Introductory Medical Device Prototyping Digital Circuits Part 1 Logic Gates, http://saliterman.umn.edu/ Department of Biomedical Engineering, University of Minnesota
Topics Digital Electronics CMOS Logic National Instrument s Multisim (SPICE) and Ultiboard Software Prototyping with Breadboards Boolean Logic CMOS and TTL IC Packaging and Pinouts Various Devices and Circuits Schmitt triggers Contact debouncing Simulation and elimination of noise; voltage summing Leading edge detection Counters and 7-segment display Drivers for LEDs, lamps and relays Field Programmable Gate Arrays (FPGA)
Microelectronics Revolution Triode tube 1915 (Langmuir) Point-contact transistor 1947, Bell Labs (Brattain and Bardeen). Junction transistor 1948 (Shockley), IC 1958 (Kibly and Noyce), & Intel Pentium Microprocessor 10 8 Transistors!
From Molten Silicon to IC Chips Molten silicon - Czochralski puller technique Silicon wafer diced into integrated circuits (DIP and SMD). Single crystal silicon boule
CMOS Logic Complementary Metal Oxide Semiconductor Logic (4000B and 74HC00 series) Wide range of power supply voltages, from 3 to 15 Vdc Logic changes half-way up the power supply voltage, giving good noise immunity. Almost no power supply current needed except during input logic changes. Inputs are open circuits and easy to drive. The unloaded output logic swings the full range of the power supply. CMOS circuits create little noise of their own. CMOS circuits pass along less noise. Low cost.
Design with NI Multisim
CMOS Packages & Pins Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
Inverter 74HC04 Notice the output is inverse to the input. Input High Low Output Low High
Available Logic Gates in the 74HC04 Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
NAND 74HC00 Input 1 Input 2 Output 0 0 1 1 0 1 0 1 1 1 1 0 If either or both inputs are low the output will be high.
Available Logic Gates in the 74HC00 In addition to this NAND gate, there are many different types and combinations of Boolean logic gates to select from. These include AND, OR, NOR, Exclusive OR & NOR and others. Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
Flip-Flop 74HC74 QQ QQ Notice the divide by 2 of frequency. The information presented to the D input goes on to the QQ output whenever the clock input changes from a low to a high level. If D is high, on clocking, QQ goes high and QQ goes low. If D is low, on clocking, QQ goes low and QQ goes high.
4 Bit Binary Counter with Buffer Drivers Place 2 3 =8 2 2 =4 2 1 =2 2 0 =1
Available Logic Gates in the 74HC74 In addition to this D-Flip-Flop, there are also JK Flip-Flops Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
Counter on Breadboard
Tri-State Logic 74HC126
Available Logic Gates in the 74HC126 Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
Schmitt Trigger 74C14
Switch Contact Noise Thresholds are ~ 1.35 V for Low and 3.15 V for High Mechanical contact noise can cause multiple pulses to occur the first 100 µs or so. In this example, three pulses would be generated.
Contact Debouncer Schmitt Trigger Output Input Switch Off & On
Creating Noise with Voltage Summing Voltage Summing Voltage Inverter
Noise Eliminator Schmitt Trigger 4093B Summer Input Output Voltage Follower
Leading Edge Detector Schmitt Trigger Debounced button pushes Single pulse with each positive edge
Available Logic Gates in the 74HC14 & 4093B Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
One-and-only One Synchronized Pulse Clock Button Output is a synchronized pulse with the clock, while the button push is not.
Driving LEDs 4049B Current sourcing. Current sinking. RR 1 oooo 2 = VV FF II FF The 4049 Inverter- Buffer can source or sink sufficient current to light the LED directly. For other CMOS logic you need to have a transistor. Push Button Debounce Certain devices, like counters, may have built in LED drivers.
Available Logic Gates in the 4049B Lancaster, D. and Berlin, H.M. CMOS Cookbook. H.W. Sams, Indianapolis, IN (1988)
Lamp Driver with Transistor Lamp is rated 5 V and power of 200 mw. Required current: PPPPPPPPPP WW = II 2 RR = VVVV II = PPPPPPPPPP WW 200 mmmm = = 40 mmmm VV The 2N2222 is a general purpose medium power amplifier and switch, for I C of up to 500 ma (max. 1 A). 5
MOSFET Relay Driver with Transient Suppression MOSFET is a transconductance device (base current is negligible, base voltage controls collector current). The MOSFET allows for higher collector current than the BJT.
Field Programmable Gate Arrays (FPGA) These are ICs that can be programmed in the field with Hardware Descriptive Language (HDL). They contain an array of programmable logic blocks that can be wired together with software. Images from Wikipedia, used under Creative Commons
Summary CMOS Logic Designing with NI Multisim (SPICE) and Ultiboard Software Prototyping with Breadboards Boolean Logic CMOS Packaging and Pinouts Various Devices and Circuits Schmitt triggers Contact debouncing Simulation and elimination of noise; voltage summing Leading edge detection Counters and 7-segment display Drivers for LEDs, lamps and relays Field Programmable Gate Arrays