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Hi guys,
I'm in the middle of designing of an input filter for a power supply with an active PFC circuit. The power supply needs to comply with IEC 61000-3-2 for conducted emissions. I'm reading through the standard, but I'm having difficulties finding anything on the high frequency parts.
The...
Hi guys,
I'm designing an 8-layer impedance controlled PCB. The fastest signals on it will be 303 MHz DDR3. My PCB manufacturer recommended me to use the Panasonic R-1650M prepreg material. The 1080 prepreg has the dielectric constant, Dk, specified as:
1MHz: 4.6
1GHz: 4.1
The 303 MHz digital...
Hi Guys,
I'm playing around with a 320x240 TFT LCD and a LPC1788 microcontroller (which has a LCD controller built-in). What I've noticed is that when I display white characters, the black background becomes influenced by those characters (grey-ish lines). See the picture attached.
Does...
Hi guys,
I will be doing my first design with an SDR SDRAM. I'll be using the LPC1788 (in BGA), which has an SDRAM controller built-in, case and a 32Bit 3.3V SDRAM. The maximum speed will be 120MHz. My first question is regarding the layer stackup; would this be correct?
- Top Layer (signal)
-...
OK, I've found the sollution:
1. Use soldermask expansions set to 0 in PCB
2. In CamTastic, when generating gerbers, there is a "scale" tool, which allows to to scale any object in %. So select the paste layer and scale all pads by 10%.
So voila. You can't do scaling in the PCB, but you can do...
Hi guys,
I'm strugling through the IPC-7351 standard and there is one thing (well, many actually) that bugs me. The component courtyard is defined as: "Courtyard – The smallest rectangular area that provides a minimum electrical and mechanical clearance (courtyard excess) around the combined...
Now that's a neat Idea that I haven't thaught of, and it would work, but there's a problem. If I decide to make several boards and ship the files to a manufacturer, the Paste layer must be 1:1 with the pads (ie expansions set to 0). If I modify the expansions in the library for each component...
Hi guys,
I'll be doing my first reflow soldering (bought a reflow oven) and I need to make a soldering stencil for my PCB. I am working in Altium designer 10. I have two questions:
- The pads in the Top Paste layer should be 10% smaller for the SMT stencil. How do you scale all pads in AD by 10%...
Hi guys,
I have 30V 50A MOSFET H-Bridge (at about 20kHz PWM), as well as a MCU with a 12-bit ADC on a 4 -layer PCB. The bridge is on the top layer and the MCU is on the bottom layer, but not directly under the bridge. The bridge will for sure generate disturbances which might influence the ADC...
Hi guys,
I'm making an H-bridge bith 4 mosfets, 2 N-type and 2 P-type, to drive a DC motor (12V, 10A). I only need it to run forward or backward; no PWM.
My question is, do I need to put diodes in parallel with the mosfets (to protect the mosfets from voltages induced by the motor)?
In theory...
Hi guys!
I have a battery powered PIC12F MCU and I have a 4.7V zener diode at the input, to protect it against any overvoltages. The diode is a NXP BZV55 series, 4.7V. The problem is, that the zenner diode has a very high leakage current, about 600uA @ 3.6V and 1100uA @ 4.2V, which is...
Hello,
I'm trying to calculate the magnetizing current of a Current transformer, but I cannot find the equation anywhere. Can anyone help me out?
George
Hi guys,
I'm playing around with the simulation of a Full Bridge ZVS converter. My problem is, that I do not fully understand how to determine the value of the leakage inductance the transformer must have. In the sumulation (see the schematics) the output amplitude is dependant on the value of...
Hi,
I have the ICD3 and I need to program a 12F683. The thing is, that I really need one extra pin, so I need to use the GP3/MCLR/VPP pin as IO. My question is, can the ICD3 generate 12V on MCLR to program the PIC? I've been through the user guides, but I cannot find this info.
Best regards,
George
Hi guys,
I have just calculated a design for a power inductor on an ETD-59 core. In the worst case possible, the copper losses are 16W; since the frequency is low (only 50kHz) the core losses are negligent. The current density at this point is 820 A/cm^2 which I know is quite high.
So I would...
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