by Benabadji Noureddine @ edn.com:
Several previously published Design Ideas and appnotes [1-4] show how to use many pushbuttons with a minimum number of inputs. They require an RC circuit where the timing can be measured to identify which pushbutton has been pressed, or an ADC input, with resistors forming a divider for each pushbutton pressed.
The following Design Idea shows another simple way to use up to 15 pushbuttons with only one I/O. The microcontroller chosen must contain an internal comparator with selectable values for the internal voltage reference VREF.
Monitor 15 contacts with one PIC input - [Link]
This compact Fremont subsystem reference design accurately measures low voltage, 0 to 100mV, single-ended analog signals with a high-accuracy, 16-bit analog front end (AFE) complete with an isolated data path. The design optimizes the functions of an ultra-precision low-noise buffer (MAX9632); a highly accurate ADC(MAX11100); an ultra-high-precision 4.096V voltage reference (MAX6126); a 600VRMS monolithic data isolator (MAX14850); and low-dropout (LDO) regulators providing regulated +6V, +5V, and -5V power rails (MAX1659 and MAX1735).This one-of-a-kind AFE solution works in many applications requiring low-voltage input, high impedance, and high-accuracy analog-to-digital conversion.
Maxim Fremont: 16-Bit, High-Accuracy, 0 to 100mV Input, Isolated Analog Front-End (AFE) - [Link]
The LTC2946 is a high or low side charge, power and energy monitor for DC supply rails in the 0V to 100V range. An integrated ±0.4% accurate, 12-bit ADC and external precision time base (crystal or clock) enables measurement accuracy better than ±0.6% for current and charge, and ±1% for power and energy. A ±5% accurate internal time base substitutes in the absence of an external one. All digital readings, including minimums and maximums of voltage, current and power, are stored in registers accessible by an I²C/SMBus interface. The part’s wide operating range makes it ideal for monitoring board energy consumption in blade servers, telecom, solar and industrial equipment, and advanced mezzanine cards (AMC).
LTC2946 – Wide Range I2C Power, Charge and Energy Monitor - [Link]
The Santa Fe (MAXREFDES5#) reference design is a 16-bit high-accuracy industrial analog front end (AFE) that accepts -10V to +10V, 0 to 10V, and 4–20mA current loop signals with isolated power and data integrated into a small form factor. The Santa Fe design integrates low-noise/high-impedance analog buffers (MAX9632); a highly accurate ADC with on-chip attenuation (MAX1301); an ultra-high precision 4.096V voltage reference (MAX6126); 600VRMS data isolation (MAX14850); and isolated/regulated +12V, -12V, and 5V power rails (MAX256/MAX1659). This AFE solution can be used in any application that needs high-accuracy ADC, and targets industrial sensor, automation, process control, PLC, and medical applications.
SANTA FE (MAXREFDES5#): 16-BIT HIGH ACCURACY MULTI-INPUT ISOLATED ANALOG FRONT END (AFE) - [Link]
Ondřej Karas of DoItWireless writes:
We described simple method, how to drive modellers servo. Today, we are going to try to drive this servo from potentiometer connected to TR module ADC. It is reaction to forum thread where is discussion about airplane model control possibility.
Wireless servo controller II - [Link]
In this episode Shahriar explores the world of Delta-Sigma modulators with emphasis on a Delta-Sigma Analog to Digital Converter (ADC). The basic concepts of analog to digital conversion is presented, particularly with respect to quantization noise spectral shape and power density. Next, oversampling ADCs are presented to demonstrate the possibility of increasing SQNR (ENOB) through manipulation of quantization noise spectrum.
Due to the practical limitations of high oversampling ratios, delta-sigma modulations is explored. The principle operation behind delta-sigma ADCs is presented with detailed explanation on noise shaping, filtering and decimation. The signal and noise transfer functions for a 1st order and 2nd order delta-sigma ADC are derived. Finally, as a practical example, a 2nd order delta-sigma ADC based on a 1-bit quantizer is presented. The ADC uses two Miller integrator op-amps, one comparator and a D-Type flip-flop. The complete measurement of this delta-sigma ADC is presented. The impact of over sampling ration, op-amp linearity and input signal bandwidth is presented. The slides for this video can be downloaded from The Signal Path website.
Theory, Design and Characterization of Delta-Sigma Analog to Digital Converters - [Link]
by Avago Technologies:
Analog isolation is still widely used in motor drives, power monitoring, etc whereby applications typically use inexpensive analog voltage control for speed, intensity or other adjustments.
The HCNR201/200 analog optocoupler is commonly added to isolate the analog signal in the front end module of an application circuitry. The optocoupler will be placed between the analog input and the A/D converter to provide isolation of the analog input from the mixed signal ADC and other digital circuitries. The HCNR201/200 is an excellent solution for many of the analog isolation problems.
Fast analog isolation with linear optocouplers - [Link]
An SMPS application using PIC16F785 from Microchip. [via]
In this application note, we will examine a typical buck topology intelligent SMPS design using the PIC16F785.
The design presented here shows an alternative single-chip approach to adding intelligence to SMPS designs. The basic design is really unchanged. There are current and voltage feedback loops, a counter-based PWM is used to generate the reference voltage to the voltage loop, and the microcontroller uses the reference voltage to modify the operation of the system in response to conditions sensed through the ADC.
App note: Switching power supply design with the PIC16F785 - [Link]
by prem_ranjan @ open-electronics.org:
We have designed an Oscilloscope using PC and Arduino Board. The signal is first of all fed to the Arduino Board where the analog signal is converted to a digital signal by the ADC which is then serially outputted to the PC and is read by the MATLAB software via the COM ports. Here the signal is read in the form of digital data but then is converted to analog one by using the resolution of the ADC used by the Arduino Board. The MATLAB software was then used to plot the signals.
A PC and an Arduino: here’s your DIY Oscilloscope - [Link]
TMP75B 1.8-V Digital Temperature Sensor with Two-Wire Interface and Alert. by ti.com:
The TMP75B is an integrated digital temperature sensor with a 12-bit analog-to-digital converter (ADC) that can operate at a 1.8-V supply, and is pin and register compatible with the industry-standard LM75 and TMP75. This device is available in an SOIC-8 package and requires no external components to sense the temperature. The TMP75B is capable of reading temperatures with a resolution of 0.0625°C and is specified over a temperature range of –55°C to +125°C.
The TMP75B features SMBus and two-wire interface compatibility, and allows up to eight devices on the same bus with the SMBus overtemperature alert function. The programmable temperature limits and the ALERT pin allow the sensor to operate as a stand-alone thermostat, or an overtemperature alarm for power throttling or system shutdown.
TMP75B – 1.8V Capable Digital Temperature Sensor - [Link]