Design of Digital Circuit Potentiometer AD5272 Application Circuit System

Photocoupler

Through the research and analysis of digital potentiometer chips, combined with the needs of low-cost market, build hardware and software platforms, build mixed-signal system circuits, and expand the application field and scope of digital potentiometers. The working principle, characteristics, classification and wide application of digital potentiometer are described. The advantages of digital potentiometer compared with mechanical potentiometer are described. The internal circuit structure of digital potentiometer AD5272 is also described. On this basis, further Digital potentiometer AD5272 application circuit system design. The results show that the performance and application of the digital potentiometer are fully demonstrated under the premise of low cost, and the digital potentiometer is verified to be more economical and practical.

Digital potentiometers are digital-analog mixed-signal processing integrated circuits fabricated in CMOS technology, also known as digitally-programmable resistors. The use of the numerical control method to adjust the resistance value, the use of polysilicon or thin film resistor material, which has the characteristics of flexible use, high adjustment accuracy, no contact, low noise. At the same time, it has small volume, saves printed board space, is easy to install, is not easy to be stained, anti-vibration, anti-interference, long life, and is not susceptible to environmental temperature. Based on the above, digital potentiometers have been widely used in various fields such as healthcare equipment, instrumentation, communication equipment, industrial control, household appliances, and digital products.

1 Introduction to digital potentiometer

1.1 Main features

Digital potentiometers are a promising new device. Compared with mechanical potentiometers, there are many advantages, see Table 1, so mechanical potentiometers can be replaced in many fields. In any field where parameter adjustment, calibration or control is performed with a resistor, a digital potentiometer can be used to form a programmable analog circuit for adjustment. In addition to the above features, its characteristics are:

1) Digital-to-analog mixed-signal products, a special form of digital-to-analog converter (DAC) consisting of digital control circuits, memories, and RDAC circuits. Among them, RDAC is an important part of the digital potentiometer, composed of a resistor digital-to-analog converter circuit.

2) The resolution is related to the number of internal RDAC bits (see Table 2). The more RDAC bits, the higher the resolution;

3) It has its own control interface, memory and resistance system, and has a non-volatile memory EEPROM inside, which can be read and written by the user, and its resistance value is programmed through the software control interface;

4) Digital control and adjustment of resistance, voltage or current in analog circuits can be realized by digital potentiometer;

5) Allow several digital potentiometers to be serial, parallel or hybrid;

6) Due to the influence of the production process, the total resistance is poor, generally 15% to 30% deviation;

7) Low voltage, low power consumption, ultra-small size, wide operating temperature range.

1.2 main parameters

1) The difference between the highest power supply voltage range and the lowest operating voltage. This range is generally 2.5 to 5.5 V.

2) The terminal voltage is applied to the high-side and low-side voltages. Generally, the terminal voltage is in the range of 0 to VCC.

3) The ratio of the minimum resistance value to the total resistance that can be resolved by resolution, expressed as a percentage.

4) The number of taps is used to adjust the number of terminals of the resistor value. For example, if n bit, the number of taps is .

5) Nominal resistance tolerance The actual resistance deviation value is a percentage of the ideal value.

6) Sliding terminal resistance internal analog switch on-resistance, the resistance value is related to internal circuit structure and terminal voltage.

7) Bandwidth Bandwidth Referring to bandwidth, also known as passband, an indicator describing the frequency response. There are three representations: -3 dB bandwidth, unity gain bandwidth, and gain bandwidth product.

8) Interface refers to the circuit connected to the microprocessor or microcontroller.

9) When the settling time control code changes from the minimum value to the maximum value, the time required for the digital potentiometer to stabilize is generally a few microseconds.

10) Resistive noise voltage The random noise generated by the internal resistance in a certain frequency bandwidth, the unit is μV/Hz.

This website tries to open micro- and small-enterprise business advertising business; maintenance point recommended items. The fee is affordable and effective! Welcome to contact in QQ or email!

Why do you want to do online advertising contact?