Analog Diablog is the place to comment on the articles found in Analog Dialogue (or those that you'd like to see). It can also be used as a discussion forum on products, applications, technology, and techniques for analog, digital, and mixed-signal processing using Analog Devices components.
Resistive touch screens conventionally fill a market niche where only a single touch is required, high resolution is paramount, a stylus facilitates specific functionality, or users must wear gloves. This article offers a new dual-touch concept using an AD7879 resistive touch-screen controller to detect the most common two-finger gestures (zoom, pinch, and rotation) using inexpensive resistive touch screens.
Typical low-power systems operate with a Li-Ion battery whose output varies from 4.2 V to 3 V, while the ICs require 0.8 V, 1.8 V, 2.5 V, and 2.8 V. A simple way to reduce the voltage is to use an LDO, but power not delivered to the load is lost as heat, making LDOs inefficient when VIN is much greater than VOUT. Switching converters store energy in a magnetic field, enabling high-efficiency regulation.
In Difference Amplifier Forms Heart of Precision Current Source, published in Analog Dialogue in September 2009, the AD8276 unity-gain difference amplifier and AD8603 micropower op amp were used to implement a precision current source. This article shows how the circuit can be simplified for use in low-cost, low-current applications—achieving ±1.5% accuracy from –40°C to +85°C.
This article describes the challenges that engineers face when designing switches and multiplexers into hostile environments, and suggests solutions that the circuit designer can use to protect vulnerable parts. It also introduces some new integrated switches and multiplexers that provide increased overvoltage protection, latch-up immunity, and fault protection to deal with common stress conditions.
