Taking a “Series First” Approach to Op Amp Design

When I first visited a BBQ restaurant in Texas, I was so surprised by the variety of meats on the menu that I didn’t know which one to choose. But luckily, the grill offered a three-meat platter so I could try different kinds of meat.

By Hayden Hast C Systems Engineer

When I first visited a BBQ restaurant in Texas, I was so surprised by the variety of meats on the menu that I didn’t know which one to choose. But luckily, the grill offered a three-meat platter so I could try different kinds of meat.

In fact, as a design engineer looking for an operational amplifier (op amp), you too have many options. Plus, with today’s ever-shorter production cycles, you need to make quick decisions. Choosing the wrong op amp can cost time and money.

TI’s extensive product portfolio consists of 48 unique amplifiers (including the new TLV9001, TLV9052, TLV9064) offered in 16 different packages, including the industry’s smallest single- and quad-channel packages. In this technical article, you’ll learn how this new family of op amps can meet a variety of project needs, reduce printed circuit board (PCB) space, and offer multiple bandwidth options to give your signal chain more gain.

Our broad and diverse product portfolio can help you choose the exact number of channels, speed, and determine your system needs.

Diversify design functions 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 voltages. Additionally, its similarly low-resistance output impedance minimizes stability issues.

Figure 1: Amplifier Family Comparison

However, each sub-series offers unique performance advantages. For example, if you initially used the TLV9002 in a single-supply low-side, unidirectional current-sensing solution with an output swing to GND circuit to sense motor current, but later, to handle large motor current transients, determined that a more High gain and faster slew rate, then 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.

Packaging flexibility

Figure 2 details the details of the various packaging options. The “Industry Standard” column determines whether the package is available from another supplier as an option for a second purchase. The Shutdown column highlights footprints with shutdown capabilities. The shutdown function helps reduce overall energy consumption.

While most of the small package options are Quad Flat No-Lead (QFN) packages, the package options I’ve highlighted are not of the above type. The Dual, Small Outline Transistor (SOT)-23-thin package features a single-channel SOT-23 package body, but it has 8 pins instead of the traditional 5 or 6 pins. This is a very good choice for those larger leaded packages such as Small Outline Integrated Circuit (SOIC), Thin Small Outline Package (TSSOP) or Very Thin Small Outline Package (VSSOP). Dual layout techniques are also available for multi-sourcing 8-pin SOT-23 and traditional leaded packages. For more details, read the Analog Design Journal article, “Secondary Purchasing 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

The three amplifier sub-series are housed in the industry’s smallest single- and quad-channel packages. TI’s single-channel 0.8mm x 0.8mm ultra-small leadless (X2SON) package is 13% smaller than comparable small form factor devices, and its 2.0mm x 2.0mm ultra-small QFN (X2QFN) package is 7% smaller %. These packages, combined with the dual 1.0mm x 1.5mm X2QFN package, offer a variety of options to help you reduce PCB area. You can see these 3 packages on the right side of Figure 3.


Figure 3: Progressive implementation of smaller packages

Because of the small pitch, manufacturing technology may limit the use of ultra-small QFN packages, so TI also offers a variety of 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.

Summarize

Some people say that too many choices can lead to nowhere to start. But I think whether it’s deciding what grill to eat in Texas or a design engineer choosing an amp, of course the more choices the better. When you next start designing, you can choose from the following family of op amps: Available in three different performance levels; one of 16 unique package options; available in the industry’s smallest single- and quad-channel packages and available when you need it Save PCB area.

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