- #TOTEM POLE OUTPUT FOR TTL LOGIC FAMILIES DRIVERS#
- #TOTEM POLE OUTPUT FOR TTL LOGIC FAMILIES DRIVER#
- #TOTEM POLE OUTPUT FOR TTL LOGIC FAMILIES SERIES#
Opn collector devices do a much better job of this. Totem pole is not easily paralled with other similar devices to create 'wired OR" arrangements. Switches between on chip supply rails (say Vdd and Ground) so does not allow loads to be switched at voltages above supply rail.Ī non totem pole design of one of the 3 main sorts has various pros and cons. Is "always on" either pulling up or pulling down or a bit of both.
Whether this is an issue depends greatly on application and design.
#TOTEM POLE OUTPUT FOR TTL LOGIC FAMILIES DRIVERS#
Has to be designed to avoid excessive (or any) "shoot through" current when both drivers are on at once. Provides active and so controlled and potentially high level and fast drive in both directions. This is like using a passive resistive pullup but has somewhat different characteristics. This allows users to add their own "pullup" which is the the "load fopr the active driver, and/or to connect a number of such stages in parallel with a single load shared by all.Ĭurrent source pullup. The alternatives to a totem pole stage are -Ī passive pullup (or pulldown) where a resistor is used to provide drive in one direction and is "pulled" in the other directionby an active device.Īn "open collector" drive where there is an active device "pulling" in one direction and nothing pulling in the other. Q2 & Q3 form a complementary push-pull output pair - less commonly implied by totm pole terminology. See diagram below - two for the price of one. This is usually what is implied by the term. See diagram below - classic totem-pole output with drivers of same polarity at top and bottom. As there is no Valve equivalent to a PNP transistor, complementary pair designs were not possible.
#TOTEM POLE OUTPUT FOR TTL LOGIC FAMILIES SERIES#
The term originally was used in pre transistor thermionic valve designs where two stages were placed in series in the same manner. This arrangement has become so common that it is often what is envisaged when the term "totem pole" is used, even though a complementary pair can serve the same purposes.
#TOTEM POLE OUTPUT FOR TTL LOGIC FAMILIES DRIVER#
Nothing new added.Ī totem pole driver or output stage is a loose term used to mean that the output is driven actively in both the high and low directions.Ī totem pole output can be an NPN/PNP or N Channel/P Channel "complementary pair" or, as is the case in many TTL logic devices, two devices of the same polarity stacked on top of each other. *- Points in this summary are already covered below. I guess it has to do with the low-voltage process, but it does take away the open drain's most interesting feature.Ī totem pole driver or output is fast and relatively "powerful" when switching in either direction compared to passive resistor stages or current source or open collector loaded stages.Ī totem pole arrangement is not suitable for paralleling with other divers to make "wired OR" stages - which can be useful in some applications.Ī totem pole driver switches "between its supply rails" so cannot drive loads which are connected on one end to voltages outside the supply rails - as is required in some applications.
So don't use them when you need to both source and sink current.