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  • Author Author: doctorcdf
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Richtek EVB_RT7275GQW Evaluation Board

doctorcdf

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Richtek EVB_RT7275GQW Evaluation BoardThe Richtek EVB_RT7275GQWRichtek EVB_RT7275GQW is an evaluation board for RT7275GQW device. The RT7275GQW is a high performance 3A step down regulator with an internal power switch and synchronous rectifier. It features quick transient response using its Advanced Constant On Time (ACOT) control architecture that provides stable operation with small ceramic output capacitors and without complicated external compensation, among other benefits. The input voltage range is from 4.5V to 18V and the output is adjustable from 0.765V to 8V. The proprietary ACOT control improves upon other fast response constant ontime architectures, achieving nearly constant switching frequency over line, load and output voltage ranges. Since there is no internal clock, response to transients is nearly instantaneous and inductor current can ramp quickly to maintain output regulation without large bulk output capacitance. The RT7275GQW is stable with and optimized for ceramic output capacitors.
  • Default input voltage of 12V
  • Default output voltage of 1.05V
  • Good power output
  • Adjustable soft start
  • Overcurrent protection
  • Cycle by cycle current limit
  • Hiccup mode output over and undervoltage shut down
  • Internal 90mohm switch and 60mohm synchronous rectifier
  • Steady 700KHz switching frequency at all load currents
  • More information: http://www.richtek.com/assets/evb_file/UG7275GQW-00.pdf
Applications:
  • Power Management
  • Industrial
  • Consumer Electronics
  • Portable Devices
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  • Testers will be selected on the basis of quality of applications: we expect a full and complete description of why you want to test this particular product.
  • Testers are required to produce a full, comprehensive and well thought out review within 2 months of receipt of the product.
  • Failure to provide this review within the above timescale will result in the enrolee being excluded from future Road Tests.
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Anonymous

  • Just got mine this evening. Time to blast some chiptune and begin testing! Did anyone want me to test for anything specific? I've got access to fancy university oscilloscopes, function generators, infrared thermometers and such, so I intend to test its response time at various input/output voltages, and frequencies while varying the load at various frequencies, verify the info on the datasheet holds true, as well as push it to its lower, then upper operational limits, all while monitoring the temperature of the components and certain areas of the pcb. Maybe even swap out some of the smds to see how fussy it is. I'll also investigate the purpose of the holes. Offhand, my guess would be that, while they do connect ground on either side of the board they are mainly for cooling purposes/to cope with 3A, otherwise the 2 ground leads would suffice. Let me know if your interested in testing anything else, and I'll do my best =D

  • Good morning and thanks to all who applied for this RoadTest.  We've picked:
    • Dylan Dailey
    • Steven Koster
    • Arun Magesh
    • Peter Oakes
    • Gerrit Polder
    Please note: due to heavy volumes at our warehouse, we are experiencing shipping delays.  Thank you for your patience.
  • in reply to waelect

    I would expect it should be ok, 18V @166mA is not the dissipation in the regulator, it is the energy transfer to the load AKA 3W and is an average

     

    internally the FET switches will be either full on or full of, fully on the resistance will be measured in the milli-ohms so the power loss there will be minimal

     

    A boost regulator is far worse and the ones I have used still barely get warm to the touch

  • in reply to Robert Peter Oakes

    It will be interesting to see the road-test on this one. still 18V at 166mA is still quite high based on the datasheet. but whether I am interpreting the datasheet correctly is yet to be determined.

     

    I don't have the time to do it myself so I will watch this with interest.

  • It appears to be a basic BUCK regulator albeit with a very large inductor for the size of the control IC. As such there very efficient and of course do not generate any significant heat, even with 18V in and 1V out at 3A, that's a 3W load but still only 3W in from the source 18V too so only 166mA would be drawn from the supply (Less inefficiencies). The regulator (Switching circuit) will barely break a sweat

  • in reply to Workshopshed

    Hi Andy, it appears to be a FET switching so drop-out voltages are not the main issue.

     

    I found the datasheet to be extremely limited though, i wanted to locate the maximum power rating at the higher voltages and could not locate anything other than 2.6W and 1.67W. But this is conflicting as this equates to less than 3A even at 1.05V. It is possible the massive number of holes could be heat sink stitching to peak offer better thermal conductivity but overall the spec sheet seem to only be catered for 1.05V.

  • The RT7275GQW looks like a useful chip. I'm afraid I don't have to test equipment necessary to do a decent road test on it though.

     

    Some questions

    I can't seem to find what the dropout voltage is, i.e. if I wanted 5v on the output what is the minimum voltage I could place on the input?

    The description says that there is no internal clock but there is a 700kHz Switching Frequency, can you clarify what that means?

    I'm fasinated by all the holes in the PCB, is that simply so that there is enough copper connecting the PCB layers to cope with the 3A load or is there another reason for it?