Method for improving performance when flash memory storage device works in wide temperature range
A method of a flash memory storage device using Read Retry method is disclosed. This method includes using a thermal sensor to records temperature information while programming flash memory, and using this temperature information to compensate the temperature difference between program and read operation to improve Read Retry performance.
1. A method for improving performance when a flash memory storage device works in a wide temperature range, the steps comprising:
step SA 01 : received a read CMD;
step SA 02 : read data from a NAND flash memory;
step SA 03 : judging if the cyclic Codes match; if yes, terminates the process; if no, runs to next step;
step SA 04 : checking if an ECC engine can correct; if yes, the ECC engine starts to correct; if no, runs to next step;
step SA 04 ′: getting a current temperature and a programming temperature from a thermal sensor;
step SA 05 : checking a Read Retry Record table; check if a physical address has ever applied a Read Retry method and has proper start test voltage record; if yes, jumps to next two step; if no, runs to next step;
step SA 06 : calculating a Read Retry start test voltage according to the current temperature and the programming temperature;
step SA 07 : applying the Read Retry start test voltage to a memory cell array;
step SA 08 : reading data from the NAND flash memory;
step SA 09 : judging if the Cyclic Codes match; if yes, saves the current test voltage to the Read Retry Record table; if no, runs to next step;
step SA 10 : checking if the ECC engine can correct; if yes, runs to step SA 04 ; if no, runs to next step; and
step SA 11 : checking if all available test voltages are tried; if yes, reports an uncorrectable error; if no, applying another test voltage and loops to step SA 08 .
2. The method as claimed in claim 1 , wherein the thermal sensor is disposed inside or outside the NAND flash memory.