MEMORY TEST MODE FOR CHARGE RETENTION TESTING
First Claim
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1. A method, comprising:
- disabling an autonomous refresh mode of a dynamic random access memory circuit on a die which is adapted to autonomously refresh the memory cells of the memory circuit at a first autonomous refresh mode rate;
enabling a test refresh mode;
refreshing said memory cells during said test refresh mode at a second test refresh mode rate which is higher than said first autonomous refresh mode rate and is a function of the output of a timer circuit external to the die of the memory circuit; and
testing said memory circuit wherein the results of said testing is a function of the charge retention of said memory cells.
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Abstract
One embodiment includes a dynamic memory operable in different refresh modes including an autonomous refresh mode in which the refresh rate is set by an internal self refresh timer circuit on the memory circuit die, and a test refresh mode in which the refresh rate is set by a timer circuit external to the memory circuit die. Other embodiments are described and claimed.
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Citations
14 Claims
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1. A method, comprising:
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disabling an autonomous refresh mode of a dynamic random access memory circuit on a die which is adapted to autonomously refresh the memory cells of the memory circuit at a first autonomous refresh mode rate; enabling a test refresh mode; refreshing said memory cells during said test refresh mode at a second test refresh mode rate which is higher than said first autonomous refresh mode rate and is a function of the output of a timer circuit external to the die of the memory circuit; and testing said memory circuit wherein the results of said testing is a function of the charge retention of said memory cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for use with an external timer circuit, comprising:
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a first die; and an integrated circuit comprising a dynamic random access memory circuit disposed on said die and having a plurality of memory cells;
said integrated circuit further including a refresh signal generation circuit disposed on said die and adapted to refresh said memory cells in response to trigger signals, a self timer circuit adapted to provide a plurality of refresh trigger signals at a first rate;
a port disposed on said die and adapted to receive a plurality of refresh trigger signals from said external timer circuit; and
a timer selection circuit disposed on said die and adapted to, in response to a test mode enable signal, disconnect said self timer circuit from said refresh generation circuit during a test refresh mode, and to couple refresh trigger signals from said port to said refresh generation circuit, wherein said refresh signal generation circuit is adapted to refresh said memory cells at a second test mode rate in response to refresh trigger signals provided by said timer circuit external to said die during said test refresh mode. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification