VARIATION DETECTING CIRCUIT

摘要

PURPOSE:To eliminate the need to use numbers of inverters and Ex-ORs by cascading the 1st and the 2nd transistors (TR) and interposing a resistance at a low potential side. CONSTITUTION:The 1st and the 2nd TRs 2 and 3 are cascaded and the resistance is connected to the emitter of the 2nd TR3. A driving circuit is provided between an input terminalIand the bases of the 1st and the 2nd TRs. Further, a variation holding circuit 5 which is set when the voltage drop across the resistance 4 reaches a prescribed level is provided across the resistance 4. The circuit 5 detects the voltage drop across the resistance 4 when the TRs 2 and 3 are both activated.