## 3-Phase CalculationsJanuary 5, 2008

Here is a Zoho Sheet to do various 3-Phase calculations. It can convert between line-to-line and line-to-neutral voltages, find current based on apparent power (KVA), and choose the required wire cross sectional area to meet the target voltage drop. When designing such a system, you must also meet all applicable laws and safety codes.

It is embedded below (more…)

## Wire Parameter CalculatorSeptember 20, 2007

This Javascript web calculator will calculate the resistance and ampacity for copper wire based on the gauge. Both metric (mm) and American Wire Gauge (AWG) are supported. Note: Ampacity is based on a curve fit to MIL-STD-975. To see the wire table that this calculator is based on as well as important information about wire insulation temperature ratings, click here.

Features:

• Results update as you type
• Several choices of units
• Units and other settings are saved between sessions
• Blog format allows user comments

Inputs:

 Wire Size AWG mm

Optional Inputs:

 Wire Temperature Deg.  C F Wire Length m cm ft inches Number of Wires in Bundle

Results (per each wire):

 Resistance Ohms Single Wire Ampacity Amps Wire Bundle Ampacity (per wire) Amps Copper Diameter mils mm AWG Copper Area mils^2 mm^2 Copper Weight kg g lbs oz

## Hex, Decimal, and Binary ConverterJune 29, 2007

This web calculator converts numbers between the hexadecimal (hex), decimal, and binary formats. The calculator was designed to allow easy conversion between any of these three formats. This task is very common for those working with digital hardware and software including microcontrollers, DSPâ€™s, FPGA, etc. (more...)

## Skin Effect CalculatorJune 18, 2007

Electrical current always flows in the path that results in the lowest expenditure of energy. At lower frequencies, current flows in a path that reduces I^2*R losses. This is the path of shortest distance and is fairly intuitive to think about.

At higher frequencies, things get a little strange. (more...)

## PCB Stack-Up Design And Impedance CalculatorMay 12, 2007

Review: A new PCB stack-up design and impedance calculator is available for download from Istvan Nagy (see link below). It is a full-featured Excel-based tool that helps plan the PCB stack-up so that controlled impedance traces can be effectively implemented. It covers both single-ended and differential traces and is based on the equation s from IPC-D-317A. It allows one to see the range of impedances that are possible for a given layer stack-up. It also has pre-distortion calculations to support high-speed compensation, a unit changer, and a materials library.

layerstack_planningoriginalipc.xls

Do you have a favorite stack-up and impedance calculation tool? Let us know about it in the comments below.

## Transmission Line CalculatorMarch 6, 2007

The Excel based tool (see link below) calculates the capacitance and inductance per unit length as well as the impedance of a transmission line. It may be applied to wires, PCBs, etc. (more…)

## PCB Thermal Copper AreaFebruary 16, 2007

I published the following Zoho Sheet to calculate the PCB copper surface area to cool a device based on its power dissipation.

It is embedded below and can also be opened in its own window.

## Conductive Ink TracesJune 14, 2006

Conductive ink, for example the Dow Corning PI-2000 series of Silver Polymeric Interconnect Materials, can be used to print conductive circuit traces. Generally, the ink is applied using a screen printing technique, with typical print thicknesses of 25 um to 40 um. Sheet Resistivity is specified in milliohms/square at a 25 um print thickness and varies from 8 to 81 for the currently available inks. For comparison, copper has a Sheet Resistivity of 0.68 milliohms/square at a 25 um thickness.

The Sheet Resistivity can be used to calculate the resistance of the printed traces as follows:

Resistance = Sheet_Resistivity*(Length/Width)*(Ref_Thickness/Thickness)

where "Ref_Thickness" is the thickness at which the "Sheet_Resistivity" is specified in the ink's data sheet and "Thickness" is the actual thickness of the ink you are printing.

The Calculator
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## PCB Trace Width CalculatorJanuary 31, 2006

This Javascript web calculator calculates the trace width for printed circuit boards based on a curve fit to IPC-2221 (formerly IPC-D-275). Also see the via calculator.

New features:

• Results update as you type
• Several choices of units
• Units and other settings are saved between sessions
• Blog format allows user comments

Inputs:

 Current Amps Thickness oz/ft^2 mil mm um

Optional Inputs:

 Temperature Rise Deg C F Ambient Temperature Deg C F Trace Length inch feet mil mm um cm m

Results for Internal Layers:

 Required Trace Width mil mm um Resistance Ohms Voltage Drop Volts Power Loss Watts

Results for External Layers in Air:

 Required Trace Width mil mm um Resistance Ohms Voltage Drop Volts Power Loss Watts

Notes:

The trace width is calculated as follows:

First, the Area is calculated:

Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)

Then, the Width is calculated:

Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])

For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725

For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725

where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves

For geometry diagrams, click on the pictures below.