FM25640B
64-Kbit (8 K × 8) Serial (SPI) Automotive
F-RAM
64-Kbit (8 K × 8) Serial (SPI) Automotive F-RAM
Features
Functional Description
■
64-Kbit ferroelectric random access memory (F-RAM) logically
organized as 8 K × 8
13
❐ High-endurance 10 trillion (10 ) read/writes
❐ 121-year data retention (See the Data Retention and
Endurance table)
❐ NoDelay™ writes
❐ Advanced high-reliability ferroelectric process
The FM25640B is a 64-Kbit 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 121 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 4 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
Unlike serial flash and EEPROM, the FM25640B 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 FM25640B is capable of supporting
1013 read/write cycles, or 10 million times more write cycles than
EEPROM.
■
Low power consumption
❐ 300 A active current at 1 MHz
❐ 10 A (typ) standby current at +85 C
■
Voltage operation: VDD = 4.5 V to 5.5 V
■
Automotive-E temperature: –40 C to +125 C
■
8-pin small outline integrated circuit (SOIC) package
■
AEC Q100 Grade 1 compliant
■
Restriction of hazardous substances (RoHS) compliant
These capabilities make the FM25640B 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 FM25640B provides substantial benefits to users of serial
EEPROM or flash as a hardware drop-in replacement. The
FM25640B uses the high-speed SPI bus, which enhances the
high-speed write capability of F-RAM technology. The device
specifications are guaranteed over an automotive-e temperature
range of –40 C to +125 C.
For a complete list of related resources, click here.
Logic Block Diagram
WP
Instruction Decoder
Clock Generator
Control Logic
Write Protect
CS
HOLD
SCK
8Kx8
F-RAM Array
Instruction Register
Address Register
Counter
13
8
SI
Data I/O Register
SO
3
Nonvolatile Status
Register
Cypress Semiconductor Corporation
Document Number: 001-86148 Rev. *C
•
198 Champion Court
•
San Jose, CA 95134-1709
•
408-943-2600
Revised August 14, 2015
FM25640B
Contents
Pinout ................................................................................ 3
Pin Definitions .................................................................. 3
Functional 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 ............................. 6
RDSR - Read Status Register ..................................... 7
WRSR - Write Status Register .................................... 7
Memory Operation ............................................................ 8
Write Operation ........................................................... 8
Read Operation ........................................................... 8
HOLD Pin Operation ................................................... 9
Endurance ................................................................. 10
Maximum Ratings ........................................................... 11
Operating Range ............................................................. 11
DC Electrical Characteristics ........................................ 11
Document Number: 001-86148 Rev. *C
Data Retention and Endurance ..................................... 12
Example of an F-RAM Life Time
in an AEC-Q100 Automotive Application ..................... 12
Capacitance .................................................................... 12
Thermal Resistance ........................................................ 12
AC Test Conditions ........................................................ 12
AC Switching Characteristics ....................................... 13
Power Cycle Timing ....................................................... 15
Ordering Information ...................................................... 16
Ordering Code Definitions ......................................... 16
Package Diagram ............................................................ 17
Acronyms ........................................................................ 18
Document Conventions ................................................. 18
Units of Measure ....................................................... 18
Document History Page ................................................. 19
Sales, Solutions, and Legal Information ...................... 20
Worldwide Sales and Design Support ....................... 20
Products .................................................................... 20
PSoC® Solutions ...................................................... 20
Cypress Developer Community ................................. 20
Technical Support ..................................................... 20
Page 2 of 20
FM25640B
Pinout
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
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 tristates the output. 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 4 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. Note that the function of WP is different from the
FM25040 where it prevents all writes to the part.
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 input to the device.
Note
1. SI may be connected to SO for a single pin data interface.
Document Number: 001-86148 Rev. *C
Page 3 of 20
FM25640B
Functional Overview
edge of SCK starting from the first rising edge after CS goes
active.
The FM25640B is a serial F-RAM memory. The memory array is
logically organized as 8,192 × 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 FM25640B
and a serial flash or EEPROM with the same pinout is the
F-RAM's superior write performance, high endurance, and low
power consumption.
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
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:
Memory Architecture
When accessing the FM25640B, the user addresses 8K
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 two-byte address. The upper 3 bits
of the address range are 'don't care' values. The complete
address of 13 bits specifies each byte address uniquely.
Most functions of the FM25640B 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.
Note The FM25640B contains no power management circuits
other than a simple internal power-on reset circuit. It is the user’s
responsibility to ensure that VDD is within datasheet tolerances
to prevent incorrect operation. It is recommended that the part is
not powered down with chip enable active.
Serial Peripheral Interface – SPI Bus
The FM25640B is a SPI slave device and operates at speeds up
to 4 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 FM25640B 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
Document Number: 001-86148 Rev. *C
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 FM25640B 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 FM25640B 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
Page 4 of 20
FM25640B
these three bits are ‘don’t care’, Cypress recommends that these
bits be set to 0s to enable seamless transition to higher memory
densities.
the slave responds through the SO pin. Multiple slave devices
may share the SI and SO lines as described earlier.
The FM25640B has two separate pins for SI and SO, which can
be connected with the master as shown in Figure 2.
Serial Opcode
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 3 shows such a configuration, which uses only three pins.
After the slave device is selected with CS going LOW, the first
byte received is treated as the opcode for the intended operation.
FM25640B uses the standard opcodes for memory accesses.
Invalid Opcode
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.
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.
Status Register
The 64-Kbit serial F-RAM requires a 2-byte address for any read
or write operation. Because the address is only 13 bits, the first
three bits which are fed in are ignored by the device. Although
FM25640B has an 8-bit Status Register. The bits in the Status
Register are used to configure the device. These bits are
described in Table 3 on page 7.
Figure 2. System Configuration with SPI port
SCK
MOSI
MISO
SCK
SPI
Microcontroller
SI
SO
FM25640B
CS HOLD WP
SCK
SI
SO
FM25640B
CS HOLD WP
CS1
HO LD 1
WP1
CS2
HO LD 2
WP2
Figure 3. System Configuration without SPI port
P1.0
P1.1
SCK
SI
SO
Microcontroller
FM25640B
CS HOLD WP
P1.2
■
SPI Modes
FM25640B 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)
Document Number: 001-86148 Rev. *C
SPI Mode 3 (CPOL = 1, CPHA = 1)
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 20
FM25640B
The two SPI modes are shown in Figure 4 on page 6 and Figure
5 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 4. SPI Mode 0
CS
0
1
2
3
5
4
6
7
WREN - Set Write Enable Latch
The FM25640B 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 6 illustrates the
WREN command bus configuration.
SCK
Figure 6. WREN Bus Configuration
SI
7
6
5
4
3
2
1
0
MSB
CS
0
LSB
1
2
3
4
5
6
7
SCK
Figure 5. SPI Mode 3
SI
0
0
0
0
CS
0
1
2
3
5
4
6
1
0
WRDI - Reset Write Enable Latch
SCK
SI
1
HI-Z
SO
7
0
7
6
5
4
3
2
MSB
1
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 7 illustrates the WRDI command bus
configuration.
0
LSB
Power Up to First Access
The FM25640B 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.
There are six commands, called opcodes, that can be issued by
the bus master to the FM25640B. They are listed in Table 1.
These opcodes control the functions performed by the memory.
Table 1. Opcode commands
Description
1
2
3
4
5
6
7
SCK
SI
SO
0
0
0
0
0
1
0
0
HI-Z
Opcode
WREN
Set write enable latch
0000 0110b
WRDI
Write disable
0000 0100b
RDSR
Read Status Register
0000 0101b
WRSR
Write Status Register
0000 0001b
READ
Read memory data
0000 0011b
WRITE
Write memory data
0000 0010b
Document Number: 001-86148 Rev. *C
CS
0
Command Structure
Name
Figure 7. WRDI Bus Configuration
Page 6 of 20
FM25640B
Status Register and Write Protection
The write protection features of the FM25640B 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 bits in the Status Register is ‘0’.)
Table 2. Status Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
WPEN (0)
X (0)
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 Latch
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 4-6
Don’t care
These bits are non-writable and always return ‘0’ 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 4-6 are fixed at ‘0’; 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’. 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.
Table 4. Block Memory Write Protection
BP1
BP0
Protected Address Range
0
0
None
0
1
1800h to 1FFFh (upper 1/4)
1
0
1000h to 1FFFh (upper 1/2)
1
1
0000h to 1FFFh (all)
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
Document Number: 001-86148 Rev. *C
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
Protected Unprotected
Blocks
Blocks
Status
Register
Protected
Protected
Protected
0
X
X
1
0
X
Protected
Unprotected
Unprotected
1
1
0
Protected
Unprotected
Protected
1
1
1
Protected
Unprotected
Unprotected
RDSR - Read 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
FM25640B will return one byte with the contents of the Status
Register.
WRSR - Write 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 FM25640B, 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.
Page 7 of 20
FM25640B
Figure 8. RDSR Bus Configuration
CS
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
SCK
Opcode
SI
0
0
0
0
0
1
0
1
0
Data
HI-Z
SO
D7 D6 D5 D4 D3 D2 D1 D0
MSB
LSB
Figure 9. 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 FM25640B 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 13-bit
address (A12-A0) of the first data byte to be written into the
memory. The upper three 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 1FFFh is reached, the counter will roll over to
0000h. 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.
Document Number: 001-86148 Rev. *C
X
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 13-bit address (A12-A0) of the first byte of the
read operation. The upper three 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 1FFFh is reached, the counter will roll
over to 0000h. 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.
Page 8 of 20
FM25640B
Figure 10. Memory Write (WREN not shown)
CS
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Opcode
SI
0
0
0
0
0
~
~ ~
~
0
SCK
12 13 14 15 0
1
1
0
X
X
X A12 A11 A10 A9 A8
MSB
3
4
5
6
7
Data
13-bit Address
0
2
A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
LSB MSB
LSB
HI-Z
SO
Figure 11. Memory Read
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
12 13 14 15 0
1
2
3
4
5
6
7
13-bit Address
0
1
1
X
X
X A12 A11 A10 A9 A8
MSB
A3 A2 A1 A0
LSB
Data
HI-Z
SO
D7 D6 D5 D4 D3 D2 D1 D0
MSB
HOLD Pin Operation
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
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 12. 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: 001-86148 Rev. *C
Page 9 of 20
FM25640B
Endurance
The FM25640B devices are capable of being accessed at least
1013 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 1K 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 6 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.
Document Number: 001-86148 Rev. *C
F-RAM read and write endurance is virtually unlimited even at a
4 MHz clock rate.
Table 6. Time to Reach Endurance Limit for Repeating
64-byte Loop
SCK Freq
(MHz)
Endurance
Cycles/sec
Endurance
Cycles/year
Years to Reach
Limit
4
7,480
2.36 × 1011
42.3
1,870
10
1
5.88 × 10
170.1
Page 10 of 20
FM25640B
Maximum Ratings
Exceeding maximum ratings may shorten the useful life of the
device. These user guidelines are not tested.
Storage temperature ................................ –55 C to +150 C
Package power dissipation
capability (TA = 25 °C) ................................................. 1.0 W
Surface mount lead soldering
temperature (3 seconds) ......................................... +260 C
DC output current (1 output at a time, 1s duration) .... 15 mA
Maximum accumulated storage time
At 150 °C ambient temperature ................................. 1000 h
At 125 °C ambient temperature ................................11000 h
At 85 °C ambient temperature .............................. 121 Years
Electrostatic Discharge Voltage
Human Body Model (AEC-Q100-002 Rev. E) ....................... 4 kV
Charged Device Model (AEC-Q100-011 Rev. B) .............. 1.25 kV
Machine Model (AEC-Q100-003 Rev. E) .............................. 300 V
Ambient temperature
with power applied ................................... –55 °C to +125 °C
Latch up current ..................................................... > 140 mA
Supply voltage on VDD relative to VSS .........–1.0 V to +7.0 V
Operating Range
Input voltage ............. –1.0 V to +7.0 V and VIN < VDD+1.0 V
DC voltage applied to outputs
in High Z state .................................... –0.5 V to VDD + 0.5 V
Range
Ambient Temperature (TA)
VDD
–40 C to +125 C
4.5 V to 5.5 V
Automotive-E
Transient voltage (< 20 ns) on
any pin to ground potential ................. –2.0 V to VDD + 2.0 V
DC Electrical Characteristics
Over the Operating Range
Parameter
VDD
Power supply
IDD
VDD supply current
ISB
Min
Typ [3]
Max
Unit
4.5
5.0
5.5
V
SCK toggling between fSCK = 1 MHz
VDD – 0.3 V and VSS,
fSCK = 4 MHz
other inputs
VSS or VDD – 0.3 V.
SO = Open.
–
–
0.3
mA
–
–
1.2
mA
CS = VDD. All other TA = 85 °C
inputs VSS or VDD.
TA = 125 °C
–
–
10
A
–
–
30
A
Description
VDD standby current
Test Conditions
ILI
Input leakage current
VSS < VIN < VDD
–
–
±1
A
ILO
Output leakage current
VSS < VOUT < VDD
–
–
±1
A
VIH
Input HIGH voltage
0.75 × VDD
–
VDD + 0.3
V
VIL
Input LOW voltage
– 0.3
–
0.25 × VDD
V
VOH
Output HIGH voltage
IOH = –2 mA
VDD – 0.8
–
–
V
VOL
Output LOW voltage
IOL = 2 mA
–
–
0.4
V
VHYS[4]
Input Hysteresis (CS and SCK pin)
0.05 × VDD
–
–
V
Notes
3. Typical values are at 25 °C, VDD = VDD(typ). Not 100% tested.
4. This parameter is characterized but not 100% tested.
Document Number: 001-86148 Rev. *C
Page 11 of 20
FM25640B
Data Retention and Endurance
Parameter
TDR
NVC
Description
Test condition
TA = 125 C
Data retention
Endurance
Min
Max
Unit
11000
–
Hours
Years
TA = 105 C
11
–
TA = 85 C
121
–
Over operating temperature
1013
–
Cycles
Example of an F-RAM Life Time in an AEC-Q100 Automotive Application
An application does not operate under a steady temperature for the entire usage life time of the application. Instead, it is often expected
to operate in multiple temperature environments throughout the application’s usage life time. Accordingly, the retention specification
for F-RAM in applications often needs to be calculated cumulatively. An example calculation for a multi-temperature thermal profiles
is given below.
Acceleration Factor with respect to Tmax
A [5]
Tempeature
T
Time Factor
t
T1 = 125 C
T2 = 105 C
T3 = 85 C
T4 = 55 C
LT
A = ------------------------ = e
L Tmax
t1 = 0.1
t2 = 0.15
t3 = 0.25
t4 = 0.50
1
Ea 1 --------------------- --- –
k T Tmax
Profile Factor
P
Profile Life Time
L (P)
1
P = -------------------------------------------------------t1- -----t2- -----t3- -----t4-
----- A1 + A2 + A3 + A4
L P = P L Tmax
8.33
> 10.46 Years
A1 = 1
A2 = 8.67
A3 = 95.68
A4 = 6074.80
Capacitance
Parameter [6]
Description
CO
Output pin capacitance (SO)
CI
Input pin capacitance
Test Conditions
Max
Unit
8
pF
6
pF
Test Conditions
8-pin SOIC
Unit
Test conditions follow standard test methods and
procedures for measuring thermal impedance, per EIA /
JESD51.
147
C/W
47
C/W
TA = 25 C, f = 1 MHz, VDD = VDD(typ)
Thermal Resistance
Parameter
JA
JC
Description
Thermal resistance
(junction to ambient)
Thermal resistance
(junction to case)
AC Test Conditions
Input pulse levels .................................10% and 90% of VDD
Input rise and fall times ...................................................5 ns
Input and output timing reference levels ................0.5 × VDD
Output load capacitance .............................................. 30 pF
Notes
5. Where k is the Boltzmann constant 8.617 × 10-5 eV/K, Tmax is the highest temperature specified for the product, and T is any temperature within the F-RAM product
specification. All temperatures are in Kelvin in the equation.
6. This parameter is characterized but not 100% tested.
Document Number: 001-86148 Rev. *C
Page 12 of 20
FM25640B
AC Switching Characteristics
Over the Operating Range
Parameters [7]
Cypress
Parameter
Description
Alt. Parameter
Min
Max
Unit
0
4
MHz
fSCK
–
SCK Clock frequency
tCH
–
Clock HIGH time
100
–
ns
tCL
–
Clock LOW time
100
–
ns
tCSU
tCSS
Chip select setup
100
–
ns
tCSH
tCSH
Chip select hold
100
–
ns
tHZCS
Output disable time
–
100
ns
tODV
tCO
Output data valid time
–
75
ns
tOH
–
Output hold time
0
–
ns
tD
100
–
ns
tOD
[8, 9]
–
Deselect time
[10, 11]
–
Data in rise time
–
50
ns
tF[10, 11]
–
Data in fall time
–
50
ns
tSU
tSD
Data setup time
30
–
ns
tH
tHD
Data hold time
20
–
ns
tHS
tSH
HOLD setup time
70
–
ns
tHH
tHH
HOLD hold time
40
–
ns
tHZ[8, 9]
tLZ[9]
tHHZ
HOLD LOW to HI-Z
–
100
ns
tHLZ
HOLD HIGH to data active
–
50
ns
tR
Notes
7. Test conditions assume a signal transition time of 5 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 12.
8. tOD and tHZ are specified with a load capacitance of 5 pF. Transition is measured when the outputs enter a high impedance state.
9. This parameter is characterized but not 100% tested.
10. Rise and fall times measured between 10% and 90% of waveform.
11. These parameters are guaranteed by design and are not tested.
Document Number: 001-86148 Rev. *C
Page 13 of 20
FM25640B
Figure 13. 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 14. HOLD Timing
tHS
~
~
tHS
VALID IN
tHZ
Document Number: 001-86148 Rev. *C
VALID IN
tLZ
~
~
SO
tSU
~
~
HOLD
SI
tHH
Page 14 of 20
FM25640B
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 [12]
VDD power-up ramp rate
30
–
µs/V
tVF [12]
VDD power-down ramp rate
20
–
µs/V
VDD
~
~
Figure 15. Power Cycle Timing
VDD(min)
tVR
CS
tVF
tPD
~
~
tPU
VDD(min)
Note
12. Slope measured at any point on VDD waveform.
Document Number: 001-86148 Rev. *C
Page 15 of 20
FM25640B
Ordering Information
Package
Diagram
Ordering Code
Package Type
FM25640B-GA
51-85066 8-pin SOIC
FM25640B-GATR
51-85066 8-pin SOIC
Operating
Range
Automotive-E
All these parts are Pb-free. Contact your local Cypress sales representative for availability of these parts.
Ordering Code Definitions
FM 25 640 B
-
G
A TR
Option:
blank = Standard; TR = Tape and Reel
Temperature Range:
A = Automotive-E (–40 C to +125 C)
Package Type:
G = 8-pin SOIC
Die revision: B
Density: 640 = 64-Kbit
SPI F-RAM
Cypress
Document Number: 001-86148 Rev. *C
Page 16 of 20
FM25640B
Package Diagram
Figure 16. 8-pin SOIC (150 Mils) Package Outline, 51-85066
51-85066 *G
Document Number: 001-86148 Rev. *C
Page 17 of 20
FM25640B
Acronyms
Acronym
Document Conventions
Description
Units of Measure
AEC
Automotive Electronics Council
CPHA
Clock Phase
°C
degree Celsius
CPOL
Clock Polarity
Hz
hertz
EEPROM
Electrically Erasable Programmable Read-Only
Memory
kHz
kilohertz
K
kilohm
Kbit
kilobit
kV
kilovolt
MHz
megahertz
A
microampere
s
microsecond
mA
milliampere
ms
millisecond
ns
nanosecond
ohm
%
percent
pF
picofarad
V
volt
W
watt
EIA
Electronic Industries Alliance
I/O
Input/Output
JEDEC
Joint Electron Devices Engineering Council
JESD
JEDEC Standards
LSB
Least Significant Bit
MSB
Most Significant Bit
F-RAM
Ferroelectric Random Access Memory
RoHS
Restriction of Hazardous Substances
SPI
Serial Peripheral Interface
SOIC
Small Outline Integrated Circuit
Document Number: 001-86148 Rev. *C
Symbol
Unit of Measure
Page 18 of 20
FM25640B
Document History Page
Document Title: FM25640B, 64-Kbit (8 K × 8) Serial (SPI) Automotive F-RAM
Document Number: 001-86148
Rev.
ECN No.
Orig. of
Change
Submission
Date
**
3912930
GVCH
02/25/2013
New data sheet.
*A
4227122
GVCH
01/24/2014
Converted to Cypress standard format
Updated Maximum Ratings table
- Removed Moisture Sensitivity Level (MSL)
- Added junction temperature and latch up current
Updated Data Retention and Endurance table
Added “Example of an F-RAM Life Time in an AEC-Q100 Automotive Application” table
Added footnote 5
Added Thermal Resistance table
Removed Package Marking Scheme (top mark)
Removed Ramtron revision history
Completing Sunset Review.
*B
4724164
PSR
04/14/2015
Updated Functional Description:
Added “For a complete list of related resources, click here.” at the end.
Updated Package Diagram:
spec 51-85066 – Changed revision from *F to *G.
Updated to new template.
*C
4884720
ZSK / PSR
08/14/2015
Updated Maximum Ratings:
Updated ratings of “Storage temperature” (Replaced “+125 °C” with “+150 C”).
Removed “Maximum junction temperature”.
Added “Maximum accumulated storage time”.
Added “Ambient temperature with power applied”.
Document Number: 001-86148 Rev. *C
Description of Change
Page 19 of 20
FM25640B
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
Memory
PSoC
Touch Sensing
USB Controllers
Wireless/RF
cypress.com/go/automotive
cypress.com/go/clocks
cypress.com/go/interface
cypress.com/go/powerpsoc
psoc.cypress.com/solutions
PSoC 1 | PSoC 3 | PSoC 4 | PSoC 5LP
Cypress Developer Community
Community | Forums | Blogs | Video | Training
cypress.com/go/memory
cypress.com/go/psoc
cypress.com/go/touch
Technical Support
cypress.com/go/support
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: 001-86148 Rev. *C
Revised August 14, 2015
All products and company names mentioned in this document may be the trademarks of their respective holders.
Page 20 of 20
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