
10
S25FL Family (Serial Peripheral Interface) S25FL004A
S25FL004A_00_A1 March 28, 2005
A d v a n c e  I n f o r m a t i o n
Operating Features
All device data into and out, is shifted in 8-bit chunks.
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. 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, or Bulk Erase
The Page Program (PP) instruction allows bits to be programmed from 1 to 0. Be-
fore this can be applied, the memory bytes need to be first erased to all 1’s (FFh) 
before any programming. This can be achieved in two ways: 
 A sector at a time using the Sector Erase (SE) instruction
 The entire memory, using the Bulk Erase (BE) 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. The 
Write in Progress (WIP) bit is provided in the Status Register so that the applica-
tion program can monitor its value, polling it to establish when the previous Write 
cycle, Program cycle, or Erase cycle is complete.
Active Power and Standby Power 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 into the Standby Power 
mode. The device consumption drops to I
SB
. This can be used as an extra Deep 
Power Down on mechanism, when the device is not in active use, to protect the 
device from inadvertent Write, Program, or Erase instructions. 
Status Register
The Status Register contains a number of status and control bits, as shown in 
Figure 7, on page 17
 that can be read or set (as appropriate) by specific 
instructions
 WIP bit:
 The Write In Progress (WIP) bit indicates whether the memory is 
busy with a Write Status Register, Program or Erase cycle.
 WEL bit:
 The Write Enable Latch (WEL) bit indicates the internal Write Enable 
Latch status.
 BP2, BP1, BP0 bits:
 The Block Protect (BP2, BP1, BP0) bits are non-volatile. 
They define the area size to be software protected against Program and Erase 
instructions.
 SRWD bit:
 The Status Register Write Disable (SRWD) bit is operated in con-
junction with the Write Protect (W#) signal. The Status Register Write Disable 
(SRWD) bit and Write Protect (W#) signal allow the device to be put in the 
Hardware Protected mode. In this mode, the Status Register’s non-volatile 
bits (SRWD, BP2, BP1, BP0) become read-only bits.