Questions tagged [pcb-design]

About designing the boards which carry the components of an electronic circuit. For questions about getting them built instead use PCB-fabrication. If your question is specific to a certain CAD tool, say which tool and version you are using.

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35 views

Do P/N matter for Diff Pair Clock Inputs to FPGA?

I have noticed on a schematic for an FMC card that the differential pairs of a differential LVDS oscillator do not match the corresponding FPGA transceiver reference clock pins. I.e. the P/N are ...
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2answers
34 views

Output enable logic of AM26LS32AID

I am planning to use AM26LS32AID in my design. In order to enable the output pins of this chip, G and #G need to be connected to VCC and GND respectively as per the datasheet. AS per the below logic ...
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67 views

How do we simulate the circuits which have processors. Is there any way we can simulate the circuit before going to the pcb manufacturing?

I'm working on a project on which I'm using a snapdragon 410e processor. I'm done with the circuit design since all the data is available online for designing the PCB. But I want to simulate the whole ...
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2answers
1k views

Designing a PCB that allows to measure current

What is the best way to "debug" the current in a PCB? My (first!) PCB has a 220v->5v PS on it. I would like to measure how much current is using after the PS to monitor how far from the ...
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1answer
38 views

Altium, mixed signal board, convey to PCB designer whether net must stay over analog region of return plane or digital region of return plane

Some oversimplification is necessary to explain my question--please let's not debate PCB layout techniques--I just need help with a simple Altium question. Preface: One solution to making a good mixed ...
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1answer
47 views

Outputting a 1/4 inch TRS male plug from a PCB

I am designing a small PCB that I need to plug into a 1/4" TRS receptacle. The overall setup can either be something like a small dongle (i.e. attaching a male TRS directly to the PCB somehow,) ...
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2answers
61 views

40 MHz clock between 2 ICs

I have an oscillator at 40 MHz which I would like to drive two ICs, 1.8V output. The ICs are in opposite directions so I have opted for star topology of the two clock traces. Trace length for the ...
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0answers
46 views

Using a pull-up resistor and considering rise time for IC input

I have a FPGA based design in which the FPGA is interfaced with several ICs. The I/Os of the FPGA and most of the ICs are 3.3V, except from one where the I/Os are 1.8V. While there is no problem for ...
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1answer
49 views

Copper Weight/Copper Pour Usability in Thermal Management

I'm trying to think of a way to decrease the temperature that my PCB is running at, but I don't want to add a heatsink if I don't have too since I want this board to have as low of a profile as ...
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0answers
30 views

MIPI C-PHY Signal Routing

I've been looking for a good, definitive reference example for MIPI C-PHY signal routing and have come up short. Bear in mind that C-PHY uses a set of 3 signals per lane, with multi-level coding ...
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0answers
36 views

Any glaring mistakes in I2C touch & OLED PCB design?

Would greatly appreciate any expertise/suggestions on solving this problem! In particular have I done anything glaringly stupid when it comes to my PCB design?? I'm trying to get touch control ...
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3answers
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How does junction to case thermal resistance depend on PCB?

Shouldn't the junction to case (top or bottom) thermal resistance depend only on package or IC internals? How do the PCB details play a role as mentioned in footnote 1?
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784 views

Why is the thermal resistance of copper shown higher than FR4 in below snap?

I see similar W and L for both Cu and FR4. Why is the Cu thermal resistance shown higher than FR4? Is it because of Ounz difference? 1 Oz Copper= 34.8um. FR4 seems to have more thickness-> How ...
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1answer
40 views

copper balancing poly on 4 layer PCB

i am designing the 4 layer pcb for the first time. I got typical 4 layer stackup - signal on the top, GND, PWR, signal on the bottom Most of the signals are routed on top, few are on bottom, and ...
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1answer
59 views

What is the right PCB clearance when using mains (220VAC)?

I am trying to detect mains with an ESP32. For that I am planning to use HCPL-3700 When I try to calculate the clearance for mains, I can see this in the KiCad calculator: But when I set ...
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2answers
219 views

Use of an inductor between a digital and analog power supply

Looking at the reference design for an Intel CPU (VCCA_CLKLDO_1P8 is a an analog supply to the PCH Clock), I didn't understand why there is an inductor between VCCA_CLKLDO_1P8_R and +VCCA_CLKLDO_1P8. ...
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2answers
132 views

Please judge my first PCB (Roast my design) [closed]

Below is my first PCB design: an Arduino Micro, ESP01 (wifi), 4 RGB leds and 2 buttons (power and reset). Everything is functioning well on my bread board, so now I want to make a PCB from it. Using ...
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41 views

TVS diodes routing on USB data lines

I have decided to use bidirectional TVS diodes for ESD protection on the USB data lines. Nevertheless, the pads of the diodes create a discontinuity of the tracks. So, what is the best way to route ...
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1answer
69 views

PCB design guidance. Is AC in a power plane a bad idea?

I have a 4 layer PCB board that I am working on a new revision for with the following general layer setup: Top=signal = signal layer middle1 = 5V power plane (with 24VAC subdivisions) middle2 = gnd ...
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1answer
58 views

BM1387 Footprint [closed]

I am designing a USB bitcoin miner, the BM1387 seems like a good candidate but locating its footprint dimensions has proven a challenge, anyone with leads please assist. This is the best resource in ...
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0answers
33 views

Pcb trace width when connecting an ammeter and voltmeter together

After design and simulate my 2 channel voltmeter/ammeter with arduino I came across with an issue about trace width. This is an image with part of the circuit. On +VL and GND I will connect the load ...
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1answer
95 views

I2C interface frozen until reflowed again

I have custom PCB with nRF52832 MCU and two I2C devices sharing same bus, IAM20380 on 0x68 and IAM20381 on 0x69. All works fine, but after a few hours of testing I2C interface freezes when I2C command ...
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0answers
23 views

Can't find 'ltspice.ulp'

Error Message: Can't find 'ltspice.ulp' I am trying to make an ICD-2 clone on Eagle application v9.6.2. When trying to run the simulation linked with LT Spice, the following error is displayed: Can't ...
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2answers
159 views

How to add many I/O lines to a microcontroller for my custom computer keyboard?

I think that this is a design question because I need to know what type of chip to use first, and then I'll go shopping on my own for which one to use. I need to understand how to add at least 90 ...
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1answer
152 views

SDA and SCL for I2C are always low

I designed a PCB board with some sensors (gyros, accelerometers, and etc.) using the I2C protocol to communicate. However, when I use an Arduino UNO as the master, I'm not able to see the waveform of ...
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3answers
43 views

Thin Film Resistors, Deposition On One Side, Parasitic Capacitance if Resistor is placed such that Deposition next to PCB Ground Plane

I have a question for all high frequency and RF electrical engineers. Thin film resistors have a vapor deposition of resistive material on one face of the component. Let's presume that the resistor ...
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5answers
122 views

Cold start heaters for PCBs

I am working on a custom PCB design. The SoC chipset which we use supports only commercial grade temperature (minimum operating junction temperature of SoC chip is 0ºC.) We want to operate the device ...
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1answer
1k views

Purpose of multiple layer PCB without possibility of blind/buried vias?

What's the purpose of multiple layer PCBs (i.e. 4 layer,) when many manufactures like JLCPCB can't produce blind/buried vias as they just support through-vias? Let's say I have an SMD component with a ...
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2answers
48 views

Guideline for Board-To-Board 2.4GHz RF design - multi ESP32 module board

I am working on a design with multiple ESP32 on one board. The selected ESP32 does not have internal antenna, instead it has an IPEX connector for external antenna. On the device we would like to have ...
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0answers
36 views

Is this esp8266 antenna layout any good?

It's the first time I do a design based on ESP8266 ic (not module) and was wondering if this layout is permissible for 2.4Ghz applications. I acknowledge that the trace must be a bit wider to comply ...
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2answers
38 views

FT232RL - leds stay ON until I connect USB cable

I use FT232RL to do USB->UART converter - you can see the relevant part of the schematic below. VBUS is a 5V pin in a USB socket and is only used for FT232. The PCB has another connector for 5V ...
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1answer
30 views

FT232H direct reset pin VCCIO connection

According to the datasheet, on p.19, it is stated that: RESET# should be tied to VCCIO(+3.3V) if not being used. Same applies to SIWU# as well. Since I will not be using both of those pins, I would ...
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1answer
32 views

Is it possible to use generic passives in Altium and update the BOM with part numbers at the end?

I have just started using Altium and am unsure of the best way to deal with generic 'jelly bean' components such as passives, discrete and parts such as 0.1" headers etc. I know I have to make my ...
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0answers
19 views

In Altium how do you replace components placed from 'Manufacturer Search'?

I have just made the lead from Eagle to Altium and am realising how big that leap is! Currently, I am using manufacturer search to place components that I do not have in my own libraries, I search in '...
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1answer
37 views

In Altium, how to open the symbol and PCB footprint of a given component from the schematic view?

I am having a terrible time trying to learn how to use Altium - compared to RS DesignSpark PCB. Everything seems to be all over the place (especially regarding libraries). In DesignSpark, we right ...
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0answers
34 views

Capacitor value for low load capacitance crystal [duplicate]

The crystal I want to use is the ABM8W-12.0000MHZ-4-B1U-T3 (datasheet). I know that to calculate the capacitors for a crystal is: CL = (C1 * C2) / (C1 + C2) + Cstray However, the load capacitance of ...
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2answers
40 views

Vbus led doesn't turn off after disconnecting USB cable

I designed a circuit based on FT232XS (USB bus powered configuration). I placed red Led on vbus, when I disconnect the usb cable the led doesn't completely turn off and (tx, rx) leds start slightly ...
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5answers
2k views

Trace impedance ohm meaning

I've been trying to understand the principle of trace impedance (single ended and differential) for a while, read several articles (all the best google has to offer), but I have still some serious ...
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1answer
33 views

Does recommended creepage distance apply to copper planes under soldermasks?

I have a design that requires around 0.5mm of creepage distance between conductors. TI said in this video that "creepage is the shortest distance between two uninsulated conductors along the ...
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0answers
38 views

How to separate power and ground planes

In my 4 layer pcb i have 5V power supply that converted to 3.8V to power the modem module. The rest part of pcb is: sim card, UART, I2C, PCM pins and antenna connector. I assume need to separate ...
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1answer
78 views

Near end crosstalk saturation in a microstrip transmission line

I am referring to a microstrip PCB transmission line. I simulated the crosstalk situation using Hyperlynx. Please see the below circuit: I kept increasing the trace length and measured the crosstalk ...
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0answers
34 views

How to show pad designators at any zoom in Altium

Below the designators are clearly visible on the pads: But after barely zooming out they disappear: Is there any way to keep them on at lower zoom magnification? I am wasting a lot of time zooming ...
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3answers
2k views

What is this style of PCB called? It's single-sided, with lots of orthogonal jumpers and strange "horns"

A hobby of mine is to take apart discarded electronics -- to see what I can learn. Sometimes, I'm just puzzled. I've seen this style in name-brand stuff, meaning high quantity, like radios and vcr's. ...
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1answer
62 views

Kicad: Are these traces all connected (if on same layer)?

I'm a kicad newbie and I'm attempting to do two things: keep my layers to a minimum (only 2) to keep cost down allowing kicad to draw the lines for me. I'm drawing all of my traces on but the auto-...
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1answer
46 views

Using Kicad & proper part symbols: How do I add these types of parts for through-hole PCB?

Background I am attempting to create a hobbyist PCB (Printed Circuit Board). I'm using some components which I will provide so end-user can assemble them on a PCB (through-hole soldering them on). My ...
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3answers
76 views

Is it possible to route two connectors on a same high speed bus?

I was making a PCB design in which I need to connect a high speed (1Gbps) DSI bus to a FFC connector. The problem is I need to test 2 displays which have different types of connectors so I was ...
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2answers
116 views

What is this flange on an inductor?

Usually I have seen pads beneath inductors. What is the purpose of this flange on an inductor? Why is it constructed like that? Context: I am looking for low profile inductors (<1.2mm) and ...
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2answers
154 views

Are all negative terminals on a PCB effectively the same?

I'm fairly new at this and self-taught, so assume I'm ignorant and my apologies for any incorrect terminology. I'm repairing my 3D printer for the third time, and the previous 2 breakdowns and repairs,...
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0answers
24 views

Crosstalk Near END and Far END Waveforms

I was learning the basics of cross talk(https://www.youtube.com/watch?v=5EeQPxRdurk).I am confused about the orientation of near end and far end cross-talk wave form's.Please see the below figure. ...
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1answer
69 views

How do I combine multiple separate electronic devices onto one PCB?

I'd like to create a PCB that has this I2C multiplexer on it, along with other components (resistors, external I2C device connections) that I deem necessary. However, I don't know where to begin. I ...

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