Monday, April 03, 2017

Digital Potentiometer - AD5242 - Analog Devices

AD5241 and AD5242 provide a single-/dual-channel, 256-position, digitally controlled variable resistor (VR) device. They have 2-Wire I2C Compatible Digital Interface.

Digital Potentiometer - AD5242 - Analog Devices

They are Analog Semiconductor Replacements for Electromechanical Devices like potentiometer, trimmer or variable resistor.

The Advantage of the latter is low cost and easy to configure and use. The Advantage of the Digital Version is "No moving Parts". hence not limited to things like "10000 operations". Another clear advantage is precision and vibration resistant.

See an Application of this Digipot in a TinyOS hardware magnetometer.. 

Digital Potentiometer AD5242 Magnetometer Application

The temperature stability of 30 ppm/°C and low noise settings is also achieved with SiCr thin film resistor technology. They range from 10K, 100K and 1M Ω End-to-End Terminal Resistances.

Digipots are not for high currents or power, even high voltage and very low resistance values are not for these devices. These are signal control devices. Use it for analog circuits and instrumentation and signal control too.

MAX5160 Digital Potentiometers - Maxim

They are linear-taper digital potentiometers perform the same function as a mechanical potentiometer or a variable resistor.

MAX5160 Digital Potentiometers - Maxim

Three resistance values are available for each part type: 50kΩ,100kΩ, and 200kΩ. A nominal resistor temperature coefficient of 50ppm/°C end-to-end and only 5ppm/°C ratiometric.

MAX5160 Digital Potentiometers - Maxim

This has 32 Tap Positions, 400Ω Wiper Resistance, 3-Wire Serial Data Input . Power-On Reset: Wiper Goes to Midscale (position 16).

See an application circuit of this chip - A solid-state industrial potentiometer simulates an equivalent mechanical potentiometer, and fits in the same space. 

Industrial 0V to +10V Digital Potentiometer

The key to this circuit is a low-power digital potentiometer IC, 100kΩ version (U3). Configured as a voltage divider, this IC provides an output of 32 discrete voltage steps between its minimum and maximum settings (0V and 5V). A low-power linear regulator (U1) provides a +5V supply rail for U2, U3, and a resistor ladder internal to U3 (whose maximum rating is +5V).

Saturday, April 01, 2017

AD8436 - Low Cost RMS to DC Convertor

This chip from Analog Devices  computes a precise dc equivalent of the rms value ac waveforms, including complex patterns such as those generated by switchmode power supplies and triacs.

AD8436 - Low Cost RMS to DC Convertor

There is an evaluation board available to study its performance.

AD8436 - Low Cost RMS to DC Convertor

Delivers true RMS or average rectified value of an AC input and Fast is settling at all input levels.It is an Accurate conversion with crest factors up to 10.

AD8436 - Low Cost RMS to DC Convertor

Typical application for frequencies as low as power line, and above. The recommended averaging, crest factor and LPF capacitor values are 10 μF, 0.1 μF and 3.3 μF.

Other Features
  • Accuracy: ±10 µV ± 0.5% of reading 
  • 100 µV rms to 3 V rms (8.5 V p-p) full-scale input
  • 1 MHz for -3 dB (300 mV) 
  • 65 kHz for additional 1% error 
  • Zero converter dc output offset 
  • Low power: 300 µA typical at ±2.4 V