Balanced Power Supply for Mixed Analog-Digitals Wall plug transformer low wattage linear power supplies   (hereinafter known as WallWarts) are available cheaply , as surplus, from various online electronics component suppliers.  Typical price is $4 to $7 for a 12VDC, 5W part.  These make great line isolation and voltage reduction platforms for all sorts of useful power supplies.  A $1 three terminal regulator and 3 capacitors will make a nice DC power supply __ Designed by Craig Taylor

BIOS interrupt performs A/D conversion 03/16/00 EDN-Design Ideas Most A/D-conversion techniques use dedicated hardware, usually a single-chip IC.  The flexible conversion technique allows you to use successive-approximation, ramp-type, or other converters by writing the appropriate control software.  The design in Figure 1 uses a PC's parallel port for interface to a DAC and a special BIOS interrupt   (INT 1CH) for the conversion process.__ Circuit Design by J Jayapandian

Bipolar Input 24-Bit A/D Converter Accepts ±2.5V Inputs Differential Input 24-Bit A/D Converter Provides Half-Scale Zero for Bipolar Input Signals Design Solutions 3 Design Notes___ Linear Technology/Analog Devices

Bridge Reversal Eliminates 1/f Noise & Offset Drift of a Low Noise, Non-Autozeroed, Bipolar Amplifier This circuit gives 14nV noise level   (or 19 effective bits) over a 10mV span.  Bridge reversal eliminates 1/f noise and offset drift of a low noise, non-autozeroed, bipolar amplifier.  The LTC2440 is a high speed 24-bit No Latency delta sigma ADC with 5ppm INL and 5μV offset.  It uses proprietary delta-sigma architecture enabling __ Linear Technology/Analog Devices App Note, Jul 8th 2010

Buffer adapts single ended signals for differential inputs 09/02/04  EDN-Design Ideas DC coupling of single-ended signals into differential-input, single-supply ADCs can be challenging.  The input signal requires level shifting from ground to VS/2 as well as single-ended-to-differential conversion.  In addition, you mu __ Designed by Randall Carver, Analog Devices Inc, Greensboro, NC

Build a complete industrial-ADC interface using a microcontroller & a sigma-delta Modulator 5-Jul-07 EDN-Design Ideas Handling both 0 to 10V and 0- to 20-mA inputs, this circuit digitizes the inputs and feeds a low-cost microcontroller__ Circuit Design by Patrick Weber and Craig Windish, Siemens Energy and Automation, Pittsburgh, PA

C# Application Controls Simple Circuit ADC 30-Oct-08 EDN-Design Ideas Control a simple, low-cost ADC with a PC's serial port__ Circuit Design by Yury Magda, Cherkassy, Ukraine

Care & Feeding of High Performance ADCs: Get All the Bits You Paid For AN71 Linear Technology This App Note describes proper techniques for applying high performance ADCs.  It describesproblems designers encounter, how to recognize ir symptoms and how to avoid m.  Topics include ground planes and grounding, supply and reference bypassing, analog input signal conditioning, sampling clock generation, signal jitter and proper handling___ Linear Technology/Analog Devices

Circuit provides precision ADC interface 08/21/03 EDN-Design Ideas Real-world measurement requires the extraction of weak signals from noisy sources.  High common-mode voltages are often present even in differential measurements.  The usual approach to this problem is to use an op amp or an instrumentation amplifier and then perform some type of lowpass-filtering to reduce the background noise level__ Circuit Design by Moshe Gerstenhaber and Charles Kitchin, Analog Devices, Wilmington, MA

Circuit provides reference for multiple ADCs 24-Jan-02 EDN-Design Ideas The achievable accuracy for systems with multiple ADCs depends directly on the reference voltages applied to the ADCs.  Medical-ultrasound-imaging systems, for example, commonly include a large number of ADCs in the system's beam-former electronics, with the ADCs usually organized in groups of 16, 24, 32, and so on__ Circuit Design by Ron Gatzke and Tanja Hofner, Maxim Integrated Products, Sunnyvale, CA

Circuits Monitor & balance large lithium-Ion batteries 09/03/07  EDN-Design Ideas Using a microcontroller's built-in ADC to measure cell voltage and temperature, this lithium-ion cell monitor equalizes the cell voltage and signals alarm conditions__ Circuit Design by Daniel Gomez-Ibanez, Woods Hole Oceanographic Institution, Woods Hole, MA

Clean Switcher Powers 16 Bit A/D Converters 07/07/94 EDN-Design Ideas The low-noise switcher in Fig 1 works much like a TV's horizontal-deflection circuit to provide clean power for a 16-bit A/D converter.  In operation, Q3 is a logic-level gate-drive MOSFET driven by the same 100-kHz square wave that clocks the A/D converter.  When Q3 turns off, the primary of T1 resonates with C3 and flies back to 25V.  Energy__ Circuit Design by Patrick Kevin Garner, Advanced Technology Systems, McLean, VA

Complete Type K Thermocouple Measurement System (SPI) with Cold Junction Compensation The LTC2484 is ideal for direct digitization of thermocouples and other low voltage output sensors.  The input has a typical offset error of 500nV (2.5μV max) offset drift of 10nV/°C and a noise level of 600nVRMS.  The only signal conditioning is a simple surge protection network.  In any thermocouple meter, the cold junction __ Linear Technology/Analog Devices App Note, Apr 8th 2010

Consideration for Successive Approximation A/D Converters AN17 A tutorial on SAR type A/D converters, this note contains detailed information on several 12-bit circuits.  Comparator, clocking, and preamplifier designs are discussed.  A final circuit gives a 12-bit conversion in 1.8µs.  Appended sections explain the basic SAR technique and explore D/A considerations. __ Linear Technology/Analog Devices

Converter Ignores Power-Supply Variation 01/05/95 EDN-Design Ideas The simple period-to-frequency converter in Fig 1 uses a dual-slope ADC (IC2) to drive a 3.5-digit display.  One medical application uses the circuit to convert the time interval between two heartbeats to a rate of number per minute.__ Circuit Design by Samuel Kerem, Infrared Fiber Systems Inc, Silver Spring, MD

Converters Yield Droop-Free S/H 11/17/11  EDN-Design Ideas (Originally published in the January 23, 1986, EDN-Design Ideas)   In low-frequency applications, many monolithic sample/hold circuits suffer a droop rate that can cause an unacceptably large output error.  The S/H circuit in Fig 1 eliminates droop error by operating two 8-bit multifunction converters back to back.  The circuit requires a 5V supply and accepts analog inputs between 0 and 2.5V (although you can scale and offset any input signal to fall within this range)__ Circuit Design by TG Barnett, The London Hospital Medical College, London, UK

Converting Light to Digits: LTC1099 Half-Flash 8-Bit A/D Converter Digitizes Photodiode Array AN33 Linear Technology This App Note describes a "Half-Flash" A/D converter, the LTC1099, being connected to a 256 element line scan photodiode array.  This technology adapts itself to handheld (i.  e.  , low power) bar code readers, as well as high resolution automated machine inspection applications. __ Linear Technology/Analog Devices

Current Input ADC Measures Voltages 08/19/99 EDN-Design Ideas A practical realization of a spread-spectrum technique lowers a µP's clock-related EMI by approximately 4 dB without the drawbacks associated with modulation (Figure 1).  The spread-spectrum technique is a popular method to reduce µP-clock-related EMI (Reference 1).  Using this method, the µP's clock frequency constantly shifts around and creates a moving target for quasipeak EMI detection.  Although this method dramatically reduces measured EMI, it has a few drawbacks.__ Circuit Design by Jim Todsen, Burr-Brown Corp, Tuscon, AZ

Current-Input ADC measures voltages EDN-Design Ideas 08/19/1999    A practical realization of a spread-spectrum technique lowers a µP's clock-related EMI by approximately 4 dB without the drawbacks associated with__ Circuit Design by Jim Todsen, Burr-Brown Corp, Tuscon, AZ

DAC & Op Amp provide variable-control voltage 12/06/01 EDN-Design Ideas Early DACs contained standard R-2R ladder networks, and produced a negative output voltage.  These early DACs, such as the MAX7837/7847 and the MAX523, require both positive and negative supply rails to accommodate their negative output.  With the transition to single-supply ICs, however, many modern DACs operate with a single supply rail and an inverted R-2R ladder network__ Circuit Design by Chad Olson, Maxim Integrated Products, Sunnyvale, CA

DC/DC converter operates from phone line 01/15/98 EDN-Design Ideas DC/DC converters for use inside the telephone handset require operation from the high-source-impedance phone line.  Additionally, the CCITT specifications call for maximum on-hook power consumption of 25 mA.  The DC/DC converter in Figure 1 is 70%-efficient at an input power of 25 mA, providing 5V at 3.4 mA.  Controlled, low-peak switch__ Circuit Design by Gary Shockey, Linear Technology Corp, Milpitas, CA

Delta Sigma ADC Bridge Measurement Techniques AN96 AN96 features several applications that demonstrate how to take full advantage of Linear Technology's delta sigma ADCs when interfacing to sensors.  In many cases, signal conditioning can be greatly simplified or eliminated completely.  This note explains where it is appropriate to use amplifiers and how to optimize amplifier gain.  Also included___ Linear Technology/Analog Devices

Design Notes 502: Matched Resistor Networks for Precision Amplifier Applications 10/03/13  EDN-Design Notes   Two-quadrant multiplying DAC utilizes octal CMOS buffer.   Some ideal op amp configurations assume that the feedback resistors exhibit perfect matching.  In practice, resistor non-idealities can affect various circuit parameters such as common mode rejection ratio (CMRR), harmonic distortion and stability.  For instance, as shown in Figure 1, a single-ended amplifier configured to level-shift a ground-referenced signal to a common mode of 2.5V needs a good CMRR.  Assuming 34dB CMRR and no input signal, this 2.5V level shifter exhibits an output offset of 50mV, which can even overwhelm the LSB and offset errors of 12-bit ADCs and drivers.__ Circuit Design by Tyler Hutchison

Differential Amp drives high-speed ADC 06/21/01 EDN-Design Ideas The schematic in Figure 1 is the discrete-element version of an A/D-converter drive circuit.  The circuit converts a single-ended input to a differential output.  The ADC's reference voltage determines the common-mode range of the differential outputs.  The circuit contains two AD9631 amplifiers—one connected in noninverting mode, and the other connected inPDF has several circuits, scroll to find this one.  -- [Chau Tran, Analog Devices Inc,Wilmington, MA]__ Circuit Design by Chau Tran

Digital position encoder does away with ADC 05/08/97 EDN-Design Ideas The position encoder in Figure 1 is a simple yet powerful circuit that converts the change in resistance of a potentiometer into a digital value without using an expensive A/D converter.  The working principle is a resistance-to-PWM converter built around the common 555 timer IC.  A change in the potentiometer's__ Circuit Design by Jose Carlos Cossio, Santander, Spain

DPPs make nonvolatile microvolt DAC 31-Oct-02 EDN-Design Ideas The availability of a seemingly limitless variety of monolithic DAC chips makes it easy to implement most digital-to-analog-conversion applications with a single off-the-shelf device.  Sometimes, an unusual set of requirements necessitates a multichip approach, however.  One example of such a requirement is the need for nonvolatility of the DAC's setting in power-up and -down cycles__ Circuit Design by Stephen Woodward, University of North Carolina, Chapel Hill, NC

Drive Delta-Sigma Analog-To-Digital Converters Cancel Input Current Errors DN368 Design Notes___ Linear Technology/Analog Devices

Drive™ ADCs Simplify Measurement of High Impedance Sensors DN379 Design Notes___ Linear Technology/Analog Devices

DSP Chip Connects to ADC over Serial Port 02/01/96 EDN-Design Ideas A multichannel ADC interface for the ADSP-21xx Series of fixed-point DSP chips uses a MAX186 low-power, eight-channel, serial, 12-bit ADC.  This ADC has many features useful for low-power data-collection applications.  The device is a complete data-acquisition system with integrated T/H and internal reference.  You can use software to configure the analog inputs for unipolar/bipolar and single-ended/differential operation__ Circuit Design by   Dhananjay Gadre, Inter-University Centre of Astronomy and Asrophysics Pune, India

Dual 8 Bit ADCs Provide Pseudo High-Resolution 10/14/00 EDN-Design Ideas Many inexpensive µC now come with several 8-bit A/D-converter channels.  However, many high-dynamic-range sensors need more than 8 bits of resolution.  The simple technique.__ Circuit Design by Douglas Butler, Imetrix Inc, Cataumet, MA 

Easy Drive Delta-Sigma Analog-To-Digital Converters Cancel Input Current Errors DN368 Design Notes___ Linear Technology/Analog Devices

Easy Drive™ ADCs Simplify Measurement of High Impedance Sensors DN379 Design Notes___ Linear Technology/Analog Devices

EEPROM Project Many projects require the use of an external EEPROM to store data.  This project will give you all the details on how to interface the Basic Stamp II with a 64K SPI Bus Serial EEPROM.  Great for those datalogging applications __ Designed by Shaun Wilson

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