Battery backup circuit of memory

Abstract

Abstract PURPOSE:To prevent an erroneous data from being written in a memory by delaying a reset signal, and using it as a timing for turning off a memory access signal in case when a power source is cut off. CONSTITUTION:A microprocessor 10 and an RAM11 are connected to power source lines La, Lb, and both of them execute read-out and write of a data through an address latching circuit 12, a gate circuit 13 and a bus line B. A voltage drop detecting circuit 20 is connected between said power source lines, and a detected voltage drop is held by a reset holding circuit 21, and sent to a D- type flip-flop 22 and a delaying circuit 23. In this way, a reset signal is generated by a detecting signal of a voltage drop, a transistor Q is turned off (a main power source is cut off, and a current is fed from a battery E) by making it synchronize with an ALE signal of the mircroprocessor 10, also a chip selecting signal is stop, the reset signal is delayed, and the microprocessor 10 is reset.

Inventors

• 👤 Hiroshi Hashimoto
• 👤 橋本　央

Bibliographic Details