Memory device protected against undesirable supply voltage level
AssigneesHitachi, Ltd., Hitachi Ome Electronic Co., Ltd.
InventorsKouji Masuda, Masao Mizukami, Nobuaki Kitamura
Life of this patent
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Abstract
A memory circuit includes memory cells and access circuit for accessing to desired memory cells. The access circuit is driven by a driver which includes an emitter coupled logic for providing a switch-on signal of a low level in response to an input signal. A switch circuit in the driver provides the access circuit with a drive signal of a low level in response to the switch on signal. The driver further includes a control circuit for clamping the output of the emitter coupled logic to a non-drive signal of a high level when supply voltages does not satisfy predetermined conditions.
Claims9
A memory device comprising:
- memory circuit means including memory cells and means for accessing to desired memory cells;
- and
- driver means connected to said memory circuit means for driving said access means;
- wherein:
- said driver means comprises:
- emitter coupled logic means connected to first and second supply voltage for providing switch-on and switch-off signals in response to first and second input signals, respectively, wherein said first supply voltage is larger than said second supply voltage, said switch-on and switch-off signals lie between said second supply voltage and third supply voltage which lies between said first and second voltages, and said first and second input signals lie between said second and third supply voltages;
- switch means connected to said emitter coupled logic means for providing said access means with a drive signal of a low level in response to said switch-on signal and with a non-drive signal of a high level in response to said switch-off signal;
- and
- control means connected to said first to third supply voltages for clamping the output of said emitter coupled logic means to said non-drive signal when an operating point defined by said first and second supply voltages does not belong to a predetermined region, and wherein:
- said access means is means enabled in response to said drive signal.
Dependencies are inferred from the claim text.