S29GL032A datasheet(39/88 Pages) SPANSION

39 / 88 page

January 28, 2005 S29GLxxxA_00_A2

S29GLxxxA MirrorBit™ Flash Family

Advance

Information

Figure 2, except that RESET# may be at either VIH or VID. This allows in-sys-

tem protection of the Secured Silicon Sector without raising any device pin to

a high voltage. Note that this method is only applicable to the Secured Silicon

Sector.

Write the three-cycle Enter Secured Silicon Sector Region command se-

quence, and then use the alternate method of sector protection described in

the “Sector Group Protection and Unprotection” section.

Once the Secured Silicon Sector is programmed, locked and verified, the system

must write the Exit Secured Silicon Sector Region command sequence to return

to reading and writing within the remainder of the array.

Factory Locked: Secured Silicon Sector Programmed and

Protected At the Factory

In devices with an ESN, the Secured Silicon Sector is protected when the device

is shipped from the factory. The Secured Silicon Sector cannot be modified in any

way. An ESN Factory Locked device has an 16-byte random ESN at addresses

000000h–000007h. Please contact your sales representative for details on order-

ing ESN Factory Locked devices.

Customers may opt to have their code programmed by the factory through the

Spansion programming service (Customer Factory Locked). The devices are then

shipped from the factory with the Secured Silicon Sector permanently locked.

Contact your sales representative for details on using the Spansion programming

service.

Write Protect (WP#)

The Write Protect function provides a hardware method of protecting the first or

last sector group without using VID. Write Protect is one of two functions provided

by the WP#/ACC input.

If the system asserts VIL on the WP#/ACC pin, the device disables program and

erase functions in the first or last sector group independently of whether those

sector groups were protected or unprotected. Note that if WP#/ACC is at VIL

when the device is in the standby mode, the maximum input load current is in-

creased. See the table in “DC Characteristics” section on page 65.

If the system asserts VIH on the WP#/ACC pin, the device reverts to

whether the first or last sector was previously set to be protected or un-

protected using the method described in “Sector Group Protection and

Unprotection”. Note that WP# has an internal pullup; when uncon-

nected, WP# is at VIH.

Hardware Data Protection

The command sequence requirement of unlock cycles for programming or erasing

provides data protection against inadvertent writes (refer to Table 25 and Table

26 for command definitions). In addition, the following hardware data protection

measures prevent accidental erasure or programming, which might otherwise be

caused by spurious system level signals during VCC power-up and power-down

transitions, or from system noise.

Low VCC Write Inhibit

When VCC is less than VLKO, the device does not accept any write cycles. This pro-

tects data during VCC power-up and power-down. The command register and all

internal program/erase circuits are disabled, and the device resets to the read

S29GL032A Datasheet(PDF) 39 Page - SPANSION

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