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Edge Triggered Reset/Set DC Trigger

IP.com Disclosure Number: IPCOM000079598D
Original Publication Date: 1973-Aug-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Hornung, LM: AUTHOR

Abstract

The DC triggers shown in Figs. 1 and 2 are represented in Monolithic System Technology, which is similar to the industry standard MECL. The basic logical circuit provides both a NOR function and an OR function. The logic blocks are represented as rectangular forms in the figures with inputs on the left and outputs on the right. The NOR and OR outputs are the upper and lower outputs, respectively. Emitter-followers are represented by a diamond. Dot functions which input to emitter-followers constitute logical AND functions. AND dot functions of emitter-follower outputs form logical OR functions.

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Edge Triggered Reset/Set DC Trigger

The DC triggers shown in Figs. 1 and 2 are represented in Monolithic System Technology, which is similar to the industry standard MECL. The basic logical circuit provides both a NOR function and an OR function. The logic blocks are represented as rectangular forms in the figures with inputs on the left and outputs on the right. The NOR and OR outputs are the upper and lower outputs, respectively. Emitter-followers are represented by a diamond. Dot functions which input to emitter-followers constitute logical AND functions. AND dot functions of emitter-follower outputs form logical OR functions.

The standard DC trigger, which is shown in Fig. 1, is commonly used in control circuits. The trigger has complementary outputs A(out) and B(out). When used in "clocked sequential" control circuits, the Set C input is connected to a common clock which is regular with respect to its period. The state, which the trigger is to assume, is controlled through inputs A(in) and B(in). The trigger consists of three cross-coupled bistable devices. The final stage furnishes the outputs of the trigger, A(out) and B(out). Outputs from the other two bistable devices are identified as X and Y. X and Y have special significance with respect to A(in) and B(in), respectively. If A(in) is true, B(in) is false, and Set C undergoes a down-going transition, X will set; X will, in turn, cause B(out) to be false and A(out) to be true. In a similar manner, if B(in) is true, A(in) is false, and Set C has a down-going transition, Y will set which will in turn, cause A(out) to be false and B(out) to be true. Whenever X or Y is set, the trigger is closed to its inputs. In actual practice, A(in) and B(in) are logical complements so that X or Y sets immediately after Set Z goes negative, and A(in) and B(in) may change values soon after the negative going transition of Set C, without having effect on the operation of the trigger.

If neither A(in) or B(in) is true when Set C has a negative transition, neither X or Y sets and the trigger remains open to the inputs A(in) and B(in). If subsequently...