W25B40 Datasheet, PDF (19/36 Pages) Winbond – 4M-BIT SERIAL FLASH MEMORY WITH BOOT AND PARAMETER SECTORS

W25B40/W25B40A
8.2.9 Page Program (02h)
The Page Program instruction allows from one byte to 256 bytes of data to be programmed at memory
locations previously erased to all 1s (FFh). A Write Enable instruction must be executed before the
device will accept the Page Program Instruction (Status Register bit WEL must equal 1). The
instruction is initiated by driving the /CS pin low then shifting the instruction code “02h” followed by a
24-bit address (A23-A0) and at least one data byte, into the DI pin. The /CS pin must be driven low for
the entire length of the instruction while data is being sent to the device. The Page Program instruction
sequence is shown in figure 10.
If an entire 256 byte page is to be programmed, the last address byte (the 8 least significant address
bits) should be set to 0. If the last address byte is not zero, and the number of clocks exceed the
remaining page length, the addressing will wrap to the beginning of the page. Less than 256 bytes can
be programmed without having any effect on other bytes within the same page. If more than 256 bytes
are sent to the device the addressing will wrap to the beginning of the page and overwrite previously
sent data.
As with the write and erase instructions, the /CS pin must be driven high after the eighth bit of the last
byte has been latched. If this is not done the Page Program instruction will not be executed. After /CS
is driven high, the self-timed Page Program instruction will commence for a time duration of tpp (See
AC Characteristics). While the Page Program cycle is in progress, the Read Status Register
instruction may still be accessed for checking the status of the BUSY bit. The BUSY bit is a 1 during
the Page Program cycle and becomes a 0 when the cycle is finished and the device is ready to accept
other instructions again. After the Page Program cycle has finished the Write Enable Latch (WEL) bit
in the Status Register is cleared to 0. The Page Program instruction will not be executed if the
addressed page is protected by the Block Protect (BP2, BP1, BP0) bits (see Write Protection
Operation table).
Figure 10. Page Program Instruction Sequence Diagram
- 19 -
Publication Release Date: January 6, 2006
Revision M