- Joined
- Jan 14, 2011
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Introducing...
The BlitzBuck!
The BlitzBuck is a switching, buck-driver with a capability of driving over 2A of output current between 2.5V and 10V input.
The board I have developed for this driver is nearly exactly the size of the FlexDrive with tiny dimensions of 9mm x 12.2mm.
I have tested this driver and on a test load with varying input voltages. Above regulation, the driver will regulate to within 4mA of current. The IC itself is very efficient, but the whole circuit, overall, has an efficiency based on what your input voltage is. For the 445nm diodes, the whole board has an estimated efficiency of approximately 75-80%. This may seem very inefficient, but compared to the linear drivers we have been using to drive 445nm diodes, this is much better over the comparable 60%.
With just a small heatsink on the main IC and a small heatsink on a resistor, one is capable of nearly continuous duty-cycles, assuming reasonable output current.
At the moment, I have no pictures of completed circuits. The reason for this is not that I have never tested this in real life - rather, after having completed the initial test board, I immediately set it to output 1.6A (my test load showed an output of 1.576A) and placed it in a host with a very efficient 445nm diode, powered by two 18650s. I was hasty in this decision because I was very excited. Further, I wanted to see if the current ripple or startup current spike would kill the diode. It didn't! Not proof that it works perfectly, but very good evidence.
Nonetheless, I have placed an order for thirty improved boards (double the output capacitance, better heatsinking for the IC, better ground plane) from Laen. I will be taking a prototyped board (one that has wires in weird places and cut traces - it's not perfect so I didn't want to take a picture to put it here) to my physics department here at Arizona State to be tested on an o-scope to be certain that it is nearly ripple-free, but I am fairly certain of the results.
Assuming the o-scope test goes according to plan, I will begin to start producing these in quantity.
I plan to sell these for approximately $18 shipped.
Enjoy the wait
Oscilloscope Results!
(Note that each division is .2A on the y-axis and 1uS on the x-axis.)
When in regulation:
When just entering regulation or getting to the extremes of the operating range (high voltage):
As you can see, even with the tiny output cap (the production run will have twice the output capacitance), the ripple when in regulation is typically under 100mA. Just on the edges of operating conditions, it will typically have higher ripple, but that's quite common. Anyway, these ripples occur at such a high frequency that really, the diode is simply seeing the average - this is occuring much, much faster than 1MHz - my estimate is probably around 10MHz.
So good results!
The BlitzBuck!
The BlitzBuck is a switching, buck-driver with a capability of driving over 2A of output current between 2.5V and 10V input.
The board I have developed for this driver is nearly exactly the size of the FlexDrive with tiny dimensions of 9mm x 12.2mm.
I have tested this driver and on a test load with varying input voltages. Above regulation, the driver will regulate to within 4mA of current. The IC itself is very efficient, but the whole circuit, overall, has an efficiency based on what your input voltage is. For the 445nm diodes, the whole board has an estimated efficiency of approximately 75-80%. This may seem very inefficient, but compared to the linear drivers we have been using to drive 445nm diodes, this is much better over the comparable 60%.
With just a small heatsink on the main IC and a small heatsink on a resistor, one is capable of nearly continuous duty-cycles, assuming reasonable output current.
At the moment, I have no pictures of completed circuits. The reason for this is not that I have never tested this in real life - rather, after having completed the initial test board, I immediately set it to output 1.6A (my test load showed an output of 1.576A) and placed it in a host with a very efficient 445nm diode, powered by two 18650s. I was hasty in this decision because I was very excited. Further, I wanted to see if the current ripple or startup current spike would kill the diode. It didn't! Not proof that it works perfectly, but very good evidence.
Nonetheless, I have placed an order for thirty improved boards (double the output capacitance, better heatsinking for the IC, better ground plane) from Laen. I will be taking a prototyped board (one that has wires in weird places and cut traces - it's not perfect so I didn't want to take a picture to put it here) to my physics department here at Arizona State to be tested on an o-scope to be certain that it is nearly ripple-free, but I am fairly certain of the results.
Assuming the o-scope test goes according to plan, I will begin to start producing these in quantity.
I plan to sell these for approximately $18 shipped.
Enjoy the wait
Oscilloscope Results!
(Note that each division is .2A on the y-axis and 1uS on the x-axis.)
When in regulation:
When just entering regulation or getting to the extremes of the operating range (high voltage):
As you can see, even with the tiny output cap (the production run will have twice the output capacitance), the ripple when in regulation is typically under 100mA. Just on the edges of operating conditions, it will typically have higher ripple, but that's quite common. Anyway, these ripples occur at such a high frequency that really, the diode is simply seeing the average - this is occuring much, much faster than 1MHz - my estimate is probably around 10MHz.
So good results!
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