ApplicationNo. 06/664344 filed on 10/24/1984
US Classes:326/14, Fail-safe326/104, FUNCTION OF AND, OR, NAND, NOR, OR NOT326/124Bipolar transistor (e.g., RTL, DCTL, etc.)
ExaminersPrimary: Miller, Stanley D.
Assistant: Hudspeth, D. R.
Attorney, Agent or Firm
International ClassH03K 19/007 (20060101)
Foreign Application Priority Data1983-10-26 FR
AbstractThe invention involves an "AND" logic circuit with built-in safety comprising a first and a second input to which pulses can be applied, and respectively tied to the base of a first and a second transistor (1,2) each having a collector to which a reference voltage (5) is applied by means of a corresponding resistance (6,7), and comprising, in addition, a third transistor (3) having its base tied to ground by means of the secondary winding (15) of a transformer whose transforming ratio is less than unity, its collector tied to the positive terminal of the d.c. voltage supply by means of a resistance (13), and its emitter having the reference voltage (5) applied thereto. According to the invention, the first transistor (1) has its emitter tied by means of a first diode (8) and its collector tied by means of a capacitor (9) to ground, whereas the second transistor (2) has its emitter directly tied and its collector tied by means of a branch comprising a capacitor (10) and a second diode (11) in series to ground. The anode of the first diode (8) and the cathode of the second diode (11) are tied to ground.