D A T A S H E E T
Address 3Fh (or Offset from 3Fh by a Multiple of 64),”
Simultaneous Read/Write Operations with
Zero Latency
on page 62, Figure 25, “Standard Handshake Burst
Suspend Prior to Initial Access,” on page 63, Figure 26,
“Standard Handshake Burst Suspend at or after Initial
Access,” on page 63, Figure 27, “Standard Handshake
Burst Suspend at Address 3Fh (Starting Address 3Dh
or Earlier),” on page 64, Figure 28, “Standard Hand-
shake Burst Suspend at Address 3Eh/3Fh (Without a
Valid Initial Access),” on page 64, and Figure 29, “Stan-
dard Handshake Burst Suspend at Address 3Eh/3Fh
(with 1 Access CLK),” on page 65.
This device is capable of reading data from one bank of
memory while programming or erasing in another bank
of memory. An erase operation may also be suspended
to read from or program to another location within the
same bank (except the sector being erased).
Figure 49, “Back-to-Back Read/Write Cycle Timings,”
on page 83 shows how read and write cycles may be
initiated for simultaneous operation with zero latency.
Refer to the DC Characteristics table for
read-while-program and read-while-erase current
specifications.
Burst plus Burst Suspend should not last longer than
t
without re-latching an address or crossing an
RCC
address boundary. To resume the burst access, OE#
must be re-asserted. The next active CLK edge will
resume the burst sequence where it had been sus-
pended. See Figure 30, “Read Cycle for Continuous
Suspend,” on page 65.
Writing Commands/Command Sequences
The device has the capability of performing an asyn-
chronous or synchronous write operation. While the
device is configured in Asynchronous read it is able to
perform Asynchronous write operations only. CLK is
ignored in the Asynchronous programming mode.
When in the Synchronous read mode configuration, the
device is able to perform both Asynchronous and Syn-
chronous write operations. CLK and WE# address
latch is supported in the Synchronous programming
mode. During a synchronous write operation, to write a
command or command sequence (which includes pro-
gramming data to the device and erasing sectors of
The RDY pin is only controlled by CE#. RDY will remain
active and is not placed into a high-impedance state
when OE# is de-asserted.
Configuration Register
The device uses a configuration register to set the
various burst parameters: number of wait states, burst
read mode, active clock edge, RDY configuration, and
synchronous mode active.
memory), the system must drive AVD# and CE# to V ,
IL
and OE# to V when providing an address to the
IH
Reduced Wait-state Handshaking Option
device, and drive WE# and CE# to V , and OE# to V
IL
IH
The device can be equipped with a reduced wait-state
handshaking feature that allows the host system to
simply monitor the RDY signal from the device to deter-
mine when the initial word of burst data is ready to be
read. The host system should use the programmable
wait state configuration to set the number of wait states
for optimal burst mode operation. The initial word of
burst data is indicated by the rising edge of RDY after
OE# goes low.
when writing commands or data. During an asynchro-
nous write operation, the system must drive CE# and
WE# to V and OE# to V when providing an address,
IL
IH
command, and data. Addresses are latched on the last
falling edge of WE# or CE#, while data is latched on the
1st rising edge of WE# or CE#. The asynchronous and
synchronous programing operation is independent of
the Set Device Read Mode bit in the Configuration
Register (see Table 18, “Configuration Register,” on
page 36).
The presence of the reduced wait-state handshaking
feature may be verified by writing the autoselect
command sequence to the device. See “Autoselect
Command Sequence” for details.
The device features an Unlock Bypass mode to facili-
tate faster programming. Once the device enters the
Unlock Bypass mode, only two write cycles are
required to program a word, instead of four.
For optimal burst mode performance on devices
without the reduced wait-state handshaking option, the
host system must set the appropriate number of wait
states in the flash device depending on clock frequency
and the presence of a boundary crossing. See “Set
Configuration Register Command Sequence” section
on page 33 section for more information. The device
will automatically delay RDY and data by one additional
clock cycle when the starting address is odd.
An erase operation can erase one sector, multiple sec-
tors, or the entire device. Table 12, “Am29BDS128H
Sector Address Table,” on page 27 indicates the
address space that each sector occupies. The device
address space is divided into four banks: Banks B and
C contain only 32 Kword sectors, while Banks A and D
contain both 4 Kword boot sectors in addition to 32
Kword sectors. A “bank address” is the address bits
required to uniquely select a bank. Similarly, a “sector
address” is the address bits required to uniquely select
a sector.
The autoselect function allows the host system to
determine whether the flash device is enabled for
reduced wait-state handshaking. See the “Autoselect
Command Sequence” section for more information.
May 10, 2006 27024B3
Am29BDS128H/Am29BDS640H
13
SPANSION [ SPANSION ]
