| US 7,457,178 B2 | ||
| Trimming of analog voltages in flash memory devices | ||
| Loc Tu, San Jose, Calif. (US); Jeffrey Lutze, San Jose, Calif. (US); Jun Wan, Sunnyvale, Calif. (US); and Jian Chen, Sunnyvale, Calif. (US) | ||
| Assigned to SanDisk Corporation, Milpitas, Calif. (US) | ||
| Filed on Jan. 12, 2006, as Appl. No. 11/331,479. | ||
| Prior Publication US 2007/0159891 A1, Jul. 12, 2007 | ||
| Int. Cl. G11C 29/00 (2006.01) | ||
| U.S. Cl. 365—201 [365/185.18; 365/185.24] | 11 Claims |
| 1. A method of trimming an analog voltage in a flash memory device, comprising the steps of:
issuing a first command to place the flash memory device into a test mode, a terminal of the flash memory device has a test
function when in the test mode;
measuring a threshold voltage of at least one non-volatile memory cell by applying a control gate voltage at the terminal
of the flash memory device while in the test mode;
operating an analog voltage generator circuit at a plurality of output analog voltage levels to access the at least one memory
cell while in the test mode;
responsive to the measuring and operating steps, setting the output analog voltage level of the analog voltage generator circuit
for use in normal operation of the flash memory device; and
issuing a second command to place the flash memory device into a normal operating mode after the setting the output analog
voltage level of the analog voltage generator circuit for use in normal operation;
wherein the terminal has an operating function in the normal operating mode.
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