Isolated RS485 Transceiver with Power in One Small Package
with Jeff Marvin, Design Center Manager

The benefits of galvanic isolation extend beyond safety and protection from dangerous voltages to provide error-free communication in the presence of high edge rate transients, noise and high common mode voltage that would otherwise render a non-isolated network inoperative.

High Current LED Driver with Three-State Control
with Walker Bai, Applications Engineer Section Leader, Power Products

There are many LED drivers on the market for low current LEDs and many others for high current LEDs. Low current LEDs are 20mA to 100mA LEDs. High current ones are 100mA to ~1A. But how many 20A LED drivers do you know? How about 40A? Not many. How about super fast µs rise time between 0A and 20A or between any two current levels? Not heard of. Not until now.

775 Nanovolt Noise Measurement for a Low Noise Voltage Reference
with Jim Williams, Staff Scientist

Frequently, voltage reference stability and noise define measurement limits in instrumentation systems. In particular, reference noise often sets stable resolution limits. Reference voltages have decreased with the continuing drop in system power supply voltages, making reference noise increasingly important. The compressed signal processing range mandates a commensurate reduction in reference noise to maintain resolution. Noise ultimately translates into quantization uncertainty in A-to-D converters, introducing jitter in applications such as scales, inertial navigation systems, infrared thermography, DVMs and medical imaging apparatus.

IC Current Sources
with Robert Dobkin, Vice President, Engineering
and Chief Technical Officer

Current sources have been a well known but theoretical circuit component. Unlike voltage sources, a 0.01% accurate 2-terminal current source has been an elusive component that is not easily available and difficult to design. With the introduction of the LT3092, the current source as a drop-in component becomes a reality.

Low Noise µModule DC/DC Converters Simplify EMI Design
with David Ng, Manager - Module Development

EMI can be hard to fix. Linear Technology’s new line of low noise uModule DC/DC converters are not only easy to use, they are quiet enough to ease EMI problems in your design from the very start.

Measuring Switching Regulator Noise
with Jim Williams, Staff Scientist

The universal application of switching regulators, combined with the powered systems potential for supply noise sensitivity, mandates the need for a reliable noise measurement technique. Actually, switching regulator "noise" isn't really noise at all, but coherent, high frequency residue directly related to the regulators switching. This residue, composed of fundamental switching frequency ripple and wideband harmonic, is the measurand.

The Simple Way to Match to a High-Speed ADC Input
with Todd Nelson, Manager - Module Development

High-speed, high-resolution ADCs are critical components in communications and instrumentation applications. The interface between the final amplifier of the signal chain and the input pins of the ADC is challenging and time-consuming. Yet it is critical to the performance of the entire system. Traditionally, this requires impedance matching, developing an anti-alias filter and multiple iterations of the board layout to get everything right.

Small Size & Very High Efficiency Buck-Boost Converter
with Henry Zhang, Applications Engineering Manager - Power Products

Many applications such as battery-powered supply have a wide input voltage that can be lower or higher than the regulated output voltage. The conventional solutions, such as flyback, Sepic or a 2-stage supply are usually complicated and inefficient.

Building Robust Serial Links with Virtex-5 FPGAs and uModule DC/DC Regulators

Designing and implementing low noise power supplies suitable for powering high speed serial interfaces such as Xilinx Rocket I/O requires significant design time and expertise. Low noise uModule DC/DC regulators from Linear Technology offer a simple, low noise, space saving way to power a high speed serial interface.

Reduce Digital Feedback in Data Conversion Systems
with Clarence Mayott, Applications Engineer - High Speed Data Converter Products

Linear’s newest high-speed ADC family achieves 1/3rd the power consumption of existing solutions without compromising AC performance. Operating from a low 1.8V supply, the 14-bit, 125Msps LTC2261 dissipates 125mW while maintaining 73.4dB SNR and 85dBc SFDR. Digital outputs can be configured as DDR CMOS, DDR LVDS or standard CMOS for minimizing FPGA pin count. An optional alternate bit polarity mode is provided to reduce the effects of digital feedback.

Simple Ways to Measure Current
with Jon Munson, Applications Engineer - Amplifier Products

Measuring current is one of the basic requirements in many electronic systems; whether for precise control or simple protection of circuit elements. A family of new devices from Linear Technology has been produced to greatly simplify the measurement of DC or AC current. Using only external resistors, each small device can be tailored to specific needs and used in a wide range of operating conditions.

How to Design a Simple Isolated Power Supply
with Mike Negrete, Design Engineer - Power Products

Isolated power supplies are needed in a wide variety of applications. Galvanic isolation is achieved by isolating two or more circuits using a transformer or optocoupler, and is desirable for many reasons: safety, noise immunity, circuit protection, etc.

Voltage vs. Current Mode Control Current Sharing in a PolyPhase DC/DC Converter
with Henry Zhang, Applications Engineering Manager - Power Products

Current sharing performance is critical for PolyPhase® DC/DC converter to balance the thermal stress and properly size the power components. The PolyPhase converter can be controlled by either voltage or current mode control scheme. With voltage mode control, the active current sharing is achieved with a complicated external current sharing loop, which is usually slower than the inner voltage feedback loop. With current mode control, such as implemented in the LTC3731 or LTC3850, the current sharing can be implemented very easily with its fast current loop.

Paralleling Amplifiers and Transmission Lines for Driving Capacitive Loads Fast
with Glen Brisebois, Applications Engineer Signal - Conditioning Products


Certain video and other technologies require driving planar conductive surfaces fast. Unfortunately, the surfaces can have high capacitance, which means that driving them fast takes high currents. This complicates the amplifier design but the situation extends beyond just the amplifier. Between the amplifier and the capacitive load, there is necessarily some length of transmission line.

How to Design a Complex Switching Regulator as Simple as a Linear Regulator
with Eddie Beville, Design Manager - DC/DC uModule Regulators


There is an alternative solution when deciding between a step-down switching regulator and a linear regulator. Switching regulators dissipate less heat than linear regulators especially when the input voltage is much higher than the output voltage or the output load current is relative high. On the other hand, linear regulators are very simple and don’t require inductors. What if there was a switching regulator circuit could be simplified and fitted inside a surface mount package and the complete solution became as simple as a regulator’s circuit? No inductors, no MOSFETs, no difficult calculations for compensation circuitry. On paper, it is a simple square box with a few resistors and capacitors. On a PCB, it is also a simple square box with a few resistors and capacitors.

Direct Paralleling, High Power Density LDO
with Robert Dobkin, Vice President, Engineering
and Chief Technical Officer

The LT3080 is a new architecture for linear regulators. It provides better regulation, a simple output adjustment with a single resistor where the output can be adjusted down to zero. Also, this architecture allows easy paralleling of regulators for “no heatsink” operation in an all surfacemount applications. The LT3080 circuit operation and applications for paralleling, spreading the heat, general purpose power supplies and current sources will be shown.

Low Noise, High Voltage DC/DC Converters
with Jim Williams, Staff Scientist

Photomultipliers (PMT), avalanche photodiodes (APD), ultrasonic transducers, capacitance microphones, radiation detectors and similar devices require high voltage, low current bias. Additionally, the high voltage must be pristinely free of noise; well under a millivolt is a common requirement with a few hundred microvolts sometimes necessary. Circuits featuring outputs from 200V to 1000V with output noise below 100µV measured in a 100MHz bandwidth are detailed in this video. Special techniques enable this performance, most notably power stages optimized to minimize high frequency harmonic content. An additional aid to achieving low noise is that load currents rarely exceed 5mA. This freedom permits output filtering methods that are usually impractical. A lab-based circuit noise measurement demonstration concludes the presentation.

How to Make a Thermocouple Meter with the LTC2492
with Mark Thoren, Applications Engineering Manager - Mixed Signal Products

Thermocouples are perhaps the most common temperature sensor in use. And while they are extremely simple and rugged, the output is very small - tens of microvolts per degree Celsius. Traditionally, thermocouple measurement circuits use a cold junction compensation circuit to drive the thermocouple negative terminal and a low offset amplifier with enough gain to use the entire input span of a 12- or 16-bit ADC. Linear Technology’s LTC2492 greatly simplifies thermocouple instrument design. A simple filter and protection circuit is all that is required to build a rugged, ready-to-use meter. Some software tricks take care of cold junction compensation and the thermocouple’s non-linear output.