SCHA005B January 2015 – December 2022 74AC11074 , 74AC16373 , 74AC16374 , 74ACT11074 , 74ACT11373 , 74ACT11374 , 74ACT16373 , 74ACT16374 , 74ACT16823 , 74ACT16841 , CD4006B-MIL , CD4013B , CD4013B-MIL , CD4014B , CD4014B-MIL , CD4015B , CD4015B-MIL , CD40174B , CD40174B-MIL , CD40175B , CD40175B-MIL , CD40194B , CD4021B , CD4021B-MIL , CD4021B-Q1 , CD4027B , CD4027B-MIL , CD4031B , CD4031B-MIL , CD4034B , CD4034B-MIL , CD4035B , CD4035B-MIL , CD4042B , CD4042B-MIL , CD4043B , CD4043B-MIL , CD4044B , CD4044B-MIL , CD4076B , CD4076B-MIL , CD4094B , CD4094B-MIL , CD4099B , CD4099B-MIL , CD4508B , CD4508B-MIL , CD4517B , CD4517B-MIL , CD4724B , CD4724B-MIL , CD54AC109 , CD54AC112 , CD54AC164 , CD54AC273 , CD54AC299 , CD54AC373 , CD54AC374 , CD54AC573 , CD54AC574 , CD54AC74 , CD54ACT109 , CD54ACT112 , CD54ACT164 , CD54ACT174 , CD54ACT273 , CD54ACT299 , CD54ACT373 , CD54ACT374 , CD54ACT573 , CD54ACT574 , CD54ACT74 , CD54HC107 , CD54HC109 , CD54HC112 , CD54HC164 , CD54HC165 , CD54HC166 , CD54HC173 , CD54HC174 , CD54HC175 , CD54HC194 , CD54HC259 , CD54HC273 , CD54HC299 , CD54HC373 , CD54HC374 , CD54HC377 , CD54HC4015 , CD54HC4094 , CD54HC533 , CD54HC534 , CD54HC563 , CD54HC564 , CD54HC573 , CD54HC574 , CD54HC597 , CD54HC73 , CD54HC74 , CD54HC75 , CD54HCT109 , CD54HCT112 , CD54HCT164 , CD54HCT165 , CD54HCT166 , CD54HCT173 , CD54HCT174 , CD54HCT175 , CD54HCT259 , CD54HCT273 , CD54HCT299 , CD54HCT373 , CD54HCT374 , CD54HCT377 , CD54HCT533 , CD54HCT534 , CD54HCT564 , CD54HCT573 , CD54HCT574 , CD54HCT74 , CD54HCT75 , CD74AC109 , CD74AC112 , CD74AC164 , CD74AC174 , CD74AC175 , CD74AC273 , CD74AC299 , CD74AC323 , CD74AC373 , CD74AC374 , CD74AC534 , CD74AC573 , CD74AC574 , CD74AC74 , CD74ACT109 , CD74ACT112 , CD74ACT164 , CD74ACT174 , CD74ACT175 , CD74ACT273 , CD74ACT299 , CD74ACT373 , CD74ACT374 , CD74ACT573 , CD74ACT574 , CD74ACT74 , CD74ACT74-Q1 , CD74FCT273 , CD74FCT374 , CD74FCT843A , CD74HC107 , CD74HC109 , CD74HC112 , CD74HC164 , CD74HC165 , CD74HC166 , CD74HC173 , CD74HC174 , CD74HC175 , CD74HC194 , CD74HC195 , CD74HC259 , CD74HC273 , CD74HC299 , CD74HC373 , CD74HC374 , CD74HC377 , CD74HC4015 , CD74HC4094 , CD74HC533 , CD74HC534 , CD74HC563 , CD74HC564 , CD74HC573 , CD74HC574 , CD74HC595 , CD74HC597 , CD74HC670 , CD74HC73 , CD74HC74 , CD74HC75 , CD74HCT107 , CD74HCT109 , CD74HCT112 , CD74HCT164 , CD74HCT165 , CD74HCT166 , CD74HCT173 , CD74HCT174 , CD74HCT175 , CD74HCT194 , CD74HCT259 , CD74HCT273 , CD74HCT299 , CD74HCT373 , CD74HCT374 , CD74HCT377 , CD74HCT4094 , CD74HCT533 , CD74HCT534 , CD74HCT563 , CD74HCT564 , CD74HCT573 , CD74HCT574 , CD74HCT574-EP , CD74HCT574-Q1 , CD74HCT597 , CD74HCT670 , CD74HCT73 , CD74HCT74 , CD74HCT75 , CY54FCT273T , CY54FCT373T , CY54FCT374T , CY54FCT377T , CY54FCT573T , CY54FCT574T , CY54FCT841T , CY74FCT162374T , CY74FCT16374T , CY74FCT2373T , CY74FCT2573T , CY74FCT2574T , CY74FCT273T , CY74FCT373T , CY74FCT374T , CY74FCT573T , CY74FCT574T , SN54107 , SN54166 , SN54173 , SN5472 , SN5476 , SN54ABT16373A , SN54ABT16374A , SN54ABT273 , SN54ABT373 , SN54ABT374 , SN54ABT377 , SN54ABT533 , SN54ABT534 , SN54ABT573 , SN54ABT574 , SN54ABT821 , SN54ABT823 , SN54ABT841 , SN54ABT843 , SN54AC373 , SN54AC373-SP , SN54AC374 , SN54AC574 , SN54AC74 , SN54AC74-SP , SN54ACT16373 , SN54ACT373 , SN54ACT373-SP , SN54ACT374 , SN54ACT374-SP , SN54ACT573 , SN54ACT74 , SN54AHC273 , SN54AHC373 , SN54AHC374 , SN54AHC573 , SN54AHC574 , SN54AHC74 , SN54AHCT373 , SN54AHCT374 , SN54AHCT573 , SN54AHCT574 , SN54AHCT74 , SN54ALS109A , SN54ALS112A , SN54ALS174 , SN54ALS175 , SN54ALS259 , SN54ALS273 , SN54ALS29821 , SN54ALS299 , SN54ALS323 , SN54ALS373A , SN54ALS374A , SN54ALS563B , SN54ALS564B , SN54ALS573C , SN54ALS574B , SN54ALS576B , SN54ALS580B , SN54ALS74A , SN54ALS873B , SN54ALS874B , SN54ALS996 , SN54AS174 , SN54AS175B , SN54AS374 , SN54AS573A , SN54AS574 , SN54AS74A , SN54AS821A , SN54AS823A , SN54AS825A , SN54BCT373 , SN54BCT374 , SN54BCT574 , SN54BCT8374A , SN54F109 , SN54F373 , SN54F374 , SN54F74 , SN54HC109 , SN54HC109-SP , SN54HC112 , SN54HC164 , SN54HC164-SP , SN54HC165 , SN54HC166 , SN54HC166-SP , SN54HC174 , SN54HC175 , SN54HC195 , SN54HC259 , SN54HC273 , SN54HC273-DIE , SN54HC273-SP , SN54HC373 , SN54HC373-DIE , SN54HC373-SP , SN54HC374 , SN54HC374-SP , SN54HC377 , SN54HC573A , SN54HC573A-SP , SN54HC574 , SN54HC595 , SN54HC595-SP , SN54HC74 , SN54HC74-SP , SN54HCT373 , SN54HCT373-SP , SN54HCT374 , SN54HCT74 , SN54LS109A , SN54LS112A , SN54LS164 , SN54LS164-SP , SN54LS165A , SN54LS165A-SP , SN54LS166A , SN54LS173A , SN54LS174 , SN54LS175 , SN54LS194A , SN54LS195A , SN54LS273 , SN54LS273-SP , SN54LS279A , SN54LS299 , SN54LS323 , SN54LS373 , SN54LS373-SP , SN54LS374 , SN54LS375 , SN54LS377 , SN54LS378 , SN54LS379 , SN54LS595 , SN54LS597 , SN54LS670 , SN54LS673 , SN54LS674 , SN54LS73A , SN54LS74A , SN54LS74A-SP , SN54LS75 , SN54LS76A , SN54LS91 , SN54LVC373A , SN54LVC374A , SN54LVC573A , SN54LVC574A , SN54LVC74A , SN54LVC74A-SP , SN54LVTH162373-SP , SN54LVTH162374-SP , SN54LVTH16373 , SN54LVTH373 , SN54LVTH374 , SN54LVTH573 , SN54LVTH574 , SN54LVTH574-SP , SN54S112 , SN54S174 , SN54S175 , SN54S194 , SN54S373 , SN54S374 , SN54S74 , SN74ABT162823A , SN74ABT162841 , SN74ABT16373A , SN74ABT16373A-EP , SN74ABT16374A , SN74ABT16821 , SN74ABT16823 , SN74ABT16841 , SN74ABT16843 , SN74ABT273 , SN74ABT373 , SN74ABT374A , SN74ABT377A , SN74ABT533A , SN74ABT534A , SN74ABT573A , SN74ABT574A , SN74ABT821A , SN74ABT823 , SN74ABT841A , SN74ABT843 , SN74ABTH162260 , SN74ABTH16260 , SN74ABTH16823 , SN74AC373 , SN74AC373-EP , SN74AC374 , SN74AC533 , SN74AC534 , SN74AC563 , SN74AC564 , SN74AC573 , SN74AC574 , SN74AC74 , SN74AC74-EP , SN74ACT16373-EP , SN74ACT16374-EP , SN74ACT373 , SN74ACT373-EP , SN74ACT374 , SN74ACT533 , SN74ACT534 , SN74ACT563 , SN74ACT564 , SN74ACT573 , SN74ACT574 , SN74ACT74 , SN74ACT74-EP , SN74AHC16373 , SN74AHC16374 , SN74AHC174 , SN74AHC273 , SN74AHC373 , SN74AHC374 , SN74AHC573 , SN74AHC574 , SN74AHC594 , SN74AHC595 , SN74AHC595-Q1 , SN74AHC74 , SN74AHC74-EP , SN74AHC74Q-Q1 , SN74AHCT16373 , SN74AHCT16374 , SN74AHCT174 , SN74AHCT273 , SN74AHCT373 , SN74AHCT374 , SN74AHCT573 , SN74AHCT574 , SN74AHCT594 , SN74AHCT595 , SN74AHCT74 , SN74AHCT74-EP , SN74AHCT74Q-Q1 , SN74ALS109A , SN74ALS112A , SN74ALS164A , SN74ALS165 , SN74ALS166 , SN74ALS174 , SN74ALS175 , SN74ALS259 , SN74ALS273 , SN74ALS29821 , SN74ALS299 , SN74ALS323 , SN74ALS373A , SN74ALS374A , SN74ALS533A , SN74ALS534A , SN74ALS563B , SN74ALS564B , SN74ALS573C , SN74ALS574B , SN74ALS575A , SN74ALS576B , SN74ALS577A , SN74ALS580B , SN74ALS666 , SN74ALS667 , SN74ALS74A , SN74ALS841 , SN74ALS843 , SN74ALS873B , SN74ALS874B , SN74ALS990 , SN74ALS992 , SN74ALS996 , SN74ALVCH162260 , SN74ALVCH162373 , SN74ALVCH162374 , SN74ALVCH16260 , SN74ALVCH162721 , SN74ALVCH162841 , SN74ALVCH16373 , SN74ALVCH16374 , SN74ALVCH16721 , SN74ALVCH16820 , SN74ALVCH16821 , SN74ALVCH16823 , SN74ALVCH16841 , SN74ALVCH373 , SN74ALVCH374 , SN74ALVTH16373 , SN74ALVTH16374 , SN74ALVTH16821 , SN74AS109A , SN74AS174 , SN74AS175B , SN74AS194 , SN74AS373 , SN74AS374 , SN74AS573A , SN74AS574 , SN74AS576 , SN74AS74A , SN74AS874 , SN74AUC16373 , SN74AUC16374 , SN74AUC1G74 , SN74AUC1G79 , SN74AUC1G80 , SN74AUC2G79 , SN74AUC2G80 , SN74AUC74 , SN74AUCH16374 , SN74AUP1G74 , SN74AUP1G79 , SN74AUP1G80 , SN74AUP2G79 , SN74AUP2G80 , SN74AVC16373 , SN74AVC16374 , SN74AVC16722 , SN74BCT374 , SN74BCT573 , SN74BCT574 , SN74F109 , SN74F112 , SN74F174A , SN74F175 , SN74F299 , SN74F373 , SN74F374 , SN74F377A , SN74F573 , SN74F574 , SN74F74 , SN74HC109 , SN74HC112 , SN74HC164 , SN74HC165 , SN74HC165-EP , SN74HC165-Q1 , SN74HC166 , SN74HC166A-EP , SN74HC166A-Q1 , SN74HC174 , SN74HC175 , SN74HC259 , SN74HC273 , SN74HC273-Q1 , SN74HC373 , SN74HC374 , SN74HC377 , SN74HC563 , SN74HC573A , SN74HC573A-Q1 , SN74HC574 , SN74HC594 , SN74HC595 , SN74HC595-EP , SN74HC74 , SN74HC74-EP , SN74HC74-Q1 , SN74HCT273 , SN74HCT373 , SN74HCT374 , SN74HCT377 , SN74HCT573 , SN74HCT574 , SN74HCT74 , SN74LS107A , SN74LS109A , SN74LS112A , SN74LS164 , SN74LS165A , SN74LS166A , SN74LS173A , SN74LS174 , SN74LS175 , SN74LS194A , SN74LS259B , SN74LS273 , SN74LS279A , SN74LS299 , SN74LS373 , SN74LS374 , SN74LS375 , SN74LS377 , SN74LS378 , SN74LS594 , SN74LS595 , SN74LS597 , SN74LS598 , SN74LS670 , SN74LS673 , SN74LS674 , SN74LS73A , SN74LS74A , SN74LS75 , SN74LV164A , SN74LV165A , SN74LV165A-EP , SN74LV165A-Q1 , SN74LV166A , SN74LV174A , SN74LV175A , SN74LV273A , SN74LV373A , SN74LV373A-Q1 , SN74LV373AT , SN74LV374A , SN74LV374A-EP , SN74LV374A-Q1 , SN74LV374AT , SN74LV573A , SN74LV573AT , SN74LV574A , SN74LV594A , SN74LV595A , SN74LV595A-EP , SN74LV595A-Q1 , SN74LV74A , SN74LV74A-EP , SN74LV74A-Q1 , SN74LV8153 , SN74LV8153-Q1 , SN74LVC112A , SN74LVC16373 , SN74LVC16373A , SN74LVC16373A-EP , SN74LVC16374 , SN74LVC16374A , SN74LVC1G175 , SN74LVC1G175-EP , SN74LVC1G373 , SN74LVC1G374 , SN74LVC1G374-Q1 , SN74LVC1G74 , SN74LVC1G79 , SN74LVC1G79-EP , SN74LVC1G80 , SN74LVC2G74 , SN74LVC2G74-EP , SN74LVC2G74-Q1 , SN74LVC2G79 , SN74LVC2G80 , SN74LVC373A , SN74LVC373A-EP , SN74LVC374A , SN74LVC374A-EP , SN74LVC374A-Q1 , SN74LVC573A , SN74LVC573A-EP , SN74LVC573A-Q1 , SN74LVC574A , SN74LVC574A-EP , SN74LVC574A-Q1 , SN74LVC74A , SN74LVC74A-EP , SN74LVC74A-Q1 , SN74LVC821A , SN74LVC823A , SN74LVC841A , SN74LVCH16373A , SN74LVCH16374A , SN74LVCH32373A , SN74LVTH162373 , SN74LVTH162373-EP , SN74LVTH162374 , SN74LVTH16373 , SN74LVTH16373-EP , SN74LVTH16374 , SN74LVTH16374-EP , SN74LVTH273 , SN74LVTH273-EP , SN74LVTH373 , SN74LVTH373-EP , SN74LVTH374 , SN74LVTH374-EP , SN74LVTH573 , SN74LVTH573-EP , SN74LVTH574 , SN74LVTH574-EP , SN74S112A , SN74S175 , SN74S374 , SN74S74
PRODMIX
Some logic devices, such as flip-flops and shift registers, require the use of a clock input, typically designated CLK or CP. The state of the outputs of these devices change once an appropriate clock edge has occurred. Device datasheets specify whether the action occurs on a positive or negative edge of the clock. However, the behavior of a device upon power-up is not always specified before a valid clock edge has occurred.
The CD74HC4094 is an example of a device that does not have guaranteed output levels upon power-up. Before a valid clock edge, thresholds within the device can cause the internal logic chains to product high or low signals. This effect can vary with voltage, temperature, manufacturing lot, and more. As a result, the outputs Qn will be determined by unpredictable power-up states determined by these internal thresholds and should not be considered valid logic signals. However, once a valid clock edge has occurred, the outputs behave normally according to the truth table in the datasheet. For this particular device, 8 clock edges are required to shift the unknown data out of the device and ensure that all Qn outputs are valid.
Another important consideration is the rise of the CLK signal simultaneously with VCC. Although the clock signal will be seen as an appropriate edge on an oscilloscope, the device may not consider it a valid clock. As VCC rises, the VIH threshold of the clock signal also rises. If the two rise simultaneously, the clock signal may or may not cross the appropriate thresholds required to be considered valid. Capacitance within the circuit will also cause subtle and unpredictable differences in the timing of CLK and VCC. Therefore, it is not recommended to produce a clock edge until VCC has risen to a recommended level as specified in the device datasheet.
There are several methods that designers can use to prevent unwanted signals at power-up from affecting their systems.