S29AS016J datasheet(28/59 Pages) CYPRESS

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Document Number: 002-01122 Rev.*L

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S29AS016J

10.4

Enter Secured Silicon Sector/Exit Secured Silicon Sector Command

Sequence

The Secured Silicon Sector region provides a secured data area containing a random, sixteen-byte electronic serial number (ESN).

The system can access the Secured Silicon Sector region by issuing the three-cycle Enter Secured Silicon Sector command

sequence. The device continues to access the Secured Silicon Sector region until the system issues the four-cycle Exit Secured

Silicon Sector command sequence. The Exit Secured Silicon Sector command sequence returns the device to normal operation.

Table shows the addresses and data requirements for both command sequences. Note that the unlock bypass mode is not

available when the device enters the Secured Silicon Sector. For further information, see Secured Silicon Sector Flash Memory

Region on page 21.

10.5

Word/Byte Program Command Sequence

The system may program the device by word or byte, depending on the state of the BYTE# pin. Programming is a four-bus-cycle

operation. The program command sequence is initiated by writing two unlock write cycles, followed by the program set-up

command. The program address and data are written next, which in turn initiate the Embedded Program algorithm. The system is

not required to provide further controls or timings. The device automatically generates the program pulses and verifies the

programmed cell margin. Table on page 32 shows the address and data requirements for the byte program command sequence.

When the Embedded Program algorithm is complete, the device then returns to reading array data and addresses are no longer

latched. The system can determine the status of the program operation by using DQ7, DQ6, or RY/BY#. See Write Operation Status

on page 36 for information on these status bits.

Any commands written to the device during the Embedded Program Algorithm are ignored. Note that a hardware reset immediately

terminates the programming operation. The Byte Program command sequence should be reinitiated once the device has reset to

reading array data, to ensure data integrity.

Programming is allowed in any sequence and across sector boundaries. A bit cannot be programmed from a 0 back to a 1.

Attempting to do so may halt the operation and set DQ5 to 1, or cause the Data# Polling algorithm to indicate the operation was

successful. However, a succeeding read will show that the data is still 0. Only erase operations can convert a 0 to a 1.

10.6

Unlock Bypass Command Sequence

The unlock bypass feature allows the system to program bytes or words to the device faster than using the standard program

command sequence. The unlock bypass command sequence is initiated by first writing two unlock cycles. This is followed by a third

write cycle containing the unlock bypass command, 20h. The device then enters the unlock bypass mode. A two-cycle unlock

bypass program command sequence is all that is required to program in this mode. The first cycle in this sequence contains the

unlock bypass program command, A0h; the second cycle contains the program address and data. Additional data is programmed in

the same manner. This mode dispenses with the initial two unlock cycles required in the standard program command sequence,

resulting in faster total programming time. Table on page 32 shows the requirements for the command sequence.

During the unlock bypass mode, only the Unlock Bypass Program and Unlock Bypass Reset commands are valid. To exit the unlock

bypass mode, the system must issue the two-cycle unlock bypass reset command sequence. The first cycle must contain the data

90h; the second cycle the data F0h. Addresses are don’t care for both cycles. The device then returns to reading array data.

Figure 10.1 on page 29 illustrates the algorithm for the program operation. See Erase/Program Operations on page 47 for

parameters, and to Figure 18.5 on page 48 for timing diagrams.

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