The benefits of 4-20mA current loop format in process control systems are 2-wire sensor operation, long cable runs, and noise immunity. The voltages for the loop can be ranging from 12VDC to 40VDC and are inherently nonratiometric to the output signal. The MAX1452 low current consumption allows the system to operate from loop power with a simple 4-20mA circuit drives. Here’s the circuit diagram:
The MAX1452 is equipped with five 16-bit internal calibration registers that can be loaded from the serial digital interface or from EEPROM. You can get more information about MAX1452 at http://datasheets.maxim-ic.com/en/ds/MAX1452.pdf .
This application note describe about ADC cycle latency, ADC latency time, and the delta-sigma analog-to-digital converter (ADC). The theory about ADC cycle latency, ADC latency time, and the delta-sigma analog-to-digital converter (ADC) are presented in detail after introduction.
The main topic is divided into 2 sections : ADC cycle latency and ADC latency time. The section ADC cycle latency contains about cycle latency for ADC. The description about latency time for ADC is explained in section ADC latency time.
Download/view the application note.
Many appliances such as information personal digital assistants (PDAs) and instrumentation and control applications are use touch-screen interfaces. This is a application notes of using resistive touch screens for human/machine interface. This application notes describes about how to convert the analog inputs into usable digital data, the basics of how resistive touch screens work, resistive touch screens, resistive touch-screen controllers, and touch-screen acquisition flowchart.
This application note is divided into sections as follows :
-Introduction
-Resistive touch screens
-Resistive touch-screen controllers
-Single-ended configuration
-Differential configuration
-Touch-screen settling time
-Difference between single-ended and differential modes
-Touch-screen acquisition flowchart
-Data-averaging algorithm
Download/view the application note.
The signal-processing block of thermocouple is sensitive to EMI, just like other low-level circuitry. It’s wires are often exposed to EMI. It will increase undermines the accuracy of the acquired temperature data and uncertainty in the received signal. To solve this problem, usually we use special thermocouple cable but it will expensive and if we replace with another cable, the resulting situation will be difficult to diagnose. Therefor, we can use digital transmission to solve the problem. Here is the circuit :
The circuit will minimize noise by moving the controlling circuitry and adding a remote board with local intelligence near the sensing point. A local pulse-sequence generator (IC3 and IC2) drives the MAX6675/MAX6674′s SPI interface. Four characters per second: 1 stop bit, 1 start bit, and 11 data bits (13 data bits for the MAX6675) and a train of asynchronous serial characters at 4800 bauds are generated by the MAX6674/MAX6675 that is forced by IC2 and IC3.
The 11 data bits for the MAX6674 are 1 bit to warn of an open thermocouple and 10 straight-binary data bits for temperature (MSB first). 12 data bits and 1 bit are provided by the MAX6675 for the alarm. [Source: maxim-ic.com]
