\n \n<\/p>\n
\n"Transistor Transistor Logic"\n<\/p>\n
\nBasic voltage levels\n<\/p>\n
\nVOHmin (minimum HIGH output voltage) 2.4V
\nVOLmax (maximum LOW output voltage) 0.4V
\nVIHmin (minimum HIGH input voltage guaranteed to be recognised as logic 1) 2V
\nVILmax (maximum LOW input voltage guaranteed to be recognised as logic 0) 0.8V\n<\/p>\n
\nPower\n<\/p>\n
\nDraw a lot of power (individual gates may draw 3 to 4 mA).
\nLow power Schottky versions of TTL chips (LS) draw only 20% of the power, but are more expensive. \n<\/p>\n
\nInputs\n<\/p>\n
\nTTL low input sources current into whatever drives it (0.25mA for LS), so whatever is pulling it low must be able to sink current <<<THIS IS A CLASSIC ISSUE TO OVERLOOK!\n<\/p>\n
\nOutputs\n<\/p>\n
\nOutputs are saturated transistor to ground in LOW and a darlington follower in HIGH (2 diode drops below V+).
\nFor any TTL or CMOS family, any output should drive at least 10 inputs.\n<\/p>\n
\n"Complementary Metal Oxide Semiconductor Logic"\n<\/p>\n
\nThere are equivalents to most of the TTL chips, with CMOS devices having a 'C' in the middle of the part number: e.g. the 74C04 is the CMOS equivalent to the TTL 7404. \n<\/p>\n
\nBasic voltage levels\n<\/p>\n
\nVOHmin (minimum HIGH output voltage) 4.9V
\nVOLmax (maximum LOW output voltage) 0.1V
\nVIHmin (minimum HIGH input voltage guaranteed to be recognised as logic 1) 3.5V
\nVILmax (maximum LOW input voltage guaranteed to be recognised as logic 0) 1.5V\n<\/p>\n
\nPower\n<\/p>\n
\nMuch lower in power requirements (drawing about 1 mA).
\nOperate with a wide range of supply voltages (3 to 18 volts).\n<\/p>\n
\nInputs\n<\/p>\n
\nCMOS draws no input current.
\nCMOS input threshold usually 1\/3 to 2\/3 the supply voltage.\n<\/p>\n
\nOutputs\n<\/p>\n
\nOutputs are MOSFET and therefore rail to rail.
\nFor any TTL or CMOS family, any output should drive at least 10 inputs.\n<\/p>\n
\n74 (no letters, e.g. 7400)\n<\/p>\n
\nTTL\n<\/p>\n
\n74LS\n<\/p>\n
\nEarly TTL low power Schottky. Improved 7400\n<\/p>\n
\n74ALS\n<\/p>\n
\nHigher speed, lower power TTL than LS\n<\/p>\n
\n74AS\n<\/p>\n
\n74F00\n<\/p>\n
\nHigh speed Fast TTL improvement on LS\n<\/p>\n
\n4000B\n<\/p>\n
\nClassic CMOS family. Static sensitive 3v to 15v supplies. 0.4mA source sink drive current.\n<\/p>\n
\n74C\n<\/p>\n
\n3 to 15 VCC\n<\/p>\n
\n74HC\n<\/p>\n
\n2.0 to 6.0 VCC \n74HCT\n<\/p>\n \n4.5 to 5.5 VCC \n74AC\n<\/p>\n \n2.0 to 6.0 VCC \n \n<\/p>\n \n74ACT\n<\/p>\n \n4.5 to 5.5 VCC \n74ABT\n<\/p>\n \n64mA per output, low noise\n<\/p>\n \n74FCT\n<\/p>\n \nCMOS. Bus interface devices. Lower power than 74F due to CMOS technology. \n74LV\n<\/p>\n \nCMOS 3.3v supply\n<\/p>\n \n74LVC\n<\/p>\n \nCMOS 3.3v supply, faster improved output over LV\n<\/p>\n \n74VHC\n<\/p>\n \n <\/p>\n","protected":false},"excerpt":{"rendered":" TTL "Transistor Transistor Logic" Basic voltage levels VOHmin (minimum HIGH output voltage) 2.4V VOLmax (maximum LOW output voltage) 0.4V VIHmin (minimum HIGH input voltage guaranteed to be recognised as logic 1) 2V VILmax (maximum LOW input voltage guaranteed to be recognised as logic 0) 0.8V Power Draw a lot of power (individual gates may […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[91,90],"tags":[],"class_list":["post-1487","post","type-post","status-publish","format-standard","hentry","category-gates","category-logic-families"],"_links":{"self":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1487","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/comments?post=1487"}],"version-history":[{"count":6,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1487\/revisions"}],"predecessor-version":[{"id":1493,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1487\/revisions\/1493"}],"wp:attachment":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/media?parent=1487"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/categories?post=1487"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/tags?post=1487"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n4mA\/6mA Sink\/Source
\nBasic high speed CMOS similar to TTL.
\nTHE HC IS THE BASIC SIMPLE LOGIC GATE CHOICE FOR MANY APPLICATIONS<\/em>\n<\/p>\n
\n4mA\/6mA Sink\/Source\u200b
\nThe HCT and ACT CMOS families are designed with a low threshold similar to TTL for compatability (since bipolar TTL outputs do not swing all the way to +V). \n<\/p>\n
\n24mA Sink\/Source drive current.\n<\/p>\n
\nACT has TTL compatible inputs.\u200b
\nMin high level voltage = 2V so these can be used to interface 3V3 IC’s to 5V IC’s.
\nThe HCT and ACT CMOS families are designed with a low threshold similar to TTL for compatability (since bipolar TTL outputs do not swing all the way to +V). \n<\/p>\n
\n64mA, 48mA Sink Current Capability\n<\/p>\n