totem-pole si open collector

#1
mirku

Posted 26 January 2005 - 23:39

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Dc stie cineva care este diferenta intre cele doua tipuri de iesire pt familia TTL ..totem-pole si open collector rog a-mi explica si mie!!
Multumesc!!

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#2
Acta non verba

Posted 27 January 2005 - 00:54

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Quote

What is an Open Collector Output?
An Open Collector output is a NPN transistor. A NPN transistor allows the sinking of current to common. It can be thought of as a switch that allows the circuit, after the load, to be connected to common. This means that a source is required for the output to work. A supply through a load must be connected to the output, otherwise the NPN transistor is simply creating a path to common, i.e. a dry contact. Therefore, if you were to measure the voltage at the output of an open collector that is not hooked up to some supply you would not see a change in voltage. The voltage should be measured across the output load to determine if the open collector is working properly.

deci: OPEN colector= se refera la modul de realizarea a iesirii unui circuit logic... in situatia de OC circuitul are la iesire un tranzistor (NPN) al carui colector este liber si pentru a functiona este nevoie de o sarcina. Acest tip de iesire poate doar sa consume curent si de obicei se bazeaza pe faptul ca sarcina conectata in colector furnizeaza tensiunea necesara logicii de "1" iar tranzistorul poate doar sa forteze trecerea in starea logica "0"...

Quote

What is a Totem Pole Output?

A Totem Pole output is essentially the same as a Push Pull output; however, it is the terminology commonly used when referring to a TTL device. The major difference between it and a Push Pull is the amount of current that it can sink or source. The Totem Pole output is going to sink/source less current then a Push Pull output is capable of sinking or sourcing. The other major difference is the output voltage between the two. The Totem Pole is a 5V DC signal only, where the Push Pull will follow the input voltage.

Aici etajul de iesire are posibilitatea de a furniza atit nivelul logic "0" cit si nivel logic "1" chiar in absenta sarcinii/circuitelor exterioare... Se aseamana cu montajul Push Pull de la amplificatoarele liniare cu deosebirea ca exista o diferenta intre curentul furnizat si cel pe care-l poate consuma din exterior iar tensiunea la iesire nu variaza proportional cu valoarea tensiunii aplicate la intrare ca la Push Pull ci trece brusc in valoare logica "1", adica uzual +5V...

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Edited by Acta non verba, 27 January 2005 - 01:06.

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#3
mirku

Posted 27 January 2005 - 00:59

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Mersi!!!!

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totem-pole si open collector

#1 mirku Posted 26 January 2005 - 23:39

#2 Acta non verba Posted 27 January 2005 - 00:54

#3 mirku Posted 27 January 2005 - 00:59

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#1
mirku

Posted 26 January 2005 - 23:39

#2
Acta non verba

Posted 27 January 2005 - 00:54

#3
mirku

Posted 27 January 2005 - 00:59