*80% = 2A low.
An external pot can be used as an additional divider. You connect the output of the pot to either the H or L terminal, allowing you to select modes in conjunction with the external pot. You can even use the adjustable version with the external pot. In the previous example, if you connected your external pot through a switch to either H or L, and set the external pot to 40% and the adjustment to 80%, you'd have 10*80%*40% = 3.2A high, 2.5*80%*40% = 0.8A low.
***WARNING: TECHNOBABBLE FOLLOWS***
You might ask why I don't just offer a 13.5A adjustable driver and be done with it. It would simplify things a lot, and I'm considering it. But there is one small problem with that. The driver has an uncertainty of about +/- 0.1% of full scale. This may seem small, but a 13.5A driver would have an uncertainty of +/- 13.5 mA. When you set it to zero output, there might still be 13.5mA flowing. To counteract this I added a -0.1% offset, so that when you set it to zero output, you get zero output guaranteed.
This has the effect of making the uncertainty 0 to -0.2%. On a 13.5A driver, that's 0 to -27mA. If you then adjust this driver down to 1A, your standard low mode is 0.25A or 250mA, the uncertainty (still 0 to -27mA) could now be more than 10% of the setting. Even in this extreme case, that's not a terrible uncertainty (the human eye is barely capable of detecting changes of 10% in light intensity).
***END OF TECHNOBABBLE***
With all that in consideration, I'm seriously considering offering only the 13.5A adjustable version, with 4:1 high/low. Anything else would be custom. Currently the customizaion fee would be $5.00 per order.
The output current is determined by two things: the sense resistor, and the voltage divider.
The sense resistor determines the maximum output current of the regulator. I would expect settings of 3, 5, 9, and 13.5A would be popular, but that's open for input. The sense resistor is something you probably won't fool with after getting the driver, but you certainly could. For example, if you bought a 3A driver and decided later to use SSR-50's, you could change the resistor and have a 5A driver.
The voltage divider is where all the options are. There are two separate dividers on the board, high range and low range. By connecting the H terminal to the C terminal, you engage the high range driver. By connecting instead the L and C terminals, you engage the low range divider. I usually recommend a 4:1 change in current for High/Low, but I can do whatever the customer wants. I'll offer one or more standard configurations, and do custom ones for a small fee.
The high and low dividers share one resistor. The adjustable version replaces this resistor with a potentiometer (pot). The pot will adjust both ranges proportionately, between zero and full. So for example if you had 10A high/2.5A low adjustable driver, and you adjust the pot down to 80%, then you have 10*80%=8A high, 2.5*80% = 2A low.
An external pot can be used as an additional divider. You connect the output of the pot to either the H or L terminal, allowing you to select modes in conjunction with the external pot. You can even use the adjustable version with the external pot. In the previous example, if you connected your external pot through a switch to either H or L, and set the external pot to 40% and the adjustment to 80%, you'd have 10*80%*40% = 3.2A high, 2.5*80%*40% = 0.8A low.
***WARNING: TECHNOBABBLE FOLLOWS***
You might ask why I don't just offer a 13.5A adjustable driver and be done with it. It would simplify things a lot, and I'm considering it. But there is one small problem with that. The driver has an uncertainty of about +/- 0.1% of full scale. This may seem small, but a 13.5A driver would have an uncertainty of +/- 13.5 mA. When you set it to zero output, there might still be 13.5mA flowing. To counteract this I added a -0.1% offset, so that when you set it to zero output, you get zero output guaranteed.
This has the effect of making the uncertainty 0 to -0.2%. On a 13.5A driver, that's 0 to -27mA. If you then adjust this driver down to 1A, your standard low mode is 0.25A or 250mA, the uncertainty (still 0 to -27mA) could now be more than 10% of the setting. Even in this extreme case, that's not a terrible uncertainty (the human eye is barely capable of detecting changes of 10% in light intensity).
***END OF TECHNOBABBLE***
With all that in consideration, I'm seriously considering offering only the 13.5A adjustable version, with 4:1 high/low. Anything else would be custom. Currently the customizaion fee would be $5.00 per order.
Mattaus
Flashlight Enthusiast
OK, so let me get this straight(er) - you have a driver with a maximum output pre-set, and then you can switch between high and low (high being the max output and low being a predefined fraction of that maximum).
Adding a potentiometer allows you to adjust the output of either. So if you're in high mode (say 13A) you can adjust it to 50% (6.5A). I'm assuming this can be done while running giving you a 'dimming' effect? Say your low mode in this example is 5A - if you adjusted your high mode by 50% and then switched to low mode, the low mode would be 2.5A as soon as you switch. The same changes work in reverse as well.
So all if this is controlled by an external switch? I assume it would cycle? So for each press you get on-high-low-off? Then a pot to dim the driver?
Sorry if this is all very basic stuff. I'm one of these 'visual aids' sort of people lol.
Adding a potentiometer allows you to adjust the output of either. So if you're in high mode (say 13A) you can adjust it to 50% (6.5A). I'm assuming this can be done while running giving you a 'dimming' effect? Say your low mode in this example is 5A - if you adjusted your high mode by 50% and then switched to low mode, the low mode would be 2.5A as soon as you switch. The same changes work in reverse as well.
So all if this is controlled by an external switch? I assume it would cycle? So for each press you get on-high-low-off? Then a pot to dim the driver?
Sorry if this is all very basic stuff. I'm one of these 'visual aids' sort of people lol.
DIWdiver
Flashlight Enthusiast
Four XM-Ls at 3.35V is 13.4V. Add the dropout voltage of the driver (0.2V) and you get 13.6V. This is just below the 'typical' voltage in an automobile that has the engine running. So in a 'typical' system, the LEDs would be driven to max current when the engine is running, and would run at lower current when the engine was off. This configuration puts very low stress on the driver.
Three XM-Ls is 10.05V. Add 0.2 for the driver and you still can run at full output power when the engine is off, and until the battery is pretty dead. This configuration puts lots more stress on the driver.
Three SST-x0 in series is something like 11.4V, so it would probably run on full until the battery is somewhat discharged.
Any of these configurations would be the 'preferred' choice, even though they aren't all 'optimum'.
DIWdiver
Flashlight Enthusiast
Yes, although you might have a hard time finding a pushbutton switch that would do high/low/off. Three-position toggle switches are much more common.
Mattaus
Flashlight Enthusiast
Sweet as....all understood now. I look forward to seeing these running (and prices of course)
DIWdiver
Flashlight Enthusiast
Proto boards have been ordered. They should arrive in 2-3 weeks.
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DIWdiver
Flashlight Enthusiast
Yes. And yes, it would.
But, when you shut the engine off the battery voltage drops, and you will no longer have enough to drive the LEDs to full brightness.
You'll probably never run into the guy building a bar with 15 SST-90s. He's in Sweden, IIRC
But, when you shut the engine off the battery voltage drops, and you will no longer have enough to drive the LEDs to full brightness.
You'll probably never run into the guy building a bar with 15 SST-90s. He's in Sweden, IIRC
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DIWdiver
Flashlight Enthusiast
I've priced everything out, and if the design doesn't need significant changes, I should be able to hold the price at $30 USD. And that would include a hardware kit with two mounting screws with locking washers, two thermal pads, and one standoff.
The FET gets sandwiched between the board and the heatsink, with one screw through board and FET into the heatsink. The standoff goes under the other mounting hole, to make up the gap between the board and the heatsink.
Mounting screws are either 6-32 x 1/2" TORX head or M3 x 12 Hex socket head, customer choice.
One thermal pad goes between board and transistor to provide good contact of the thermistor to the FET, the other obviously goes between the FET and the heatsink.
The FET gets sandwiched between the board and the heatsink, with one screw through board and FET into the heatsink. The standoff goes under the other mounting hole, to make up the gap between the board and the heatsink.
Mounting screws are either 6-32 x 1/2" TORX head or M3 x 12 Hex socket head, customer choice.
One thermal pad goes between board and transistor to provide good contact of the thermistor to the FET, the other obviously goes between the FET and the heatsink.
Mattaus
Flashlight Enthusiast
The price is excellent...and the configuration possibilities make these very tempting. When I get around to building my light bar for my car I'll definitely be using this driver. However I am in the process of re-building my Portable flood lights that I built when I first got into LED lighting. Naturally the build is dodgy, the components are cheap and nasty and I can now most certainly do a better job of them.
My question is however (and I guess this comes down to efficiency which I can't seem to find mentioned yet) would I be best using this driver for a 3s XM-L light (at 4A) or something from TaskLED? This driver is clearly geared towards the automotive user, but I wonder how applicable they'd be elsewhere? I can't see any reason not to use this driver? For the record I plan to use LiPo packs for my flood light power supply - not a car battery.
Sorry if I'm clogging your thread up!
My question is however (and I guess this comes down to efficiency which I can't seem to find mentioned yet) would I be best using this driver for a 3s XM-L light (at 4A) or something from TaskLED? This driver is clearly geared towards the automotive user, but I wonder how applicable they'd be elsewhere? I can't see any reason not to use this driver? For the record I plan to use LiPo packs for my flood light power supply - not a car battery.
Sorry if I'm clogging your thread up!
DIWdiver
Flashlight Enthusiast
Efficiency isn't exactly a strong suit for this type of driver. Efficiency is power out divided by power in. Power is current times voltage. Since this is a linear driver, the input current and output current are the same, and thus:
Eff = Pout/Pin = Vout*Iout / Vin*Iin = Vout/Vin.
So to make the driver efficient, you have to have the output voltage near the input voltage. Otherwise the driver just dissipates the excess as heat.
Switching drivers, like those from Taskled, Der Wichtel, and others, use various voltage conversion techniques, which result in the output current being different from the input current, and they can achieve high efficiency even when the input voltage is substantially different from the output voltage. Some switchers can even have output voltage higher than the input, which a linear driver can't do.
Unfortunately, switchers are more complicated and more difficult to properly protect from the nastiness of the automotive environment. I've seen threads describing how to do it, and the results are fairly effective, but they are cumbersome and won't protect from the worst case scenarios. It could be argued that most vehicles will never see a 24V jumpstart or a load dump surge, and that is isn't necessary to protect from these, and it's a valid argument. The IS1011 is very well protected, and everything is in one tidy little package. It's just one more choice in the sea of possibilities.
Let's take a peek at some efficiency numbers. I haven't looked up the efficiencies of the Der Wichtel switchers lately, but IIRC they are in the 85-90% range for most conditions, getting as high as 92% in ideal conditions. Taskled drivers run 89-96% for 3S SST-50.
I'll assume the following: XM-L voltage=3.35V, SST-xx voltage=3.7V, Vehicle voltage=13.8V running, 12-12.8V not running
For the IS1011, or any linear driver:
4S XM-L, vehicle running: Vin=13.8V, Vout=13.4, efficiency = 97% WOW!
4S XM-L, vehicle not running: Vin=12.8, Vout=12.6, efficiency = 98% Yee Haa! (but LEDS are not at full power)
4S XM-L, vehicle not running: Vin=12.0, Vout=11.8, efficiency = 98% yeah, yeah
3S XM-L, running: Vin=13.8, Vout=10.05, efficiency = 73%
3S XM-L, not running: Vin=12.8, Vout=10.05, efficiency = 79%
3S XM-L, not running: Vin=12.0, Vout=10.05, efficiency = 84%
3S SST-90 (or -50), running: 13.8V, 11.1V, eff=80%
not running: 12.8V, 11.1V, eff=87%
not running: 12.0V, 11.1V, eff=93%
For the 4S XM-L configuration, the Taskled and DerWichtel drivers wouldn't be able to drive to full power even with the vehicle running. They would do great with the 3S configurations, though they might not drive the luminus devices to full power at 12V input. You also have the option of running 2S LEDs, though at slightly lower efficiency. That would push a linear regulator to 60% efficiency or less, generating unmanagable amounts of heat at higher currents.
As far as clogging up the thread, these are great questions which I'm sure others are interested in too, so keep asking whatever comes up.
Eff = Pout/Pin = Vout*Iout / Vin*Iin = Vout/Vin.
So to make the driver efficient, you have to have the output voltage near the input voltage. Otherwise the driver just dissipates the excess as heat.
Switching drivers, like those from Taskled, Der Wichtel, and others, use various voltage conversion techniques, which result in the output current being different from the input current, and they can achieve high efficiency even when the input voltage is substantially different from the output voltage. Some switchers can even have output voltage higher than the input, which a linear driver can't do.
Unfortunately, switchers are more complicated and more difficult to properly protect from the nastiness of the automotive environment. I've seen threads describing how to do it, and the results are fairly effective, but they are cumbersome and won't protect from the worst case scenarios. It could be argued that most vehicles will never see a 24V jumpstart or a load dump surge, and that is isn't necessary to protect from these, and it's a valid argument. The IS1011 is very well protected, and everything is in one tidy little package. It's just one more choice in the sea of possibilities.
Let's take a peek at some efficiency numbers. I haven't looked up the efficiencies of the Der Wichtel switchers lately, but IIRC they are in the 85-90% range for most conditions, getting as high as 92% in ideal conditions. Taskled drivers run 89-96% for 3S SST-50.
I'll assume the following: XM-L voltage=3.35V, SST-xx voltage=3.7V, Vehicle voltage=13.8V running, 12-12.8V not running
For the IS1011, or any linear driver:
4S XM-L, vehicle running: Vin=13.8V, Vout=13.4, efficiency = 97% WOW!
4S XM-L, vehicle not running: Vin=12.8, Vout=12.6, efficiency = 98% Yee Haa! (but LEDS are not at full power)
4S XM-L, vehicle not running: Vin=12.0, Vout=11.8, efficiency = 98% yeah, yeah
3S XM-L, running: Vin=13.8, Vout=10.05, efficiency = 73%
3S XM-L, not running: Vin=12.8, Vout=10.05, efficiency = 79%
3S XM-L, not running: Vin=12.0, Vout=10.05, efficiency = 84%
3S SST-90 (or -50), running: 13.8V, 11.1V, eff=80%
not running: 12.8V, 11.1V, eff=87%
not running: 12.0V, 11.1V, eff=93%
For the 4S XM-L configuration, the Taskled and DerWichtel drivers wouldn't be able to drive to full power even with the vehicle running. They would do great with the 3S configurations, though they might not drive the luminus devices to full power at 12V input. You also have the option of running 2S LEDs, though at slightly lower efficiency. That would push a linear regulator to 60% efficiency or less, generating unmanagable amounts of heat at higher currents.
As far as clogging up the thread, these are great questions which I'm sure others are interested in too, so keep asking whatever comes up.
Mattaus
Flashlight Enthusiast
So despite the linear driver, if you can closely match your Vin and Vout, you can still achieve a pretty efficient system. I plan to go for a 4S XM-L system with a 4S LiPo pack. Vin is 14.4V and Vout is 13.4V which still gives me an efficiency figure of 93%. Pretty damn good IMO. Seen as I primarily use this light for camping the ability to plug it into my car via the 12V socket is very handy as well though with a different efficiency value of course.
Another question for you - still driver related but more application specific. I have a converted 2 head halogen work light (now running 3S XM-Ls in each head powered by some cheap DX drivers). I want to use your driver to power the new system (4S XM-Ls in each head) and am trying to decide if I need 2 (one for each head) or can get away with one. Here's my thinking:
One driver with low set to 4A and high set to 8A. I need the switch that controls on/high/low/off to be connected in such a way that when the driver is set to low only 1 head is powered, and when the driver is set to high both lights are powered. Dimming is then provided by an external pot connected as you have previously discussed.
I guess this connection boils down to whether I can electronically disconnect one of the heads via the same switch that is used to switch between modes. Does this make sense and is it possible? I obviously need to avoid accidently smashing 4S XM-Ls with 8A…I guess a connection diagram would help. I might have to look at some double pole, 3-throw switches. Is that the right term lol? :duh2:
Yes this system would be cheaper than 2 drivers, but it's also simpler to build, requires less cooling and only needs one switch and pot.
No matter what count me in for at least one driver for now, likely two.
EDIT: Was reading back through the thread and remembered this:
Does that kill my idea? Seems like it...
Another question for you - still driver related but more application specific. I have a converted 2 head halogen work light (now running 3S XM-Ls in each head powered by some cheap DX drivers). I want to use your driver to power the new system (4S XM-Ls in each head) and am trying to decide if I need 2 (one for each head) or can get away with one. Here's my thinking:
One driver with low set to 4A and high set to 8A. I need the switch that controls on/high/low/off to be connected in such a way that when the driver is set to low only 1 head is powered, and when the driver is set to high both lights are powered. Dimming is then provided by an external pot connected as you have previously discussed.
I guess this connection boils down to whether I can electronically disconnect one of the heads via the same switch that is used to switch between modes. Does this make sense and is it possible? I obviously need to avoid accidently smashing 4S XM-Ls with 8A…I guess a connection diagram would help. I might have to look at some double pole, 3-throw switches. Is that the right term lol? :duh2:
Yes this system would be cheaper than 2 drivers, but it's also simpler to build, requires less cooling and only needs one switch and pot.
No matter what count me in for at least one driver for now, likely two.
EDIT: Was reading back through the thread and remembered this:
Does that kill my idea? Seems like it...
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