5 Design, Layout, and Manufacturing Support

This section summarizes notes to support the reader to make sensible design choices, selecting the appropriate components and passives, optimizing the PCB layout, ensuring manufacturability and fine-tuning the solution to meet the application’s requirements.

MSL Ratings and Reflow Profiles:SPRABY1

This application reports explains the relationship of MSL rating to the customer production floor life and surface mount reflow temperatures for TI semiconductors.

Long Term Storage Evaluation of Semiconductor Devices:SLPA019

This paper details the ongoing results of studying the quality, reliability, and usability of semiconductor products after long-term storage in a controlled environment. To better understand long-term storage viability, additional data was collected to further comprehend the time that products can be stored before the reliability can be compromised.

Handling and Process Recommendations:SNOA550

This application report provides recommendations for handling, storing, and mounting Texas Instruments' surface mount IC packages. Please reference published IPC-J-STD-004, IPC-JEDEC J-STD-020, and IPC-JEDEC J-STD-033 documents for their latest versions.

QFN/SON PCB Attachment Application Report:SLUA271

Quad flat-pack no-leads (QFNs) and small-outline no leads (SONs) are leadless packages with electrical connections made via lands on the bottom side of the component to the surface of the connecting substrate (PCB, ceramic). This application report presents users with introductory information about attaching QFN/SON devices to printed circuit boards (PCBs).

Benefits and Trade-offs of Various Power-Module Package Options:SLYY120

This white paper discusses a few package options – embedded, leaded and quad flat no-lead (QFN) – and the benefits and trade-offs of each in terms of module size, component integration, thermal performance and electromagnetic interference (EMI) considerations.

HotRod™ QFN Package PCB Attachment:SLUA715

This application report presents users with information about attaching HotRod QFN devices to the printed circuit boards.

SMT Guidelines for Stacked Inductor (Inductor On Top) on Voltage Regulator IC:SLVA764

The following guideline is a step-by-step guide on assembling TI voltage regulator ICs and inductors on top of the IC in a high-volume manufacturing environment where SMT processes are used.

Five Steps to a Great PCB Layout for a Step-Down Converter:SLYT614

This article details a five-step procedure to design a good PCB layout for any TPS62xxx integrated-switch, step-down converter.

Design Considerations for a Resistive Feedback Divider in a DC/DC Converter:SLYT469

This article discusses the design considerations for the resistive divider in a feedback system and how the divider affects a converter’s efficiency, output voltage accuracy, noise sensitivity, and stability.

Optimizing Resistor Dividers at a Comparator Input:SLVA450

This application report discusses several key factors involved with selecting optimally-sized resistors commonly used at the input to a comparator to set a threshold voltage on switching regulator devices, considering efficiency and voltage accuracy constraints.

Optimizing Transient Response of Internally Compensated DC-DC Converters with Feedforward Capacitor:SLVA289

This application report describes how to choose the feedforward capacitor value (Cff) of internally compensated dc-dc power supplies to achieve optimum transient response. The described procedure in this application report provides guidance in optimizing transient response by increasing converter bandwidth while retaining acceptable phase margin. This document is intended for all power-supply designers who want to Optimize the Transient Response of a working, Internally Compensated DC-DC Converter.

Choosing an Appropriate Pull-up and Pull-down Resistor for Open Drain Outputs:SLVA485

This application report discusses when to use a pull-up or pull-down resistor at open drain outputs commonly found on ICs, for example Power Good (PG), the factors that should be considered when selecting a pull-up or pull-down resistor, and how to calculate a valid range for the value of the resistor.

Achieving a Clean Startup by Using a DC/DC Converter With a Precise Enable-pin Threshold:SLYT730

Most DC/DC Converters contain an enable (EN) pin input that is used to control the startup behavior. This article explains some common EN-pin threshold specifications found in device data sheets and describes several application circuits that provide a clean startup, with or without using a converter with a precise EN-pin threshold.

Extending the Soft Start Time Without a Soft Start Pin:SLVA307

In battery-powered equipment, extending the soft-start time can be crucial to a glitch-free start-up. Especially toward the end of a battery's life, the voltage drop and increasing impedance of the battery from excessive inrush current into the power supply can be a problem. This application report demonstrates a simple circuit that extends the soft start time and reduces the inrush current, taking the examples of the TPS6107x family of boost converters.

Adjusting the Soft-start Time of an Integrated Power Module:SLYT669

This paper demonstrates three simple and low-cost solutions to adjust the soft-start time of an integrated power module and provide clean, acceptable start-up in applications with special soft-start requirements, particularly in FPGAs, which have lots of output capacitance or may draw large currents during the soft-start time.

Sequencing and Tracking With the TPS621-Family and TPS821-Family:SLVA470

This application note describes how to use the EN, PG, and SS/TR pins in tracking and sequencing applications.

Understanding the Absolute Maximum Ratings of the SW Node:SLVA494

This application note explains the operation of a synchronous buck converter, demonstrates why the SW node negative rating might be exceeded during switching operation, gives guidance for properly measuring the SW node voltage, and provides good layout practices for synchronous buck converters.

Minimizing Ringing at the Switch Node of a Boost Converter:SLVA255

This application report explains how to use proper board layout and/or a snubber to reduce high-frequency ringing at the switch node of any switching converter, using a boost converter as an example.

I_Q: What It Is, What It Isn’t, and How to Use It:SLYT412

This article defines I_Q and how it is measured, explains what I_Q is not and how it should not be used, and gives design considerations on how to use I_Q while avoiding common measurement errors.

Understanding Eco-Mode™ Operation:SLVA388

To maximize efficiency, the output power must be maximized or the power dissipation must be minimized. When the load current is low, the output power will also be low, so the only way to increase efficiency at light loads is to reduce power dissipation in the converter. The losses in a dc/dc converter can generally be divided into three categories; conduction loss, switching loss and quiescent loss.

Agency Requirements for Standy Power Consumption with Off-line and PoL Converters:SLYT665

This article highlights new techniques used by new flyback and secondary-side controllers, and compares two complete POL architectures with and without the lightload efficiency feature. Also covered is the energy-saving advantage gained when selecting a POL solution with light-load efficiency features.

The Forgotten Converter (Charge Pumps):SLPY005

This white paper discusses the pros and cons of charge-pump converter topologies, provides industrial and personal electronics application examples, and covers component-selection guidelines.

Demystifying Input Supply Current in DC/DC Regulators: From Shutdown to Full Load:SLYY189

Quiescent current can be one of the most confusing specifications of a DC/DC converter, especially if you are not familiar with the detailed operation of a switching regulator. Because manufacturers use different terminology and definitions, you will often see quiescent current, IQ or input supply current used interchangeably. This paper explains the differences and clears up any confusion.

How the Switching Frequency Affects the Performance of a Buck Converter:SLVAD3

The buck converter uses an inherent switching action to regulate voltage. This switching frequency can affect the performance of a buck converter, and is thus very important. This application report analyzes the influence of switching frequency on buck converter performance in terms of efficiency, thermals, ripple, and transient response.

Methods to Solve Reverse Current-caused Damage in Synchronous Buck Converter:SLUA962

Reverse current is a common phenomenon that occurs in synchronous buck converters. If the reverse current is large enough, the low-side field-effect transistor (FET) is very likely to be damaged. Since this issue is relatively common in synchronous buck converters, it is worth investigating the mechanisms that lead to reverse current and the subsequent damage that it causes. At the same time, it is important to understand potential solutions to eliminate this condition altogether. In this application note, four such solutions are presented and evaluated.

Understanding Flip Chip QFN (HotRod™) and Standard QFN Performance Differences:SLAEE1

Many recently released DC/DC converters use Flip Chip Quad Flat No-lead (QFN) or HotRod™ (HR) QFN package technology to maximize their performance. However, HR QFN package technology typically lacks the large thermal pad present on the bottom of standard QFN packages. A common question for end equipment where thermal performance is a key concern due to high ambient temperatures is whether the HR QFN package can meet the thermal requirements. This application report compares the performance of the HR QFN and standard QFN packages using measurements taken with the TPS54824 and TPS54A24.

Understanding Power Module Operating Limits:SLUAAC9

This application report will discuss the driving factors behind a module’s operating limits, to help engineers select and configure power modules most effectively in their designs. The TPSM5D1806 dual 6-A output buck power module is used as an example for the discussions in this application report.

The Stability of a D-CAP2™ Converter with Different Kinds of Capacitors:SLVAE93

This application report discusses the stability of D-CAP2 converters with different kinds of capacitors, especially electrolytic and polymer capacitors.

Benefits Using a Buck Converter's External Vcc Bias Pin:SNVAA16

his report compares the power losses of 16-V, 15-A TPS548A28 and TPS548A29 synchronous step-down converters when using internal and external bias voltages in a multi-rail point-of-load system. Both devices have the same integrated power stage but have a different internal LDO voltage.

Understanding OOA™ Operation:SLUA946

This application note presents a detailed introduction to this feature based on the TPS566235, including the audio noise generation mechanism, OOA operation behavior, and the performance characteristics.

Multi-Function Pins for Easy Designing:SLVAF56

A multi-function pinout is when two or more features are integrated into one pin. A table found in the device’s data sheet is used to decipher what features are available with guidance of how to select the desired combination.

Stability Analysis and Design of D-CAP2 and D-CAP3 Converter – Part 1: How to Select Output Capacitor:SLVAF11

D-CAP series control schemes are widely used in TI buck controllers/converters due to the advantages of good dynamic performance and less external components. In D-CAP2 and D-CAP3 schemes, the limitation on the use of small ESR capacitor is broken through with the internal ripple injection circuit.

Stability Analysis and Design of D-CAP2 and D-CAP3 Converter – Part 2: How to Select Feedforward Capacitor:SLVAF45

In the previous application report SLVAF11, the method to select output capacitor for D-CAP2/D-CAP3 converters without feedforward capacitor (Cff) is introduced. On the basis, the method to select Cff is further studied in this application report. First, the necessity to add a Cff for stability in D-CAP2/D-CAP3 converters with high output voltage is analyzed. Then the impacts of Cff on the converter loop are introduced. Combining the Cff impacts and D-CAP2/D-CAP3 loop characteristics, a method to select Cff for stability is proposed by ensuring -20dB/decade slope at converter loop gain crossover frequency.

Designing with small DC/DC converters: HotRod™ QFN vs. Enhanced HotRod™ QFN Packaging:SLYT816

In this article, we will take a look at two point-of-load DC/DC converters, providing up to 20 A with the same die, to directly compare a traditional flip-chip HotRod™ package and the new flip-chip Enhanced HotRod™ QFN package, demonstrating thermal, switch-node ringing, transient, efficiency and layout differences to help you decide if the Enhanced HotRod QFN package is more advantageous for your application, and if it can help improve power-supply density and performance enough to overcome any potential skepticism around adopting new technology.

Manufacturing and Rework Design Guide for MicroSiP™ Power Modules:SLIB006

With this technology, TI reaches the smallest solution size and highest levels of integration. This enables an easy-to-use power module for achieving the shortest time-to-market. As with any device package, attention must be given to the printed circuit board (PCB) layout, surface mount (SMT) assembly flow, and rework process. This white paper provides guidelines on each of these aspects, and these guidelines are achievable through normal manufacturing and rework flows.

Methods of output-voltage adjustment for DC/DC converters:SLYT777

Some systems benefit by adjusting the output voltage of one or more DC/DC converters while the converters are enabled and the system is operating. Solid-state drives, smartphones and optical modules adjust the core voltage (usually through I2C communication) to the main processor to fine-tune performance and power consumption. Other, simpler systems such as USB Type-C™ ports and lower-power microcontrollers (MCUs) use a single digital signal to adjust between two output voltages in order to adapt to power delivery demands or reduce power consumption in standby or sleep mode.

Intro to Multi-function Pins and their Applications in TI Step-down Converters:SLVAF64

This application report explains the Multi-function pin present in some of TI step-down converters (VSET/VID for TPS62864/6/8/9, VSET/MODE for TPS62865/7 and VSEL/MODE for TPS62800/1/2/6/7/8).

Layout Guidelines for Switching Power Supplies:SNVA021

Some of the main problems are loss of regulation at high output current and/or large input to output voltage differentials, excessive noise on the output and switch waveforms, and instability. Using the simple guidelines that follow will help minimize these problems.

Reduced Size, Double-Sided Layout for High-Current DC/DC Converters:SLVA963

The use of a double-sided topology for a space optimized, Clam Shell layout for step-down DC/DC converters has previously been evaluated.(1) The results showed that this technique was successful for small, SOT23 regulators delivering up to 2.5-A output current. Using both sides of the PCB gives a space efficient solution with no disadvantage in electrical or thermal performance.

Reducing Ringing Through PCB Layout Techniques:SLPA005

Designers must consider several topics when designing a printed-circuit board (PCB) layout for a dc-to-dc converter. In particular, the layout of the Power Stage components within a nonisolated synchronous buck converter requires special attention in order to optimize the overall performance of the switching function.

Constructing Your Power Supply – Layout Considerations:SLUP230

This topic addresses methods to keep circuit parasitic components from degrading the operation of your designs. Techniques to minimize the impact of parasitic inductance and capacitance of filter components and printed wire board (PWB) traces is discussed, together with a description of the impact that PWB trace resistance can have on power supply regulation and current capacity.

Space Optimized, “Clam Shell” Layout for Step-Down DC/DC Converters:SLVA818

The demand for smaller electronic products packed with more features means that the most space efficient layout is also desired. DC/DC converter ICs are available in tiny packages and it is generally the inductor which is the largest component. This paper examines the use of both sides of the PCB to achieve the most space efficient DC/DC converter layout while maintaining optimal performance.

Breakthrough Power Delivery for Space-Constrained Applications:SSZY023

For most end users, this does not mean much because they pay little attention to power supplies, even though power supplies typically consume up to half of the board space of an electronic system. Shrinking it to a fifth of its former size would mean that equipment could suddenly be much smaller and lighter-weight. Or the equipment could stay the same size and suddenly have much more space to include new high-performance functions. This is a game-changer for innovation in electronics.