Apparatus and method for determining a read level of a flash memory after an inactive period of time

A control circuit for determining a dwell time in a memory circuit after a shutdown of the memory circuit, comprising:

• a memory interface configured to be operably coupled to the memory circuit;
• and
• a controller, wherein the controller is configured to:
• store a first test block before the shutdown;
• save a second test block after the memory circuit is powered on;
• perform a first read level sweep of the first test block to determine a first read level voltage with minimum errors, including determining the first read level voltage as a function of a nominal read level voltage and a first estimation parameter;
• perform a second read level sweep of the second test block to determine a second read level voltage with minimum errors, including determining the second read level voltage as a function of the nominal read level voltage and a second estimation parameter;
• calculate a shutdown VT shift as a function of the first read level voltage and the second read level voltage;
• and
• calculate a shutdown duration as a function of the shutdown VT shift.

A system for determining a dwell time in a memory circuit after a shutdown of the memory circuit, comprising:

• a host interface configured to be operably coupled to a host device, to receive data from the host device, and to send data to the host device;
• a temperature sensor;
• a storage medium interface operably coupled to a volatile memory;
• a memory interface operably coupled to the memory circuit;
• and
• a controller operably coupled to the host interface, wherein the controller is operable to:
• store a first test block on the memory circuit before the shutdown;
• store a second test block on the memory circuit after the memory circuit is powered on;
• perform a first read level sweep of the first test block to determine a first read level voltage with minimum errors, including determining the first read level voltage as a function of a nominal read level voltage and a first estimation parameter;
• perform a second read level sweep of the second test block to determine a second read level voltage with minimum errors, including determining the second read level voltage as a function of the nominal read level voltage and a second estimation parameter;
• calculate a shutdown VT shift as a function of the first read level voltage and the second read level voltage;
• and
• calculate a shutdown duration as a function of the shutdown VT shift.