Attached is a picture 06 of a measurement of the pixel clk coming from the AM3352 on a design I am working on It is a very sinusoidal signal I would have expected it to be a square wave I do have a 33 ohm resistor in series but I shorted it out in the 07 image All that did was ma ID: 611758
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Slide1
AM3352 pixel clock question
Attached is a picture (06) of a measurement of the pixel
clk
coming from the AM3352 on a design I am working on. It is a very sinusoidal signal. I would have expected it to be a square wave. I do have a 33 ohm resistor in series, but I shorted it out in the 07 image. All that did was make it more sinusoidal. I am also concerned that the signal isn’t reaching either 0V or 3.3V.
Do either of you have any thoughts on this topic? Is there any sort of drive strength control on this chip?Slide2
AM3352 pixel clock question
Picture #6, 33 ohm resistor in seriesSlide3
AM3352 pixel clock question
Picture #7, 33 ohm resistor shortedSlide4
AM3352 pixel clock question
Picture
#8, with series 33
ohm
resistor
Good
question, the
new
scope shots are on a 300MHz scope full bandwidth. I was using a 100MHz scope not on full
bandwidth.
The 100MHz scope still can’t get a good read on the signal at full bandwidth though.Picture 08 has the 33 ohm and 09 is without the 33 ohm. 10 is without the LCD attached and no 33ohm. In 12 I bypassed the PCLK trace with 30 AWG wire, so I don’t think it is the stack up. Single ended 10x passive probe (tek P6139B), DC couplingSlide5
AM3352 pixel clock question
Picture
#9, without series 33
ohm
resistor
Picture 08
has the 33 ohm and 09 is without the 33 ohm. 10 is without the LCD attached and no 33ohm. In 12 I bypassed the PCLK trace with 30 AWG wire, so I don’t think it is the
stack up.Slide6
AM3352 pixel clock question
Picture
#10 – LCD not connected
Picture 08
has the 33 ohm and 09 is without the 33 ohm. 10 is without the LCD attached and no 33ohm. In 12 I bypassed the PCLK trace with 30 AWG wire, so I don’t think it is the
stack up.Slide7
AM3352 pixel clock question
Picture
#12 – PCLK bypassed with 30 AWG wire
Picture 08
has the 33 ohm and 09 is without the 33 ohm. 10 is without the LCD attached and no 33ohm. In 12 I bypassed the PCLK trace with 30 AWG wire, so I don’t think it is the
stack up.