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THIS SPEC IS OBSOLETE
Spec No: 001-84500
Spec Title: FM25V20, 2-MBIT (256 K X 8) SERIAL (SPI) FRAM
Sunset Owner: Girija Chougala (GVCH)
Replaced by: NONE
FM25V20
2-Mbit (256 K × 8) Serial (SPI) F-RAM
2-Mbit (256 K × 8) Serial (SPI) F-RAM
Features
Functional Overview
■
2-Mbit ferroelectric random access memory (F-RAM) logically
organized as 256 K × 8
14
❐ High-endurance 100 trillion (10 ) read/writes
❐ 151-year data retention (See the Data Retention and Endurance table)
❐ NoDelay™ writes
❐ Advanced high-reliability ferroelectric process
The FM25V20 is a 2-Mbit nonvolatile memory employing an
advanced ferroelectric process. A ferroelectric random access
memory or F-RAM is nonvolatile and performs reads and writes
similar to a RAM. It provides reliable data retention for 151 years
while eliminating the complexities, overhead, and system-level
reliability problems caused by serial flash, EEPROM, and other
nonvolatile memories.
■
Very fast serial peripheral interface (SPI)
❐ Up to 40-MHz frequency
❐ Direct hardware replacement for serial flash and EEPROM
❐ Supports SPI mode 0 (0, 0) and mode 3 (1, 1)
■
Sophisticated write protection scheme
❐ Hardware protection using the Write Protect (WP) pin
❐ Software protection using Write Disable instruction
❐ Software block protection for 1/4, 1/2, or entire array
■
Device ID
❐ Manufacturer ID and Product ID
Unlike serial flash and EEPROM, the FM25V20 performs write
operations at bus speed. No write delays are incurred. Data is
written to the memory array immediately after each byte is
successfully transferred to the device. The next bus cycle can
commence without the need for data polling. In addition, the
product offers substantial write endurance compared with other
nonvolatile memories. The FM25V20 is capable of supporting
1014 read/write cycles, or 100 million times more write cycles
than EEPROM.
■
Low power consumption
❐ 300 A active current at 1 MHz
❐ 100 A (typ) standby current
❐ 3 A sleep mode current
■
Low-voltage operation: VDD = 2.0 V to 3.6 V
■
Industrial temperature –40 C to +85 C
■
Packages
❐ 8-pin small outline integrated circuit (SOIC) package
❐ 8-pin thin dual flat no leads (TDFN) package
■
Restriction of hazardous substances (RoHS) compliant
These capabilities make the FM25V20 ideal for nonvolatile
memory applications, requiring frequent or rapid writes.
Examples range from data collection, where the number of write
cycles may be critical, to demanding industrial controls where the
long write time of serial flash or EEPROM can cause data loss.
The FM25V20 provides substantial benefits to users of serial
EEPROM or flash as a hardware drop-in replacement. The
FM25V20 uses the high-speed SPI bus, which enhances the
high-speed write capability of F-RAM technology. The device
incorporates a read-only Device ID that allows the host to
determine the manufacturer, product density, and product
revision. The device specifications are guaranteed over an
industrial temperature range of –40 C to +85 C.
For a complete list of related documentation, click here.
Logic Block Diagram
WP
Instruction Decoder
Clock Generator
Control Logic
Write Protect
CS
HOLD
SCK
256 K x 8
F-RAM Array
Instruction Register
Address Register
Counter
18
SI
8
Data I/O Register
SO
3
Nonvolatile Status
Register
Cypress Semiconductor Corporation
Document Number: 001-84500 Rev. *G
•
198 Champion Court
•
San Jose, CA 95134-1709
•
408-943-2600
Revised June 2, 2015
FM25V20
Contents
Pinouts .............................................................................. 3
Pin Definitions .................................................................. 3
Overview ............................................................................ 4
Memory Architecture ........................................................ 4
Serial Peripheral Interface – SPI Bus .............................. 4
SPI Overview ............................................................... 4
SPI Modes ................................................................... 5
Power Up to First Access ............................................ 6
Command Structure .................................................... 6
WREN - Set Write Enable Latch ................................. 6
WRDI - Reset Write Enable Latch ............................... 6
Status Register and Write Protection ............................. 7
RDSR - Read Status Register ..................................... 8
WRSR - Write Status Register .................................... 8
Memory Operation ............................................................ 8
Write Operation ........................................................... 8
Read Operation ........................................................... 9
Fast Read Operation ................................................... 9
HOLD Pin Operation ................................................. 10
Sleep Mode ............................................................... 11
Device ID ................................................................... 11
Endurance ................................................................. 12
Document Number: 001-84500 Rev. *G
Maximum Ratings ........................................................... 13
Operating Range ............................................................. 13
DC Electrical Characteristics ........................................ 13
Data Retention and Endurance ..................................... 14
Capacitance .................................................................... 14
Thermal Resistance ........................................................ 14
AC Test Conditions ........................................................ 14
AC Switching Characteristics ....................................... 15
Power Cycle Timing ....................................................... 17
Ordering Information ...................................................... 18
Ordering Code Definitions ......................................... 18
Package Diagrams .......................................................... 19
Acronyms ........................................................................ 21
Document Conventions ................................................. 21
Units of Measure ....................................................... 21
Document History Page ................................................. 22
Sales, Solutions, and Legal Information ...................... 24
Worldwide Sales and Design Support ....................... 24
Products .................................................................... 24
PSoC® Solutions ...................................................... 24
Cypress Developer Community ................................. 24
Technical Support ..................................................... 24
Page 2 of 24
FM25V20
Pinouts
Figure 1. 8-pin SOIC pinout
CS
1
SO
2
WP
3
VSS
4
Top View
not to scale
8
VDD
7
HOLD
6
SCK
5
SI
Figure 2. 8-pin TDFN pinout
CS
1
SO
2
WP
3
VSS
4
EXPOSED
PAD
8
VDD
7
HOLD
6
SCK
5
SI
Top View
not to scale
Pin Definitions
Pin Name
I/O Type
Description
CS
Input
Chip Select. This active LOW input activates the device. When HIGH, the device enters low-power
standby mode, ignores other inputs, and the output is tristated. When LOW, the device internally
activates the SCK signal. A falling edge on CS must occur before every opcode.
SCK
Input
Serial Clock. All I/O activity is synchronized to the serial clock. Inputs are latched on the rising
edge and outputs occur on the falling edge. Because the device is synchronous, the clock
frequency may be any value between 0 and 40 MHz and may be interrupted at any time.
SI[1]
Input
Serial Input. All data is input to the device on this pin. The pin is sampled on the rising edge of
SCK and is ignored at other times. It should always be driven to a valid logic level to meet IDD
specifications.
SO[1]
Output
Serial Output. This is the data output pin. It is driven during a read and remains tristated at all
other times including when HOLD is LOW. Data transitions are driven on the falling edge of the
serial clock.
WP
Input
Write Protect. This Active LOW pin prevents write operation to the Status Register when WPEN
is set to ‘1’. This is critical because other write protection features are controlled through the Status
Register. A complete explanation of write protection is provided in “Status Register and Write
Protection” on page 7. This pin must be tied to VDD if not used.
HOLD
Input
HOLD Pin. The HOLD pin is used when the host CPU must interrupt a memory operation for
another task. When HOLD is LOW, the current operation is suspended. The device ignores any
transition on SCK or CS. All transitions on HOLD must occur while SCK is LOW. This pin must be
tied to VDD if not used.
VSS
Power supply Ground for the device. Must be connected to the ground of the system.
VDD
Power supply Power supply inputs to the device.
EXPOSED PAD
No connect
The EXPOSED PAD on the bottom of 8-pin TDFN package is not connected to the die. The
EXPOSED PAD should be left floating.
Note
1. SI may be connected to SO for a single pin data interface.
Document Number: 001-84500 Rev. *G
Page 3 of 24
FM25V20
Overview
The FM25V20 is a serial F-RAM memory. The memory array is
logically organized as 262,144 × 8 bits and is accessed using an
industry-standard serial peripheral interface (SPI) bus. The
functional operation of the F-RAM is similar to serial flash and
serial EEPROMs. The major difference between the FM25V20
and a serial flash or EEPROM with the same pinout is the
F-RAM's superior write performance, high endurance, and low
power consumption.
Memory Architecture
When accessing the FM25V20, the user addresses 256K
locations of eight data bits each. These eight data bits are shifted
in or out serially. The addresses are accessed using the SPI
protocol, which includes a chip select (to permit multiple devices
on the bus), an opcode, and a three-byte address. The upper 6
bits of the address range are 'don't care' values. The complete
address of 18 bits specifies each byte address uniquely.
Most functions of the FM25V20 are either controlled by the SPI
interface or handled by on-board circuitry. The access time for
the memory operation is essentially zero, beyond the time
needed for the serial protocol. That is, the memory is read or
written at the speed of the SPI bus. Unlike a serial flash or
EEPROM, it is not necessary to poll the device for a ready
condition because writes occur at bus speed. By the time a new
bus transaction can be shifted into the device, a write operation
is complete. This is explained in more detail in the interface
section.
Serial Peripheral Interface – SPI Bus
The FM25V20 is a SPI slave device and operates at speeds up
to 40 MHz. This high-speed serial bus provides
high-performance serial communication to a SPI master. Many
common microcontrollers have hardware SPI ports allowing a
direct interface. It is quite simple to emulate the port using
ordinary port pins for microcontrollers that do not. The FM25V20
operates in SPI Mode 0 and 3.
SPI Overview
The SPI is a four-pin interface with Chip Select (CS), Serial Input
(SI), Serial Output (SO), and Serial Clock (SCK) pins.
The SPI is a synchronous serial interface, which uses clock and
data pins for memory access and supports multiple devices on
the data bus. A device on the SPI bus is activated using the CS
pin.
The relationship between chip select, clock, and data is dictated
by the SPI mode. This device supports SPI modes 0 and 3. In
both of these modes, data is clocked into the F-RAM on the rising
edge of SCK starting from the first rising edge after CS goes
active.
The SPI protocol is controlled by opcodes. These opcodes
specify the commands from the bus master to the slave device.
After CS is activated, the first byte transferred from the bus
Document Number: 001-84500 Rev. *G
master is the opcode. Following the opcode, any addresses and
data are then transferred. The CS must go inactive after an
operation is complete and before a new opcode can be issued.
The commonly used terms in the SPI protocol are as follows:
SPI Master
The SPI master device controls the operations on a SPI bus. An
SPI bus may have only one master with one or more slave
devices. All the slaves share the same SPI bus lines and the
master may select any of the slave devices using the CS pin. All
of the operations must be initiated by the master activating a
slave device by pulling the CS pin of the slave LOW. The master
also generates the SCK and all the data transmission on SI and
SO lines are synchronized with this clock.
SPI Slave
The SPI slave device is activated by the master through the Chip
Select line. A slave device gets the SCK as an input from the SPI
master and all the communication is synchronized with this
clock. An SPI slave never initiates a communication on the SPI
bus and acts only on the instruction from the master.
The FM25V20 operates as an SPI slave and may share the SPI
bus with other SPI slave devices.
Chip Select (CS)
To select any slave device, the master needs to pull down the
corresponding CS pin. Any instruction can be issued to a slave
device only while the CS pin is LOW. When the device is not
selected, data through the SI pin is ignored and the serial output
pin (SO) remains in a high-impedance state.
Note A new instruction must begin with the falling edge of CS.
Therefore, only one opcode can be issued for each active Chip
Select cycle.
Serial Clock (SCK)
The Serial Clock is generated by the SPI master and the
communication is synchronized with this clock after CS goes
LOW.
The FM25V20 enables SPI modes 0 and 3 for data
communication. In both of these modes, the inputs are latched
by the slave device on the rising edge of SCK and outputs are
issued on the falling edge. Therefore, the first rising edge of SCK
signifies the arrival of the first bit (MSB) of a SPI instruction on
the SI pin. Further, all data inputs and outputs are synchronized
with SCK.
Data Transmission (SI/SO)
The SPI data bus consists of two lines, SI and SO, for serial data
communication. SI is also referred to as Master Out Slave In
(MOSI) and SO is referred to as Master In Slave Out (MISO). The
master issues instructions to the slave through the SI pin, while
the slave responds through the SO pin. Multiple slave devices
may share the SI and SO lines as described earlier.
The FM25V20 has two separate pins for SI and SO, which can
be connected with the master as shown in Figure 3.
Page 4 of 24
FM25V20
For a microcontroller that has no dedicated SPI bus, a
general-purpose port may be used. To reduce hardware
resources on the controller, it is possible to connect the two data
pins (SI, SO) together and tie off (HIGH) the HOLD and WP pins.
Figure 4 shows such a configuration, which uses only three pins.
Serial Opcode
After the slave device is selected with CS going LOW, the first
byte received is treated as the opcode for the intended operation.
FM25V20 uses the standard opcodes for memory accesses.
Invalid Opcode
Most Significant Bit (MSB)
The SPI protocol requires that the first bit to be transmitted is the
Most Significant Bit (MSB). This is valid for both address and
data transmission.
If an invalid opcode is received, the opcode is ignored and the
device ignores any additional serial data on the SI pin until the
next falling edge of CS, and the SO pin remains tristated.
Status Register
The 2-Mbit serial F-RAM requires a 3-byte address for any read
FM25V20 has an 8-bit Status Register. The bits in the Status
or write operation. Because the address is only 18 bits, the first
Register are used to configure the device. These bits are
six bits, which are fed in are ignored by the device. Although
described in Table 3 on page 7.
these six bits are ‘don’t care’, Cypress recommends that these
bits be set to 0s to enable seamless transition to higher memory
densities.
Figure 3. System Configuration with SPI Port
SCK
MOSI
MISO
SCK
SPI
Microcontroller
SI
SO
FM25V20
CS HOLD WP
SCK
SI
SO
FM25V20
CS HOLD WP
CS1
HO LD 1
WP1
CS2
HO LD 2
WP2
Figure 4. System Configuration without SPI Port
P1.0
P1.1
SCK
SI
SO
Microcontroller
FM25V20
CS HOLD WP
P1.2
SPI Modes
FM25V20 may be driven by a microcontroller with its SPI
peripheral running in either of the following two modes:
■
SPI Mode 0 (CPOL = 0, CPHA = 0)
■
SPI Mode 3 (CPOL = 1, CPHA = 1)
Document Number: 001-84500 Rev. *G
For both these modes, the input data is latched in on the rising
edge of SCK starting from the first rising edge after CS goes
active. If the clock starts from a HIGH state (in mode 3), the first
rising edge after the clock toggles is considered. The output data
is available on the falling edge of SCK.
Page 5 of 24
FM25V20
The two SPI modes are shown in Figure 5 on page 6 and Figure
6 on page 6. The status of the clock when the bus master is not
transferring data is:
■
SCK remains at 0 for Mode 0
■
SCK remains at 1 for Mode 3
The device detects the SPI mode from the status of the SCK pin
when the device is selected by bringing the CS pin LOW. If the
SCK pin is LOW when the device is selected, SPI Mode 0 is
assumed and if the SCK pin is HIGH, it works in SPI Mode 3.
Figure 5. SPI Mode 0
CS
0
1
2
3
5
4
6
7
SCK
WREN - Set Write Enable Latch
The FM25V20 will power up with writes disabled. The WREN
command must be issued before any write operation. Sending
the WREN opcode allows the user to issue subsequent opcodes
for write operations. These include writing the Status Register
(WRSR) and writing the memory (WRITE).
Sending the WREN opcode causes the internal Write Enable
Latch to be set. A flag bit in the Status Register, called WEL,
indicates the state of the latch. WEL = ’1’ indicates that writes are
permitted. Attempting to write the WEL bit in the Status Register
has no effect on the state of this bit – only the WREN opcode can
set this bit. The WEL bit will be automatically cleared on the rising
edge of CS following a WRDI, a WRSR, or a WRITE operation.
This prevents further writes to the Status Register or the F-RAM
array without another WREN command. Figure 7 illustrates the
WREN command bus configuration.
Figure 7. WREN Bus Configuration
SI
7
6
5
4
3
2
1
0
MSB
CS
LSB
0
SI
CS
1
2
3
5
4
6
7
3
4
5
6
7
0
0
0
0
1
1
0
HI-Z
WRDI - Reset Write Enable Latch
7
6
5
4
3
2
MSB
1
0
LSB
Power Up to First Access
The FM25V20 is not accessible for a tPU time after power-up.
Users must comply with the timing parameter, tPU, which is the
minimum time from VDD (min) to the first CS LOW.
Command Structure
There are nine commands, called opcodes, that can be issued
by the bus master to the FM25V20. They are listed in Table 1.
These opcodes control the functions performed by the memory.
Table 1. Opcode Commands
Name
0
SO
SCK
SI
2
SCK
Figure 6. SPI Mode 3
0
1
Description
Opcode
WREN
Set write enable latch
0000 0110b
WRDI
Reset write enable latch
0000 0100b
RDSR
Read Status Register
0000 0101b
WRSR
Write Status Register
0000 0001b
READ
Read memory data
0000 0011b
FSTRD
Fast read memory data
0000 1011b
WRITE
Write memory data
0000 0010b
SLEEP
Enter sleep mode
1011 1001b
RDID
Read device ID
1001 1111b
Document Number: 001-84500 Rev. *G
The WRDI command disables all write activity by clearing the
Write Enable Latch. The user can verify that writes are disabled
by reading the WEL bit in the Status Register and verifying that
WEL is equal to ‘0’. Figure 8 illustrates the WRDI command bus
configuration.
Figure 8. WRDI Bus Configuration
CS
0
1
2
3
4
5
6
7
SCK
SI
SO
0
0
0
0
0
1
0
0
HI-Z
Page 6 of 24
FM25V20
Status Register and Write Protection
The write protection features of the FM25V20 are multi-tiered
and are enabled through the status register. The Status Register
is organized as follows. (The default value shipped from the
factory for bit 0, WEL, BP0, BP1, bits 4–5, WPEN is ‘0’, and for
bit 6 is ‘1’.)
Table 2. Status Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
WPEN (0)
X (1)
X (0)
X (0)
BP1 (0)
BP0 (0)
WEL (0)
X (0)
Table 3. Status Register Bit Definition
Bit
Definition
Description
Bit 0
Don’t care
This bit is non-writable and always returns ‘0’ upon read.
Bit 1 (WEL)
Write Enable
WEL indicates if the device is write enabled. This bit defaults to ‘0’ (disabled) on power-up.
WEL = '1' --> Write enabled
WEL = '0' --> Write disabled
Bit 2 (BP0)
Block Protect bit ‘0’
Used for block protection. For details, see Table 4 on page 7.
Bit 3 (BP1)
Block Protect bit ‘1’
Used for block protection. For details, see Table 4 on page 7.
Bit 4-5
Don’t care
These bits are non-writable and always return ‘0’ upon read.
Bit 6
Don’t care
This bit is non-writable and always returns ‘1’ upon read.
Bit 7 (WPEN)
Write Protect Enable bit Used to enable the function of Write Protect Pin (WP). For details, see Table 5 on page 7.
Bits 0 and 4-5 are fixed at ‘0’ and bit 6 is fixed at ‘1’; none of these
bits can be modified. Note that bit 0 ("Ready or Write in progress”
bit in serial flash and EEPROM) is unnecessary, as the F-RAM
writes in real-time and is never busy, so it reads out as a ‘0’. An
exception to this is when the device is waking up from sleep
mode, which is described in Sleep Mode on page 11. The BP1
and BP0 control the software write-protection features and are
nonvolatile bits. The WEL flag indicates the state of the Write
Enable Latch. Attempting to directly write the WEL bit in the
Status Register has no effect on its state. This bit is internally set
and cleared via the WREN and WRDI commands, respectively.
BP1 and BP0 are memory block write protection bits. They
specify portions of memory that are write-protected as shown in
Table 4.
The BP1 and BP0 bits and the Write Enable Latch are the only
mechanisms that protect the memory from writes. The remaining
write protection features protect inadvertent changes to the block
protect bits.
The write protect enable bit (WPEN) in the Status Register
controls the effect of the hardware write protect (WP) pin. When
the WPEN bit is set to '0', the status of the WP pin is ignored.
When the WPEN bit is set to '1', a LOW on the WP pin inhibits a
write to the Status Register. Thus the Status Register is
write-protected only when WPEN = '1' and WP = '0'.
Table 5 summarizes the write protection conditions.
Table 5. Write Protection
WEL WPEN WP
Table 4. Block Memory Write Protection
BP1
BP0
Protected Address Range
0
0
None
0
1
30000h to 3FFFFh (upper 1/4)
1
0
20000h to 3FFFFh (upper 1/2)
1
1
00000h to 3FFFFh (all)
Document Number: 001-84500 Rev. *G
0
Protected Unprotected
Blocks
Blocks
Status
Register
Protected
Protected
Protected
X
X
1
0
X
Protected
Unprotected
Unprotected
1
1
0
Protected
Unprotected
Protected
1
1
1
Protected
Unprotected
Unprotected
Page 7 of 24
FM25V20
RDSR - Read Status Register
WRSR - Write Status Register
The RDSR command allows the bus master to verify the
contents of the Status Register. Reading the status register
provides information about the current state of the
write-protection features. Following the RDSR opcode, the
FM25V20 will return one byte with the contents of the Status
Register.
The WRSR command allows the SPI bus master to write into the
Status Register and change the write protect configuration by
setting the WPEN, BP0 and BP1 bits as required. Before issuing
a WRSR command, the WP pin must be HIGH or inactive. Note
that on the FM25V20, WP only prevents writing to the Status
Register, not the memory array. Before sending the WRSR
command, the user must send a WREN command to enable
writes. Executing a WRSR command is a write operation and
therefore, clears the Write Enable Latch.
Figure 9. RDSR Bus Configuration
CS
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
SCK
Opcode
0
SI
0
0
0
0
1
0
1
0
Data
HI-Z
SO
D7 D6 D5 D4 D3 D2 D1 D0
MSB
LSB
Figure 10. WRSR Bus Configuration (WREN not shown)
CS
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
SCK
Data
Opcode
SI
0
SO
0
0
0
0
0
0
1 D7 X
MSB
X D3 D2 X
X
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 FM25V20 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 with CS
being asserted and deasserted. The next opcode is WRITE. The
WRITE opcode is followed by a three-byte address containing
the 18-bit address (A17-A0) of the first data byte to be written into
the memory. The upper six bits of the three-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
Document Number: 001-84500 Rev. *G
X
the last address of 3FFFFh is reached, the counter will roll over
to 00000h. Data is written MSB first. The rising edge of CS
terminates a write operation. A write operation is shown in
Figure 11.
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.
Page 8 of 24
FM25V20
Read Operation
FAST READ opcode is followed by a three-byte address
containing the 18-bit address (A17-A0) of the first byte of the
read operation and then a dummy byte. The dummy byte inserts
a read latency of 8-clock cycle. The fast read operation is
otherwise the same as an ordinary read operation except that it
requires an additional dummy byte. After receiving opcode,
address, and a dummy byte, the FM25V20 starts driving its SO
line with data bytes, with MSB first, and continues transmitting
as long as the device is selected and the clock is available. In
case of bulk read, the internal address counter is incremented
automatically, and after the last address 3FFFFh is reached, the
counter rolls over to 00000h. When the device is driving data on
its SO line, any transition on its SI line is ignored. The rising edge
of CS terminates a fast read operation and tristates the SO pin.
A Fast Read operation is shown in Figure 13.
After the falling edge of CS, the bus master can issue a READ
opcode. Following the READ command is a three-byte address
containing the 18-bit address (A17-A0) of the first byte of the
read operation. The upper six 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 3FFFFh is reached, the counter will
roll over to 00000h. 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 12.
Fast Read Operation
The FM25V20 supports a FAST READ opcode (0Bh) that is
provided for code compatibility with serial flash devices. The
Figure 11. Memory Write (WREN not shown) Operation
CS
1
2
3
4
5
6
7
0
1
2
3
4
5
6
Opcode
SI
0
0
0
0
0
7
~
~ ~
~
0
SCK
20 21 22 23 0
1
1
0
X
X
X
X
X
X A17 A16
MSB
3
4
5
6
7
Data
18-bit Address
0
2
A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
LSB MSB
LSB
HI-Z
SO
Figure 12. Memory Read Operation
CS
1
2
3
4
5
6
7
0
1
2
3
4
Opcode
SI
0
0
0
0
0
5
6
7
~
~ ~
~
0
SCK
20 21 22 23 0
1
2
3
4
5
6
7
18-bit Address
0
1
1
X
X
X
MSB
SO
X
X
X A17 A16
A3 A2 A1 A0
LSB
Data
HI-Z
D7 D6 D5 D4 D3 D2 D1 D0
MSB
Document Number: 001-84500 Rev. *G
LSB
Page 9 of 24
FM25V20
Figure 13. Fast Read Operation
CS
1
2
3
4
5 6
7
0
1
2
3
4
5
SCK
Opcode
SI
0
0
0
0
1
6
7
~
~ ~
~
0
20 21 22 23 24 25 26 27 28 29 30 31 0
18-bit Address
0
1 1
X X
X
X
X X A17 A16
MSB
2
X
X X
X
The HOLD pin can be used to interrupt a serial operation without
aborting it. If the bus master pulls the HOLD pin LOW while SCK
is LOW, the current operation will pause. Taking the HOLD pin
5
6
7
X X X
LSB
Data
D7 D6 D5 D4 D3 D2 D1 D0
MSB
HOLD Pin Operation
3 4
Dummy Byte
A3 A2 A1 A0 X
HI-Z
SO
1
LSB
HIGH while SCK is LOW will resume an operation. The
transitions of HOLD must occur while SCK is LOW, but the SCK
and CS pin can toggle during a hold state.
~
~
Figure 14. HOLD Operation[2]
~
~
CS
SI
VALID IN
SO
VALID IN
~
~
HOLD
~
~
~
~
SCK
Note
2. Figure shows HOLD operation for input mode and output mode.
Document Number: 001-84500 Rev. *G
Page 10 of 24
FM25V20
Sleep Mode
pin. On the next falling edge of CS, the device will return to
normal operation within tREC time. The SO pin remains in a HI-Z
state during the wakeup period. The device does not necessarily
respond to an opcode within the wakeup period. To start the
wakeup procedure, the controller may send a “dummy” read, for
example, and wait the remaining tREC time.
A low-power sleep mode is implemented on the FM25V20
device. The device will enter the low-power state when the
SLEEP opcode B9h is clocked in and a rising edge of CS is
applied. When in sleep mode, the SCK and SI pins are ignored
and SO will be HI-Z, but the device continues to monitor the CS
Figure 15. Sleep Mode Operation
Enters Sleep Mode
t REC Recovers from Sleep Mode
CS
0
1
2
3
4
5
6
t SU
7
SCK
SI
1
0
1
1
1
0
0
VALID IN
1
HI-Z
SO
Device ID
The FM25V20 device can be interrogated for its manufacturer,
product identification, and die revision. The RDID opcode 9Fh
allows the user to read the manufacturer ID and product ID, both
of which are read-only bytes. The JEDEC-assigned
manufacturer ID places the Cypress (Ramtron) identifier in bank
7; therefore, there are six bytes of the continuation code 7Fh
followed by the single byte C2h. There are two bytes of product
ID, which includes a family code, a density code, a sub code, and
the product revision code.
Table 6. Device ID
Device ID Description
71–16
(56 bits)
Device ID
(9 bytes)
Manufacturer ID
7F7F7F7F7F7FC22500h
0111111101111111011111110111
1111011111110111111111000010
15–13
(3 bits)
12–8
(5 bits)
7–6
(2 bits)
5–3
(3 bits)
2–0
(3 bits)
Product ID
Family
Density
Sub
Rev
Rsvd
001
00101
00
000
000
Figure 16. Read Device ID
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
SCK
~
~
CS
44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
Opcode
SO
1
0
0 1
1
1
1
1
HI-Z
D7 D6 D5 D4 D3 D2 D1 D0
~
~
SI
D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
MSB
LSB
9-Byte Device ID
Document Number: 001-84500 Rev. *G
Page 11 of 24
FM25V20
Endurance
The FM25V20 devices are capable of being accessed at least
1014 times, reads or writes. An F-RAM memory operates with a
read and restore mechanism. Therefore, an endurance cycle is
applied on a row basis for each access (read or write) to the
memory array. The F-RAM architecture is based on an array of
rows and columns of 32K rows of 64-bits each. The entire row is
internally accessed once, whether a single byte or all eight bytes
are read or written. Each byte in the row is counted only once in
an endurance calculation. Table 7 shows endurance calculations
for a 64-byte repeating loop, which includes an opcode, a starting
address, and a sequential 64-byte data stream. This causes
each byte to experience one endurance cycle through the loop.
F-RAM read and write endurance is virtually unlimited even at a
40-MHz clock rate.
Document Number: 001-84500 Rev. *G
Table 7. Time to Reach Endurance Limit for Repeating
64-byte Loop
SCK Freq
(MHz)
Endurance
Cycles/sec
Endurance
Cycles/year
Years to Reach
Limit
40
73,520
2.32 × 1012
43.1
18,380
5.79 ×
1011
172.7
2.90 ×
1011
345.4
10
5
9,190
Page 12 of 24
FM25V20
Maximum Ratings
Surface mount lead soldering
temperature (3 seconds) ......................................... +260 C
Exceeding maximum ratings may shorten the useful life of the
device. These user guidelines are not tested.
DC output current (1 output at a time, 1s duration) .... 15 mA
Storage temperature ................................ –55 C to +125 C
Electrostatic Discharge Voltage
Human Body Model (JEDEC Std JESD22-A114-B) .............. 4 kV
Maximum junction temperature ................................... 95 C
Charged Device Model (JEDEC Std JESD22-C101-A) ..... 1.25 kV
Supply voltage on VDD relative to VSS .........–1.0 V to +4.5 V
Machine Model (JEDEC Std JESD22-A115-A) ...................... 250 V
Input voltage ........... –1.0 V to +4.5 V and VIN < VDD + 1.0 V
Latch-up current .................................................... > 140 mA
DC voltage applied to outputs
in High-Z state .................................... –0.5 V to VDD + 0.5 V
Operating Range
Transient voltage (< 20 ns) on
any pin to ground potential ................. –2.0 V to VDD + 2.0 V
Package power dissipation
capability (TA = 25 °C) ................................................. 1.0 W
Range
Ambient Temperature (TA)
VDD
–40 C to +85 C
2.0 V to 3.6 V
Industrial
DC Electrical Characteristics
Over the Operating Range
Parameter
Description
VDD
Power supply
IDD
VDD supply current
Test Conditions
SCK
toggling fSCK = 1 MHz;
between
f
= 40 MHz;
VDD – 0.2 V and VSS, SCK
other inputs
VSS or VDD – 0.2 V.
SO = Open
Min
Typ[3]
Max
Unit
2.0
3.3
3.6
V
–
0.13
0.30
mA
–
1.4
3
mA
ISB
VDD standby current
CS = VDD. All other inputs VSS or VDD.
–
100
250
A
IZZ
Sleep mode current
TA = 25 C
CS = VDD.
All other inputs VSS or
TA = 85 C
VDD.
–
3
5
A
–
–
8
A
ILI
Input leakage current
VSS < VIN < VDD
–
–
±1
A
ILO
Output leakage current
VSS < VOUT < VDD
–
–
±1
A
VIH
Input HIGH voltage
0.7 × VDD
–
VDD + 0.3
V
VIL
Input LOW voltage
– 0.3
–
0.3 × VDD
V
VOH1
Output HIGH voltage
IOH = –1 mA, VDD = 2.7 V.
2.4
–
–
V
VOH2
Output HIGH voltage
IOH = –100 A
VDD – 0.2
–
–
V
VOL1
Output LOW voltage
IOL = 2 mA, VDD = 2.7 V
–
–
0.4
V
VOL2
Output LOW voltage
IOL = 150 A
–
–
0.2
V
Note
3. Typical values are at 25 °C, VDD = VDD (typ). Not 100% tested.
Document Number: 001-84500 Rev. *G
Page 13 of 24
FM25V20
Data Retention and Endurance
Parameter
TDR
NVC
Description
Data retention
Endurance
Test condition
Min
Max
Unit
TA = 85 C
10
–
Years
TA = 75 C
38
–
TA = 65 C
151
–
14
–
Over operating temperature
10
Cycles
Capacitance
Parameter [4]
Description
CO
Output pin capacitance (SO)
CI
Input pin capacitance
Test Conditions
TA = 25 C, f = 1 MHz, VDD = VDD(typ)
Max
Unit
8
pF
6
pF
Thermal Resistance
Parameter
JA
JC
Description
Thermal resistance
(junction to ambient)
Thermal resistance
(junction to case)
Test Conditions
8-pin SOIC
8-pin TDFN
Unit
Test conditions follow standard test
methods and procedures for measuring
thermal impedance, per EIA / JESD51.
114
17
C/W
40
11
C/W
AC Test Conditions
Input pulse levels .................................10% and 90% of VDD
Input rise and fall times ...................................................3 ns
Input and output timing reference levels ................0.5 × VDD
Output load capacitance .............................................. 30 pF
Note
4. This parameter is characterized and not 100% tested.
Document Number: 001-84500 Rev. *G
Page 14 of 24
FM25V20
AC Switching Characteristics
Over the Operating Range
Parameters [5]
Cypress
Parameter
VDD = 2.0 V to 2.7 V
Description
Alt.
Parameter
VDD = 2.7 V to 3.6 V
Min
Max
Min
Max
Unit
fSCK
–
SCK clock frequency
0
25
0
40
MHz
tCH
–
Clock HIGH time
18
–
11
–
ns
tCL
–
Clock LOW time
18
–
11
–
ns
tCSU
tCSS
Chip select setup
12
–
10
–
ns
tCSH
tCSH
Chip select hold
12
–
10
–
ns
tHZCS
Output disable time
–
20
–
12
ns
tODV
tCO
Output data valid time
–
16
–
9
ns
tOH
–
Output hold time
0
–
0
–
ns
tD
tOD
[6, 7]
–
Deselect time
60
–
40
–
ns
[8, 9]
–
Data in rise time
–
50
–
50
ns
tF[8, 9]
–
Data in fall time
–
50
–
50
ns
tSU
tSD
Data setup time
8
–
5
–
ns
tH
tHD
Data hold time
8
–
5
–
ns
tHS
tSH
HOLD setup time
12
–
10
–
ns
tHH
tHH
HOLD hold time
12
–
10
–
ns
tHZ[6, 7]
tLZ[7]
tHHZ
HOLD LOW to HI-Z
–
25
–
20
ns
tHLZ
HOLD HIGH to data active
–
25
–
20
ns
tR
Notes
5. Test conditions assume a signal transition time of 3 ns or less, timing reference levels of 0.5 × VDD, input pulse levels of 10% to 90% of VDD, and output loading of
the specified IOL/IOH and 30 pF load capacitance shown in AC Test Conditions on page 14.
6. tOD and tHZ are specified with a load capacitance of 5 pF. Transition is measured when the outputs enter a high impedance state
7. This parameter is characterized and not 100% tested.
8. Rise and fall times measured between 10% and 90% of waveform.
9. These parameters are guaranteed by design and are not tested.
Document Number: 001-84500 Rev. *G
Page 15 of 24
FM25V20
Figure 17. Synchronous Data Timing (Mode 0)
tD
CS
tCSU
tCH
tCL
tCSH
SCK
tSU
SI
tH
VALID IN
VALID IN
VALID IN
tOH
tODV
SO
HI-Z
tOD
HI-Z
CS
SCK
tHH
~
~
~
~
Figure 18. HOLD Timing
tHS
~
~
tHS
VALID IN
tHZ
Document Number: 001-84500 Rev. *G
VALID IN
tLZ
~
~
SO
tSU
~
~
HOLD
SI
tHH
Page 16 of 24
FM25V20
Power Cycle Timing
Over the Operating Range
Parameter
Description
Min
Max
Unit
tPU
Power-up VDD(min) to first access (CS LOW)
1
–
ms
tPD
Last access (CS HIGH) to power-down (VDD(min))
0
–
µs
tVR [10]
VDD power-up ramp rate
50
–
µs/V
tVF [10]
VDD power-down ramp rate
100
–
µs/V
tREC [11]
Recovery time from sleep mode
–
450
µs
VDD
~
~
Figure 19. Power Cycle Timing
VDD(min)
tVR
CS
tVF
tPD
~
~
tPU
VDD(min)
Notes
10. Slope measured at any point on the VDD waveform.
11. Guaranteed by design. Refer to Figure 15 for sleep mode recovery timing.
Document Number: 001-84500 Rev. *G
Page 17 of 24
FM25V20
Ordering Information
Package
Diagram
Ordering Code
Package Type
FM25V20-G
001-85261
8-pin SOIC
FM25V20-GTR
001-85261
8-pin SOIC
FM25V20-DG
001-85579
8-pin TDFN
FM25V20-DGTR
001-85579
8-pin TDFN
Operating
Range
Industrial
All these parts are Pb-free. Contact your local Cypress sales representative for availability of these parts.
Ordering Code Definitions
FM 25
V
20 -
G
TR
Option:
blank = Standard; TR = Tape and Reel
Package Type:
G = 8-pin SOIC; DG = 8-pin TDFN
Density: 20 = 2-Mbit
Voltage: V = 2.0 V to 3.6 V
SPI F-RAM
Cypress
Document Number: 001-84500 Rev. *G
Page 18 of 24
FM25V20
Package Diagrams
Figure 20. 8-pin SOIC (208 Mils) Package Outline, 001-85261
001-85261 **
Document Number: 001-84500 Rev. *G
Page 19 of 24
FM25V20
Package Diagrams (continued)
Figure 21. 8-pin DFN (5 mm × 6 mm × 0.75 mm) Package Outline, 001-85579
001-85579 *A
Document Number: 001-84500 Rev. *G
Page 20 of 24
FM25V20
Acronyms
Acronym
Document Conventions
Description
Units of Measure
CPHA
Clock Phase
CPOL
Clock Polarity
°C
degree Celsius
EEPROM
Electrically Erasable Programmable Read-Only
Memory
Hz
hertz
kHz
kilohertz
EIA
Electronic Industries Alliance
k
kilohm
F-RAM
Ferroelectric Random Access Memory
Mbit
megabit
I/O
Input/Output
MHz
megahertz
JEDEC
Joint Electron Devices Engineering Council
A
microampere
JESD
JEDEC Standards
F
microfarad
LSB
Least Significant Bit
s
microsecond
mA
milliampere
ms
millisecond
ns
nanosecond
ohm
%
percent
pF
picofarad
V
volt
W
watt
MSB
Most Significant Bit
RoHS
Restriction of Hazardous Substances
SPI
Serial Peripheral Interface
SOIC
Small Outline Integrated Circuit
TDFN
Thin Dual Flat No-lead
Document Number: 001-84500 Rev. *G
Symbol
Unit of Measure
Page 21 of 24
FM25V20
Document History Page
Document Title: FM25V20, 2-Mbit (256 K × 8) Serial (SPI) F-RAM
Document Number: 001-84500
Rev.
ECN No.
Orig. of
Change
Submission
Date
**
3869802
GVCH
01/15/13
*A
3938799
GVCH
05/08/13
*B
4123023
GVCH
09/20/2013
Description of Change
New spec.
Removed PDIP package.
Converted source from word file to frame maker file.
Updated AC Switching Characteristics:
Changed minimum value of tCH parameter from 20 ns to 18 ns for “VDD = 2.0 V
to 2.7 V”.
Changed minimum value of tCL parameter from 20 ns to 18 ns for “VDD = 2.0 V
to 2.7 V”.
Changed maximum value of tODV parameter from 18 ns to 16 ns for
“VDD = 2.0 V to 2.7 V”.
*C
4136685
GVCH
10/01/2013
Updated Pin Definitions:
Updated description of WP and HOLD pins (Added additional information “This
pin must be tied to VDD if not used”.
Updated description of VDD and VSS pins for clarity.
Updated Memory Operation:
Updated Sleep Mode:
Updated Figure 15 (Added tREC timing).
Updated Power Cycle Timing:
Changed description of tVR parameter from “VDD rise time” to “VDD power-up
slew rate”.
Changed description of tVF parameter from “VDD fall time” to “VDD power-down
slew rate”.
Document Number: 001-84500 Rev. *G
Page 22 of 24
FM25V20
Document History Page (continued)
Document Title: FM25V20, 2-Mbit (256 K × 8) Serial (SPI) F-RAM
Document Number: 001-84500
Rev.
ECN No.
Orig. of
Change
Submission
Date
*D
4223057
GVCH
01/23/2014
Description of Change
Changed status from Preliminary to Final.
Updated Figure 2
Updated Device ID:
Updated Table 6:
Changed Device ID (9
7F7F7F7F7F7FC22500h.
bytes)
from
7F7F7F7F7F7FC20025h
to
Updated DC Electrical Characteristics:
Updated Test Conditions of ILI parameter (Removed VSS < VOUT < VDD).
Updated Test Conditions of ILO parameter (Removed VSS < VIN < VDD).
Updated Data Retention and Endurance:
Changed minimum value of TDR parameter from 37 years to 38 years at Test
Condition “75 C”.
Changed minimum value of TDR parameter from 145 years to 151 years at Test
Condition “85 C”.
Updated Power Cycle Timing:
Changed description of tVR parameter from “VDD power-up slew rate” to “VDD
power-up ramp rate”.
Changed description of tVF parameter from “VDD power-down slew rate” to
“VDD power-down ramp rate”.
Updated Package Diagrams:
Updated Figure 21.
Completing Sunset Review.
*E
4462384
GVCH
07/31/2014
Updated Package Diagrams:
spec 001-85579 – Changed revision from ** to *A.
*F
4563141
GVCH
11/06/2014
Added related documentation hyperlink in page 1.
*G
4784456
GVCH
06/02/2015
Obsolete document.
Document Number: 001-84500 Rev. *G
Page 23 of 24
FM25V20
Sales, Solutions, and Legal Information
Worldwide Sales and Design Support
Cypress maintains a worldwide network of offices, solution centers, manufacturer’s representatives, and distributors. To find the office
closest to you, visit us at Cypress Locations.
PSoC® Solutions
Products
Automotive
Clocks & Buffers
Interface
Lighting & Power Control
cypress.com/go/automotive
cypress.com/go/clocks
cypress.com/go/interface
cypress.com/go/powerpsoc
cypress.com/go/plc
Memory
PSoC
Touch Sensing
USB Controllers
Wireless/RF
cypress.com/go/memory
cypress.com/go/psoc
psoc.cypress.com/solutions
PSoC 1 | PSoC 3 | PSoC 4 | PSoC 5LP
Cypress Developer Community
Community | Forums | Blogs | Video | Training
Technical Support
cypress.com/go/support
cypress.com/go/touch
cypress.com/go/USB
cypress.com/go/wireless
© Cypress Semiconductor Corporation, 2013-2015. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of
any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used for
medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as
critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support systems
application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Any Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide patent protection (United States and foreign),
United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a personal, non-exclusive, non-transferable license to copy, use, modify, create derivative works of,
and compile the Cypress Source Code and derivative works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in conjunction with a Cypress
integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source Code except as specified above is prohibited without
the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials described herein. Cypress does not
assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in life-support systems where
a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application implies that the manufacturer
assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
Document Number: 001-84500 Rev. *G
Revised June 2, 2015
All products and company names mentioned in this document may be the trademarks of their respective holders.
Page 24 of 24
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