Hello, my name is John Wallace, and I am the applications engineer for Texas Instruments NexFET Power MOSFETs. Today, I'm going to present a tutorial on how to use the Synchronous Buck NexFET Selector Tool, available for download from the MOSFETs' support and training page on ti.com. There are three sheets in the workbook, intro, user input, and equations. The intro sheet includes step-by-step instructions for entering data into the user input sheet and executing the macros which drive pull-down lists for MOSFET selections. It also has a link to TI's E2E support forum for questions, comments, or suggestions regarding the tool and TI NexFET Power MOSFETs. The user input sheet includes a table to enter the Synchronous Buck Converter requirements and Click Here buttons to execute macros for the FET selection process. The blue cells are user inputs. The yellow cells are data sheet values. And the green cells are calculated values. The user can compare up to three different discrete or dual Power block MOSFET solutions for a given set of requirements. This sheet also includes links to MOSFET selectors and a useful, technical article on ti.com. The equation sheet provides the user with detailed mathematical equations used to calculate the MOSFET power losses and a link to the corresponding application report on the TI website. Now, let's walk through an example using this spreadsheet to select FETs for the following design-- 12 volts in to 1.8 volts out with 15 amps of load current switching at 450 kilohertz. Download and open the spreadsheet. Make sure macros are enabled for proper functionality of the tool. Select the User Input tab and enter the system parameters; Input Voltage, 12 volts; let's use 5-volt gate drive; output voltage, 1.8 volts; output current, 15 amps; switching frequency, 450 kilohertz. Target efficiency is used to calculate duty cycle as shown in the equation sheet. Let's assume 93% efficiency. The target ripple ratio is used to calculate the minimum output inductor value. We'll use a ripple ratio of 25%. This yields a minimum output inductor value of 0.97 microhenry. Pick the closest standard value of one microhenry for this example. The next several parameters can usually be found in the control IC or gate driver IC datasheet. We'll leave those at their default values. Lastly, enter the MOSFET junction temperature to calculate RDS(ON), which has a positive temperature coefficient. For this example, we'll use 50 degrees Celsius. You can now see that the calculated operating conditions are summarized in the green cells below the system parameters. Changing any of the system parameters will automatically update these values. Next, click on the big blue button to start the FET selection process. This automatically selects cell F11, which is a pull-down list to select either single discrete or dual-power block for the first FET solution. We'll pick single discrete. Next, click on the blue Click Here button in cell F12 to execute the macro that calculates the power loss for all of the possible synchronous FETs. Pick the sync FET from the pull-down list in cell F15. The list is sorted from minimum to maximum power loss and includes power loss, part number, package, and 1K pricing. The yellow cells display MOSFET parametric data and a link to the datasheet on the TI website. Now, click on the blue Click Here button in cell F26 to execute the macro that calculates the power loss for all of the possible control FETs, and pick a control FET from the pull-down list in cell F27. The first MOSFET solution has now been selected, and the power loss and cost is summarized in the green cells. We can repeat the process for a second FET solution, starting with the pull-down list in cell G11. This time, we'll select dual-power block configuration. Click on the blue Click Here button in cell G12 and then select the synchronous FET from the pull down list in cell G15. Now, click on the blue Click Here button in cell G26 and select the control FET from the pull-down list in cell G27. Since both FETs are integrated in the same package, the selection for the control FET is limited to a single part, the same as the sync FET. Lastly, repeat the process for a third FET solution, starting with the pull-down list in cell H11. Now, we have a comparison between our three MOSFET solutions for the same system requirements, as summarized in the green cells. Changing any of the system parameters will automatically update the calculated power loss. However, if you want to select different FETs while keeping the same system requirements, always start from the top of the FET selection table in row 11 and select the FET configuration. And make sure to execute the macro by clicking on the blue Click Here button in row 12. If you would like to clear all of the FET selections and start over, simply click on the big blue button to restart the FET selection process. Thank you for your attention.

This tool estimates FET power losses and allows the user to compare up to 3 different FET solutions including discrete and power block MOSFETs.