W39V040C

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6.6

Sector/Page Erase Command

Sector/Page erase is a six-bus cycles operation. There are two "unlock" write cycles, followed by

writing the "set-up" command. Two more "unlock" write cycles then follows by the Sector/Page erase

command. The Sector/Page address (any address location within the desired Sector/Page) is latched

on the rising edge of R/#C in programmer mode, while the command (30H/50H) is latched on the rising

edge of #WE.

Sector/Page erase does not require the user to program the device prior to erase. When erasing a

Sector/ Page, the remaining unselected sectors/ Pages are not affected. The system is not required to

provide any controls or timings during these operations.

The automatic Sector/ Page erase begins after the erase command is completed, right from the rising

edge of the #WE pulse for the last Sector/ Page erase command pulse and terminates when the data

on DQ7, Data Polling, is "1" at which time the device returns to the read mode. Data Polling must be

performed at an address within any of the sectors/page being erased.

Refer to the Erase Command flow Chart using typical command strings and bus operations.

6.7

Program Operation

The W39V040C is programmed on a byte-by-byte basis. Program operation can only change logical

data "1" to logical data "0." The erase operation, which changed entire data in main memory and/or

boot block from "0" to "1", is needed before programming.

The program operation is initiated by a 4-byte command cycle (see Command Codes for Byte

Programming). The device will internally enter the program operation immediately after the

byte-program command is entered. The internal program timer will automatically time-out (10

μS typ. -

used to detect end of program cycle.

6.8

Hardware Data Protection

　 The integrity of the data stored in the W39V040C is also hardware protected in the following ways:

(1) Noise/Glitch Protection: A #WE pulse of less than 5 nS in duration will not initiate a write cycle.

less than 2.0V typical.

(3) Write Inhibit Mode: Forcing #OE low or #WE high will inhibit the write operation. This prevents

inadvertent writes during power-up or power-down periods.

6.9

Write operation status

The device provides several bits to determine the status of a program or erase operation: DQ5, DQ6,

and DQ7. Each of DQ7 and DQ6 provides a method for determining whether a program or erase

operation is complete or in progress. The device also offers a hardware-based output signal, RY/#BY in

programmer mode, to determine whether an Embedded Program or Erase operation is in progress or

has been completed.