MEMORY CIRCUIT WITH PROTECTION CIRCUIT

摘要

A memory circuit for use in a video signal processing circuit and, more particularly, an MOS-IC memory circuit capable of frame-by-frame storage of a video signal is disclosed. The memory circuit is provided with a protection circuit preventing the memory from being broken by an undesirable sequence of the main and substrate voltages or by an abnormal substrate voltage. The memory circuit includes first and second voltage input terminals to which first and second voltage are applied. A comparator generates a control signal when the voltage at the second input terminal is below a given level. The memory circuit operates in response to the first and second voltages and a switching circuit cuts off the first voltage when the control signal is generated. Where an MOS-IC chip is used there are a plurality of memory elements and the first and second voltages correspond to main and substrate voltages, respectively. If all the substrate voltage input terminals are wired by a single conductor passing sequentially through the terminals a single protection circuit can be used for all the memory elements.