FM33256B-G Cypress Semiconductor, FM33256B-G Datasheet - Page 21

• Manufacturer Part Number: FM33256B-G
• Description: Real Time Clock 256Kb F-RAM Processor Companion
• Manufacturer: Cypress Semiconductor

Specifications of FM33256B-G

• Rohs: yes
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-14
• Factory Pack Quantity: 56

RDSR – Read Status Register
The RDSR command allows the bus master to verify
the contents of the Status Register. Reading this
register provides information about the current state
of the write protection bits. Following the RDSR op-
code, the FM33256B will return one byte with the
contents of the Status Register. The Status Register
is described in detail in a later section.
RDPC – Read Processor Companion
The RDPC command allows the bus master to verify
the contents of the Processor Companion registers.
Following the RDPC op-code, a single-byte register
address is sent. The FM33256B will then return one
This product conforms to specifications per the terms of the Ramtron
standard warranty. The product has completed Ramtron’s internal
qualification testing and has reached production status.
Rev. 3.0
Aug. 2012
SCK
SO
CS
SI
0
0
0
Figure 19. WRSR Bus Configuration
Figure 17. WRDI Bus Configuration
Figure 18. RDSR Bus Configuration
1
(WREN must precede WRSR)
0
2
0
Hi-Z
3
0
4
WRSR – Write Status Register
The WRSR command allows the user to select
certain write protection features by writing a byte to
the Status Register. Prior to sending the WRSR
command, the user must send a WREN command to
enable writes. Note that executing a WRSR
command is a write operation and therefore clears
the Write Enable Latch. The bus timings of RDSR
and WRSR are shown below.
or more bytes with the contents of the companion
registers. When reading multiple data bytes, the
nternal register address will wrap around to 00h after
1Dh is reached.
1
5
1850 Ramtron Drive, Colorado Springs, CO 80921
FM33256B SPI Companion w/ FRAM
0
6
Ramtron International Corporation
0
7
(800) 545-FRAM, [phone]
www.ramtron.com
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