In this tutorial we are going to learn about WHAT IS PCB DESIGN FLOW ?
Design Flow Process
Create a set of PCB design flow processes that can used as a guide to step you through the development of a PCB layout. If we follow the best design flow then its helps you avoid duplicating steps. Once you have completed a step, you should never need to repeat it on that design.
1. DESIGN REVIEW
̈ The best design review should take place between all applicable disciplines: i.e. hardware Engineer, Project Management, Layout, Mechanical & Manufacturing. For the PCB designer the following information needs to be determined: Layer stack-up & plane layers, PCB thickness & board material, default trace width, component complexity & qty of new components, proto board or production, auto route or manual route, high speed rules, impedance control, test ability and Schedule.
2. COMPONENT DATA SHEETS
Engineering Dept will submit all component data sheets prior to the start date of a PCB layout, of all of the components that can’t be located in your Library Handbook.
3. MECHANICAL DATA SHEET
Engineering Dept will also provide a Board Outline constraint drawing if one is available/ ASAP The mechanical drawing should be drawn from the top side, include all mounting holes, fixed connector locations, indicate the Layer Stackup & board thickness of the PCB.
4. PART NUMBER & BOARD NAME ASSIGNMENT
After the Engg Dept submits the data sheets, a part no & a board name is assigned to PCB.
5. LIBRARY MANAGEMENT
As you create library parts, using the naming convention that you developed, populate the applicable blank pages with the new decals, representing the pin assignments & all applicable notes & documentation for each part. Keep the PDF file “Up to Date” every time new parts are built.
6. CUSTOM BOARD OUTLINE
̈ Select the correct “Start File” that matches the layering scheme that the Engr has provided & copy the master “Start File” to a new name.
̈ Fill out the Title Block.
̈ Enter the Board Outline.
̈ Add all Mounting/Tooling Holes & Fiducials that are necessary then glue them down.
̈ Move the Targets to the outer extremities of the board outline.
̈ Fully dimension the board edges & at least one mounting hole.
̈ For auto routing should be Create the “Auto router Keep-in or out” inside the Board Outline.
7. STANDARD BOARD OUTLINE
̈ If a Std Board Outline is selected from the Library, the Designer will fill out the Title Block & edit the
text on Layer 26 that will eventually go on the Silkscreen.
̈ Setup the correct Layer and Color Scheme.
̈ At the start of the PCB design, the Engg Dept will provide a net list, from the schematic capture tool.
̈ The net list will contain all of the correct Shape Names.
̈ The net list will not contain Pin Names over 4 characters long.
As per given name of PIN should be as per this : Collector = C, Emitter = E, Base = B, Anode = A,
̈ Import the net list into Package. If errors are found, in the net list, the Designer will report them to
the Project Engineer. The Project Engineer will fix the problems & provide the Designer with an
̈ After the net list is successfully imported into layout, the Designer will Disperse the parts.
̈ Create and e-mail to Project Engineer Unused Pins, Part List 2 & Statistic Reports.
̈ PCB Designer must review and make the list for unused components which have two pin.
̈ Project Engineer also must review Unused Pins list of schematic which main project part.
̈ The Designer & Engineer will perform the part placement or Engineers suggested layout.
̈ The placement must meet the Engrs guidelines & design rules. Engr will provide the DRC.
̈ The placement must meet all manufacturing requirements.
̈ The placement must meet all routability requirements.
̈ Tools/Verify Design – check clearance to ensure no over lapping parts.
11. SPLIT PLANES
̈ Use CAM Plane option & use a 2D-Line to separate the different Plane Nets, or use the Split or Mixed Plane option.
̈ Use the View or Nets feature to discriminate different nets by color.
̈ Create Silkscreen (use 0.1mm snap grid) and bottom side etch text.
̈ All Ref designators must be moved outside component, & must not exceed 2 different rotations. All Text like company logo and REV must be board inside on TOP side . Default text height/width is .080”/.008” Minimum height/width is .060”/.006”.
In this article, we are going to discuss about route of clock signal. Clock Signal: Depending on the length of the clock o/p line, one of the 2 termination schemes should be used. Types of Clock Lines: Short Clock Lines – When a Clock lines one inch or less in length can be connected directly from the clock output pin to the clock load. A series damping resistor is not required for short traces (one inch or less). Matching the output driver impedance plus the series damping resistor to the PCB trace is not necessary. Long Clock Lines – When a Clock lines one inch & longer must be treated as a transmission line. A series damping resistor must be used to match the impedance of the output driver plus the damping resistor to the PCB trace. Matching the impedance will minimize the EMI of the system & eliminate signal reflections back to the driver. The clock line width should be chosen to produce a 60O trace impedance. The PCB trace width varies with the type of mat
In this article, we are going to know about Calculation of current and voltage drop in circuit. Calculation of current in circuit As per below image of circuit one resistor R1 connected in series & Two resistor R2, R3 are connected in parallel . As per Ohm’s Law Formula: I = V / R T As per circuit first we need to calculate the total resistance. Parallel resistance formula: R p = R 2 X R 3 / R 2 + R 3 R p = 20 X 30 / 50 R p = 12 E Now we will calculate the total resistance as per series resistance formula . RT = R1 + RP RT = 10 + 12 = 22 E Now we will calculate the current as per OHM’s Law. I = V / RT I = 9 / 22 = 0.409 A Calculation of voltage drop in circuit As per below image of circuit have one battery & two resistor R1 & R2 connected in series. As per circuit first we need to calculate the total resistance. Series resistance formula: R T = R1+ R 2 R T = 2 + 3 R T = 5 E As per Ohm’s Law Formula: I = V / R T V = I R T 20 = I
In this tutorial we are going to learn about HOW TO REDUCE NOISE FROM POWER SUPPLY PCB AND PCB DESIGN OF CLOCK? 1. REDUCE NOISE FROM POWER SUPPLY PCB A Power Supply noise reduction circuit, consisting of a ferrite bead, filter capacitor, & bypass capacitors for each system VCC, should be implemented. A summary of each component of the power supply noise reduction circuit follows: Ferrite Bead (FB): It is used to block HF noise from the Power Supply . FBs prevents the noise generated by the clk generator from reaching the main PWR supply plane. A minimum of 1.7 Henries is recommended, however, the bigger the FB, the better the noise reduction. Available board space must be considered when choosing the FB’s value because if provides noise isolation only & doesn’t enhance or degrade the performance of a clock generator. Use only those FBs that can provide the rated DC current to the VCC island without saturating. In addition, the DC impedance of the FB must