FM25C160B(2014) Ver la hoja de datos (PDF) - Cypress Semiconductor
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FM25C160B Datasheet PDF : 20 Pages
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FM25C160B
Figure 8. RDSR Bus Configuration
CS
SCK
SI
SO
0 1 2 3 4 5 6 7 01 2 3 4 5 67
Opcode
000001 01 0
HI-Z
Data
D7 D6 D5 D4 D3 D2 D1 D0
MSB
LSB
Figure 9. WRSR Bus Configuration (WREN not shown)
CS
SCK
SI
SO
01 23 4 5 6 701 2 3 4 5 6 7
Opcode
Data
0 0 0 0 0 0 0 1 D7 X X X D3 D2 X X
MSB
LSB
HI-Z
Memory Operation
The SPI interface, which is capable of a high clock frequency,
highlights the fast write capability of the F-RAM technology.
Unlike serial flash and EEPROMs, the FM25C160B can perform
sequential writes at bus speed. No page register is needed and
any number of sequential writes may be performed.
Write Operation
All writes to the memory begin with a WREN opcode. The WRITE
opcode is followed by a two-byte address containing the 11-bit
address (A10-A0) of the first data byte to be written into the
memory. The upper five bits of the two-byte address are ignored.
Subsequent bytes are data bytes, which are written sequentially.
Addresses are incremented internally as long as the bus master
continues to issue clocks and keeps CS LOW. If the last address
of 7FFh is reached, the counter will roll over to 000h. Data is
written MSB first. The rising edge of CS terminates a write
operation. A write operation is shown in Figure 10.
Note When a burst write reaches a protected block address, the
automatic address increment stops and all the subsequent data
bytes received for write will be ignored by the device.
EEPROMs use page buffers to increase their write throughput.
This compensates for the technology's inherently slow write
operations. F-RAM memories do not have page buffers because
each byte is written to the F-RAM array immediately after it is
clocked in (after the eighth clock). This allows any number of
bytes to be written without page buffer delays.
Note If the power is lost in the middle of the write operation, only
the last completed byte will be written.
Read Operation
After the falling edge of CS, the bus master can issue a READ
opcode. Following the READ command is a two-byte address
containing the 11-bit address (A10-A0) of the first byte of the read
operation. The upper five bits of the address are ignored. After
the opcode and address are issued, the device drives out the
read data on the next eight clocks. The SI input is ignored during
read data bytes. Subsequent bytes are data bytes, which are
read out sequentially. Addresses are incremented internally as
long as the bus master continues to issue clocks and CS is LOW.
If the last address of 7FFh is reached, the counter will roll over
to 000h. Data is read MSB first. The rising edge of CS terminates
a read operation and tristates the SO pin. A read operation is
shown in Figure 11.
Document Number: 001-86150 Rev. *A
Page 8 of 20
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