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Thanks for the reply man.
What's causing this current ripple when the PWM is turned low?
So I've calculated everything up and came up with the following.
Vin – 12vdc
Vout – 3.1vdc
Iout– 350mA
Led driver – LT3517
Led – Cree Xlamp XM-L Color (White Die)
IC frequency – 500kHz
Pwm frequecy -...
Thanks for the help guys!
Inductor current ripple, was just curious if 30% is a good percentage to go by.
And I read in a texas instrument document that 25mV is a good rule of thumb for max Vout ripple P-P. Do you guys agree?
All,
What is a good value for "desirable voltage ripple" on the output of a smps powering a high power LED?
Cout (min) = ΔI / 8 • Fsw • ΔV.
Cout (min) = 0.115 / 8 • 0.09 • ____
Thanks guys.
PS. The document I'm reading from Linear Technology states that a good current ripple is %30. Do you...
Thanks for the responses, here's the file. Really appreciate the help!
- - - Updated - - -
Wow, thanks!
Tied ramp pin to ground to bypass spread spectrum frequency modulation and now the current ripple looks like this:
If you guys don't mind helping me with the proper way to size the...
All,
How's everyone doing? I hope everyone is doing well.
I need some help with the method/formula for selecting an out capacitor for my boost regulator. Any help is greatly appreciated.
In the manual for the LT3795 everything has a description with formulas for selecting all the components...
All,
Re-routed it, took out the power planes, and tried keeping everything off the bottom plane.
Do I need to separate the four ICs on the bottom layer ground pour, will connecting all of them together with a copper pour on the bottom create ground loops?
With four of these it's like...
All,
Question on the grounding.
With four different ICs controlling four different dies on one LED makes it impossible to put image ground plane under where the current flows through each IC without creating ground loops.
Any advice on how I can have four separate ground pours under each IC...
I'm an service electrician on drilling rigs, when spec'ing anything there are rules and regulations that make sure the job gets done right and that it's safe.
I follow the NEC and IEC here in America, I'm not sure who regulates the PCB design world, but I want to follow their standards to make...
Barry,
It's just hobby level, and my first build. But, I like to challenge myself to learn and do the job right, it's more satisfying when your finished and you also learn a lot while doing it that way.
Are there any rule of thumb calculations and practices that will keep the EMI within...
All,
This is my first PCB build and I've got some questions before finalizing and moving to fabrication.
It's a 2 layer board, with led drivers (for RGBW), 12 volt supply, LED drivers running at 2mhz, and a maximum of 4 amps, 1 amp per color die.
The inputs at the bottom are; White, Red...
Thanks for all the information. I guess certain things will come with the more experience I get with designing PCBs. Of all the
forums that I'm a member of this is the most informative one out there, every time I ask a question you guys give answers.
What I needed to do was to change the rank...
All,
Thank you guys for your help! Very helpful community.
I reverted my footprint as per LGA layout of all pins, connected them all to their corresponding pins so only show 1 pin in symbol.
Is it okay to put a polygon plane over the common pins for one signal with no thermals? Will this...
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