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The load is typically a high current LED string. I will be controlling VCC so that it provides the bare-minimum overhead to drive the string at the desired current. I'll be able to adjust VCC on the fly based on the drive requirements of the LED string. I hope to keep the power dissipation low...
I need a scale-able high-current (5A) source at 48V supply voltage. I'm looking at this circuit from Linear Tech and it looks like a good starting place. Being able to scale the current by adjusting one resistor, and having the ground connected load, etc...
Can you recommend a circuit that might work here? If I lower the string voltage (the 24v rail), the circuit works
The purpose of this circuit is to "scale" the output. This schematic is simplified; these resistors are sensed by an LED driver to regulate output current.
The goal is to change...
I have a circuit that needs to "scale" the output current, but doing so with this circuit does not always work. The PFET will not turn OFF regardless. If I reduce the 24V rail down to a smaller value than VG (12V), it will shut off.
I realize I probably screwed up this circuit, since the...
Thanks and I appreciate the detailed response.
I have been designing LED illuminators for both continuous and strobe operation for going on 10 years now. I've run the gamut from single 5mm LEDs up to large arrays of hundreds of high power LEDs. I've gone through the exercises that we all do...
I can't use a switching regulator - I have a lot of experience with them and unfortunately they introduce a lot of other issues that I can't have in this design. I've dealt with all the small nuances of drivers like these and theyre are too many trade-offs. I need clean, fast rise-time pulses...
Vision applications, industrial manufacturing, freezing motion for cameras, stroboscopes etc, etc.... this isn't for human vision, so the perceived light output doesn't matter. LEDs used are large arrays, or at least very high current arrays. New high brightness LEDs available can be 10's of...
Up to 50A peak, 1us-1ms. Current output will vary depending on the output pulse-width (thermal limitations and how many capacitors I can fit in the finished package).
Based on a 5VOUT from the MAX9643 (gain of 2.5), a 0.04ohm sense resistor should give the full range up to 50A ( VOUT = ILoad *...
I need some advice on how to connect the feedback from a high-side current source.
Circuit design requirements:
- 48V supply voltage
- LED string length will vary, but can be as long as a ~40V string or more
- LED string must be connected directly to ground to work with an existing system
-...
re: LT3797 "scaleable" current sensing on LED driver
Yes, I am doing that already. I'm using a DAC to control the output brightness. The problem is I am controlling a brightness range from 0-5000mA and if I choose a sense resistor based on 5000mA, I can't get reliable currents below 125mA or...
I'm using the LT3797 LED driver in a SEPIC configuration. It uses a high-side currents sense resistor to set the output current. I'm following this circuit example for my application.
I would like to be able to "scale" the sense resistor on-demand (from a microcontroller) so that I'm able to...
Is it possible to "wear down" a pin on a device by repeatedly writing high or low levels? Not read/write endurance of say an eeprom, but physically toggling a pin high or low.
Specifically, I want to send a reset/presence pulse to a one-wire EEPROM rapidly to determine if the one-wire device...
Wow- I've been a bit out of the loop following this thread, as I have been taken under other tasks... (new baby girl on the way!!)
Thanks for all the replies, this is really great stuff.
Let me give you some background as to why current matching is so important in my field. I design light...
The problem is making a mirror that will work with a few different, already designed, current sources (led drivers). The mirror would be placed din the light and is remote to the current source.
And I don't think bjts would work in all cases because some of the loads are high current and high...
it somewhat works now - I don't know if I had bad MOSFETs or not, or if it was a bad breadboard connection.
I rewired the circuit and it appears to be working> I can short LEDs whilst strobing at 50-60V, 15A per LED string and the current maintains pretty good matching (5-10%). Normal case...
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