EN25B64 Datasheet, PDF (11/37 Pages) Eon Silicon Solution Inc. – 64 Megabit Serial Flash Memory with Boot and Parameter Sectors

EN25B64
OPERATING FEATURES
SPI Modes
The EN25B64 is accessed through an SPI compatible bus consisting of four signals: Serial Clock
(CLK), Chip Select (CS#), Serial Data Input (DI) and Serial Data Output (DO). Both SPI bus
operation Modes 0 (0,0) and 3 (1,1) are supported. The primary difference between Mode 0 and
Mode 3, as shown in Figure 3, concerns the normal state of the CLK signal when the SPI bus
master is in standby and data is not being transferred to the Serial Flash. For Mode 0 the CLK signal
is normally low. For Mode 3 the CLK signal is normally high. In either case data input on the DI pin is
sampled on the rising edge of the CLK. Data output on the DO pin is clocked out on the falling edge
of CLK.
Figure 3. SPI Modes
Page Programming
To program one data byte, two instructions are required: Write Enable (WREN), which is one byte,
and a Page Program (PP) sequence, which consists of four bytes plus data. This is followed by the
internal Program cycle (of duration t_PP).
To spread this overhead, the Page Program (PP) instruction allows up to 256 bytes to be pro-
grammed at a time (changing bits from 1 to 0), provided that they lie in consecutive addresses on
the same page of memory.
Sector Erase and Bulk Erase
The Page Program (PP) instruction allows bits to be reset from 1 to 0. Before this can be applied,
the bytes of memory need to have been erased to all 1s (FFh). This can be achieved either a sector
at a time, using the Sector Erase (SE) instruction, or throughout the entire memory, using the Bulk
Erase (BE) instruction. This starts an internal Erase cycle (of duration t_SE or t_BE). The Erase
instruction must be preceded by a Write Enable (WREN) instruction.
Polling During a Write, Program or Erase Cycle
A further improvement in the time to Write Status Register (WRSR), Program (PP) or Erase (SE or
BE) can be achieved by not waiting for the worst case delay (t_W, t_PP, t_SE, or t_BE). The Write In
Progress (WIP) bit is provided in the Status Register so that the application program can monitor its
value, polling it to establish when the previous Write cycle, Program cycle or Erase cycle is complete.
Active Power, Stand-by Power and Deep Power-Down Modes
When Chip Select (CS#) is Low, the device is enabled, and in the Active Power mode. When Chip
Select (CS#) is High, the device is disabled, but could remain in the Active Power mode until all
internal cycles have completed (Program, Erase, Write Status Register). The device then goes in to
the Stand-by Power mode. The device consumption drops to I_CC1.
The Deep Power-down mode is entered when the specific instruction (the Enter Deep Power-down
Mode (DP) instruction) is executed. The device consumption drops further to I_CC2. The device re-
mains in this mode until another specific instruction (the Release from Deep Power-down Mode and
Read Device ID (RDI) instruction) is executed.
This Data Sheet may be revised by subsequent versions ₁₁ ©2004 Eon Silicon Solution, Inc., www.essi.com.tw
or modifications due to changes in technical specifications.
Rev. C, Issue Date: 2008/06/23