How to reduce PCB board space with the smallest device?

Engineers are often challenged to shrink a system design or pack additional functionality into the same amount of printed circuit board (PCB) space. Due to the higher PCB density in smaller systems, designers may expect increased difficulty in board wiring and board layout.

This article explores analog signal chain products that have been developed specifically to help engineers optimize board space without sacrificing the characteristics, cost, simplicity, or reliability of their systems. Its purpose is to help you understand how to leverage the benefits of these devices to develop compact, high-performance solutions for small Spaces.

1.Operational amplifiers and comparators: Flexible packaging

In analog circuits, the popularity of the op-amp is due to its versatility. Op-amp amplifiers enable high performance and high stability amplifier circuits with few passive components. This is a good place to start our discussion, as there are many performance levels and unique package options for the op amp portfolio.

In the case of Texas Instruments, the op amplifier is offered in 16 different packages, including the industry's smallest single-channel and four-channel packages, giving you multiple options to help reduce the PCB area when you need it. TI's 0.8-0.8mm leadless (X2SON) single-channel package is 13% smaller than competing smaller devices, while its 2.0-2.0mm Extra Small QFN (X2QFN) package is 7% smaller.

Consider the TLV9061 (single), TLV9062 (double), and TLV9064 (four) devices, which are low-voltage (1.8 to 5.5V) op amplifiers with rail-to-rail input and output swing capabilities. The TLV9061 is a compact single-channel op-amp in its X2SON package, 8% smaller than competing devices (Figure 1). With a 10 mhz gain bandwidth and 1.5 mv maximum offset voltage, this 5.5v op-amp provides a solution for low-voltage applications requiring a small footprint and high capacitive load drivers.

2.The smallest comparator in the industry

Similar to a standard op amp, the comparator has two inputs, one output, and two power pins. The comparator gets its name because it compares the voltage applied to its input and sets the output voltage based on the input level.

One input is the main input signal VIN and the other input is the reference signal VREF. These inputs can have both DC and AC components.

The smallest comparator in the industry, TI's TLV7081, comes in a WCSP package and measures 0.7× 0.7mm (Figure 2), 4% smaller than the competition.

The comparator runs at voltages as low as 1.7V, making it suitable for space-critical designs such as smartphones and other portable or battery-powered applications. The TLV7081 features an input voltage range independent of the supply voltage.

Thus, the comparator can be directly connected to a power source that is active even if it is not powered.

FIG. 2. The diagram shows the functional block diagram of TI TLV7081 low voltage comparator. (Source: TI)

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3. Minimal lead current sensing amplifierAs the demand for system intelligence and power efficiency continues to grow, better monitoring of critical system currents becomes increasingly important. The most common way to measure current is to detect a voltage drop across a shunt or current-detecting resistor.

4.TI's INA185 current detection amplifier comes in a small profile transistor (SOT) -563 package with a size of 1.6 x 1.6 mm (2.5 mm 2), which is 40% smaller than the closest comparable lead package (Figure 3).

Designed for space-constrained applications, the device detects voltage drops at both ends of the resistor by sensing current at common-mode voltages from -0.2 to +26 V, independent of the supply voltage.

Figure 3. This is a typical application circuit using INA185. (Source: TI)

Combining an amperometric amplifier with an integrated amperometric resistor simplifies the difficulty of resistor selection and PCB layout. The INA185 integrates a matching resistance gain network in four fixed-gain device options.

A matched resistance gain network in the amplifier achieves a maximum gain error of as little as 0.2%, which contributes to its performance over a range of temperature and process variations.

With a gain error of 0.2% and a typical response time of 2 µs, the INA185 enables rapid fault detection to prevent system damage.

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5.Data converter: Higher value per square millimeter

You can use small data converters to significantly reduce PCB footprint, increase channel density and take advantage of higher integration of other components and functions.

For example, the TI ADS7066 is a 16-bit, 8-channel Successive approximation Register (SAR) analog-to-digital converter (ADC) packaged in a single package that achieves maximum channel density and saves 54% less board space than competing devices.

The ADS7066 features an integrated capacitance-free reference voltage source and a reference voltage buffer to help reduce the size of the overall solution by reducing the number of external components. The ADS7066 has a built-in misalignment function to improve accuracy under a wide range of operating conditions.

The ADS7066's eight channels can be configured separately for analog input, digital input, or digital output, thus achieving a smaller system size and simplifying circuit design for mixed signal feedback and digital control.

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6.conclusion

Thanks to its packaging and process technology, TI is able to offer the industry's smallest equipment across multiple product portfolios.

The company's packages include traditional ceramic and leaded options as well as advanced chip-level packages -- Tead Flat Leadless (QFN), Chip-on-chip (WCSP) or core-sized ball grid arrays (DSBGA) use fine-pitch wire bonding and flip-chip interconnection, and are available in SiP, modular, stacked and recessed core-based formats.