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Combinational logic circuits
Published in David Crecraft, David Gorham, electronics, 2018
The original ‘standard’ TTL configuration had a propagation delay of around 9 ns. Adding a Schottky diode to this basic circuit configuration produced single gates with propagation delays as short as 3 ns. However this Schottky TTL (STTL, with device codes such as 74S00) dissipates much more power than standard TTL. Low-power Schottky TTL (LSTTL) dissipates only one-fifth of the power of standard TTL and about a tenth of the power of STTL but still achieves a typical propagation delay less than 10 ns per gate. Further developments have led to other new TTL families, such as advanced low-power Schottky (ALS) with even better speed and power figures, but these are, at present, rather more expensive.
Digital Logic Families
Published in Jerry C. Whitaker, Microelectronics, 2018
The minus sign in the fanout computations arises because both input and output current reference directions are defined into the device. Most parts in the standard TTL family have a fanout of 10 when driving other standard TTL circuits. Buffer circuits with increased output current capability are available for applications such as clock signals that must drive an unusually large number of inputs. TTL families other than standard TTL have different input and output current specifications; fanout computations should be performed whenever parts from different families are mixed.
Hardware for automation
Published in Benny Raphael, Construction and Building Automation, 2023
UART is a piece of hardware used to implement serial communication (including RS232). The UART chip converts the data into serial form for transmission through the serial port. TTL stands for transistor-to-transistor logic. It is similar to RS232, but the voltage level is lower; 0–5 V is used. 0 V stands for bit value of 0, and 5 V stands for bit value of 1. Note that it does not use negative voltage, unlike in RS232.
Ideas for Improving the Digital Design Lab
Published in IETE Journal of Education, 2023
Typical experiments in combinational design in a “Digital Lab” include (i) Designing and demonstrating the working of arithmetic circuits such as full-adder or ripple-carry adder (ii) Designing simple random logic from a specification e.g. a 3-input majority voter or code converter. The student is expected to be familiar with Karnaugh maps [10] and the process of deriving the minimum sum-of-products expression from a Karnaugh map. The student should know the concept of universal logic blocks which can be used to build any digital logic circuit. NAND gates, NOR gates and two- to −1 multiplexers are examples of universal logic blocks. Combination of XOR and AND gates can also be used to realize any digital logic. Familiarity with some combinational blocks such as decoders, encoders, multiplexers, demultiplexers, ALU, etc. is also useful. Circuits from the TTL logic family are used in most labs. The student must know the concepts of active high and active low inputs, the high impedance state, the don't care input, and unknown output. In a TTL circuit, leaving an input unconnected would be tantamount to connecting the input to a logic 1.
Harmonic performance analysis of a wind driven micro grid inverter
Published in International Journal of Ambient Energy, 2022
Sri Devi Ravanan, Ezhilarasi Arivukannu, Suresh Padmanabhan Thankappan, Ramaswamy Muthiah
The effort extends to test the methodology through a suitable prototype where it involves the use of the ATmega microcontroller for generating the pulses to turn ON the MOSFET switches in both the SEPIC and the micro-grid inverter. The ATmega 8A belongs to the class of a low power CMOS 8-bit microcontroller based on the AR RISC architecture. It takes an 8k bytes of in-system self-programmable flash with 512 K bytes EEPROM, 1 K byte internal SRAM, three timers and a 10-bit 6 channel A/D converter. It executes powerful instruction in a single clock cycle, to achieves throughputs approaching 1 Million Instruction Per Second (MIPS) per MHz, enabling the system designed to optimise the power consumption. It includes a number of facilities for communicating with a computer or other microcontrollers through UART TTL(5 V) serial communication.
Optimization of Bio-Impedance Techniques-Based Monitoring System for Medical & Industrial Applications
Published in IETE Journal of Research, 2022
Ramesh Kumar, Sharwan Kumar, A. Sengupta
Generally, the controller unit has been used for current switching and measuring voltage values from the phantom. It also controls the switching panel for EIT methods and communicating with an AVR Programmer and computer via USB to TTL serial communicating device. The ATMEGA16 controller has been used in the proposed EIT system. ATMEGA16 [13] has 4 ports (Port A, Port B, Port C, Port D). Port C has been used for current switching through the analog multiplexers and Port B for measuring the data from the object by another two multiplexers. Port D is used for switching panel for EIT data acquisition methods and also this port is used to communicate with PC. Port A is used for data acquisition from the object and transfers all values from hardware to the computer through the controller pins PA0 and PA1, using USB to TTL device [21]. Figure 3(b) shows the schematic diagram of the controller ATMEGA16.