S29AS016J datasheet(32/60 Pages) SPANSION

32 / 60 page

S29AS016J

S29AS016J_00_11 February 1, 2012

Da ta

Sh e e t

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 11.1 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 26.

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 11.1

on page 36 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 38 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 11.1 on page 36 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 33 illustrates the algorithm for the program operation. See Erase/Program Operations

on page 49 for parameters, and to Figure 18.5 on page 49 for timing diagrams.

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