Taking a “family-first” approach to op amp design

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Taking a “family-first” approach to op amp design [Copy link]

When I first visited a Texas barbecue restaurant, I was so surprised by the variety of meats on the menu that I didn't know which one to choose. Fortunately, the restaurant offered a platter of three meats so I could try different types of meat.
　　As a design engineer looking for an operational amplifier (op amp), you have many choices. Plus, with today's ever-shrinking production cycles, you need to make decisions quickly. Choosing the wrong op amp can cost time and money.
　　TI's extensive portfolio consists of 48 unique amplifiers (including the new TLV9001, TLV9052, TLV9064) in 16 different packages, including the industry's smallest single- and quad-channel packages. In this technical article, you'll learn how this new op amp family can meet a variety of project needs, reduce printed circuit board (PCB) space, and provide multiple bandwidth options to provide more gain in your signal chain.
　　Our rich and diverse portfolio can help you choose the right number of channels, speed, and determine your system needs.
　　Diversify your design capabilities through outstanding product performance
　　Figure 1 provides an overview of the full device family, with similarities highlighted at the top. The three sub-families are interchangeable because they use the same supply voltage, input and output voltage ranges, and offset voltage. In addition, their similar low-resistance output impedance minimizes stability issues.
　　

　　Figure 1: Amplifier Family Comparison
　　However, each sub-family offers unique performance advantages. For example, if you initially use the TLV9002 in a single-supply low-side, unidirectional current sensing solution with output swing to GND circuitry for motor current sensing, but later determine that higher gain and faster slew rates are required to handle large motor current transients, you can easily switch to the higher bandwidth, pin-to-pin compatible TLV9052 without redesigning. This is possible because each sub-family has the same 16 package options covering all three channel configurations.
　　

　　Figure 2 details the various packaging options. The Industry Standard column identifies whether the package is available from other suppliers as a second-source option. The Shutdown column highlights packages that have a shutdown feature. The shutdown feature helps reduce overall power consumption. While most
　　of the small package options are quad flat no-lead (QFN) packages, the package options I highlight are not of that type. The dual, small-outline transistor (SOT)-23-thin package uses the body of a single SOT-23 package, but it has eight pins instead of the traditional five or six. This is a great alternative to larger leaded packages such as small-outline integrated circuits (SOICs), thin small-outline packages (TSSOPs), or very thin small-outline packages (VSSOPs). Dual layout techniques are also available to multi-source the 8-pin SOT-23 and traditional leaded packages. For more details, read the Analog Design Journal article, “Second-Sourcing Options for Small-Package Amplifiers.” However, if you want to minimize PCB space, I recommend the QFN package option.
　

　　Figure 2: Amplifier family package options
　　Breakthrough in size
　　These three amplifier subfamilies feature the industry’s smallest single- and quad-channel packages. TI’s single-channel 0.8mm x 0.8mm Extra Small Outline No-Lead (X2SON) package is 13% smaller than similar small-footprint devices, and its 2.0mm x 2.0mm Extra Small QFN (X2QFN) package is 7% smaller. These packages, along with the dual-channel 1.0mm x 1.5mm X2QFN package, provide a variety of options to help you reduce PCB area. You can see the three packages on the right side of Figure 3.
　　Take a “family-first” approach to op amp design
　　Figure 3: Progressively smaller packages
　　Since manufacturing techniques may limit the use of extra small QFN packages due to smaller pitches, TI also offers several small package options with different pitches. The application report, “Designing and manufacturing with TI’s X2SON packages,” provides layout and routing guidelines for these packages.
　　Conclusion
　　Some say having too many options can be overwhelming. But I think, whether it's deciding what barbecue to eat in Texas or a design engineer choosing an amplifier, the more choices the better. The next time you start a design, you can choose from a family of op amps that offer three different performance levels; one of 16 unique package options; and the industry's smallest single and quad packages to save PCB area when you need it.