Potentiometers

Information about Potentiometers

Published on August 29, 2009

Author: jaspogi

Source: authorstream.com

Content

Digitally Controlled Potentiometer : Digitally Controlled Potentiometer Slide 2: A digital potentiometer is a digitally-controlled electronic component that mimics the analog functions of a potentiometer. It is often used for trimming and scaling analog signals by microcontrollers. It is either built using an R-2R integrated circuit or a Digital-to-analog converter. Slide 3: Sometimes this device is also referred to as an RDAC, Resistive Digital-to-Analog Converter Some typical uses of digital potentiometers are in circuits requiring gain control of amplifiers (frequently instrumentation amplifiers), small-signal audio-balancing, and offset adjustment Slide 4: Limitations While quite similar to a normal potentiometer, digital potentiometers are somewhat constrained by current limits in the tens of milliamperes. Also, most, if not all digital potentiometers limit the input voltage range to the digital supply range (often 0-5VDC) Slide 5: Operation The digitally-controlled potentiometer is an integrated circuit. Polycrystalline resistors are connected in series between the RH and RL terminals and solid state switches implemented by NMOS or CMOS transistors are connected at each end of this resistor array and between the resistors. The switches are equivalent to a single pole, single throw switch. One end of all the switches are tied together and are connected to the wiper terminal. Only one switch will be closed at a time connecting a node in the series resistor array to the wiper. The resistors are polycrystalline silicon deposited on a oxide layer to insulate them from the other circuitry. Slide 6: Implementation of the Electronic Potentiometer Slide 7: Data Sheet (X9116 Digitally Controlled Potentiometer) Slide 9: Potentiometer

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