FM25V20-DGTR [CYPRESS]

2Mb Serial 3V F-RAM Memory; 2MB串行3V F-RAM存储器
FM25V20-DGTR
型号: FM25V20-DGTR
厂家: CYPRESS    CYPRESS
描述:

2Mb Serial 3V F-RAM Memory
2MB串行3V F-RAM存储器

存储
文件: 总17页 (文件大小:531K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
FM25V20  
2Mb Serial 3V F-RAM Memory  
Features  
Device ID  
2M bit Ferroelectric Nonvolatile RAM  
Device ID reads out Manufacturer ID & Part ID  
Organized as 256K x 8 bits  
High Endurance 100 Trillion (1014) Read/Writes  
10 Year Data Retention  
Low Voltage, Low Power  
Low Voltage Operation 2.0V 3.6V  
100 A Standby Current (typ.)  
3 A Sleep Mode Current (typ.)  
NoDelay™ Writes  
Advanced High-Reliability Ferroelectric Process  
Very Fast Serial Peripheral Interface - SPI  
Industry Standard Configurations  
Up to 40 MHz Frequency  
Direct Hardware Replacement for Serial Flash  
SPI Mode 0 & 3 (CPOL, CPHA=0,0 & 1,1)  
Industrial Temperature -40C to +85C  
8-pin “Green”/RoHS EIAJ SOIC Package  
8-pin “Green”/RoHS TDFN Package  
8-pin “Green”/POHS PDIP Package  
Write Protection Scheme  
Hardware Protection  
Software Protection  
Device ID that allows the host to determine the  
manufacturer, product density, and product revision.  
The device is guaranteed over an industrial  
temperature range of -40°C to +85°C.  
Description  
The FM25V20 is a 2-megabit nonvolatile memory  
employing an advanced ferroelectric process. A  
ferroelectric random access memory or F-RAM is  
nonvolatile and performs reads and writes like a  
RAM. It provides reliable data retention for 10 years  
while eliminating the complexities, overhead, and  
system level reliability problems caused by Serial  
Flash and other nonvolatile memories.  
Pin Configuration  
Top View  
/S  
Q
VDD  
/HOLD  
C
1
2
3
4
8
7
6
5
Unlike Serial Flash, the FM25V20 performs write  
operations at bus speed. No write delays are incurred.  
Data is written to the memory array immediately  
after it has been transferred to the device. The next  
bus cycle may commence without the need for data  
polling. The product offers very high write  
endurance, orders of magnitude more endurance than  
Serial Flash. Also, F-RAM exhibits lower power  
consumption than Serial Flash.  
/W  
VSS  
D
1
8
7
6
5
S
Q
VDD  
HOLD  
C
2
3
4
W
VSS  
D
These capabilities make the FM25V20 ideal for  
nonvolatile memory applications requiring frequent  
or rapid writes or low power operation. Examples  
range from data collection, where the number of  
write cycles may be critical, to demanding controls  
where the long write time of Serial Flash can cause  
data loss.  
Pin Name  
/S  
/W  
/HOLD  
C
D
Q
VDD  
VSS  
Function  
Chip Select  
Write Protect  
Hold  
Serial Clock  
Serial Data Input  
Serial Data Output  
Supply Voltage  
Ground  
The FM25V20 provides substantial benefits to users  
of Serial Flash as a hardware drop-in replacement.  
The device uses the high-speed SPI bus, which  
enhances the high-speed write capability of F-RAM  
technology. The device incorporates a read-only  
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.  
Ramtron International Corporation  
1850 Ramtron Drive, Colorado Springs, CO 80921  
(800) 545-FRAM, (719) 481-7000  
http://www.ramtron.com  
Rev. 3.0  
August 2012  
Page 1 of 17  
FM25V20 2Mb SPI F-RAM  
W
S
Instruction Decode  
Clock Generator  
Control Logic  
HOLD  
C
Write Protect  
32K x 64  
FRAM Array  
Instruction Register  
18  
8
Address Register  
Counter  
Q
D
Data I/O Register  
3
Nonvolatile Status  
Register  
Figure 1. Block Diagram  
Pin Descriptions  
Pin Name  
I/O  
Description  
/S  
Input  
Chip Select: This active-low input activates the device. When high, the device enters  
low-power standby mode, ignores other inputs, and all outputs are tri-stated. When  
low, the device internally activates the C signal. A falling edge on /S must occur prior  
to every op-code.  
C
Input  
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. Since the device is static, the  
clock frequency may be any value between 0 and 40 MHz and may be interrupted at  
any time.  
Hold: 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 C or /S. All transitions on /HOLD must occur while C is low.  
/HOLD  
If it is not used, the /HOLD pin should be tied to VDD  
.
/W  
D
Input  
Input  
Write Protect: This active-low pin prevents write operations to the Status Register  
only. A complete explanation of write protection is provided on pages 6 and 7. If it is  
not used, the /W pin should be tied to VDD  
.
Serial Input: All data is input to the device on this pin. The pin is sampled on the  
rising edge of C and is ignored at other times. It should always be driven to a valid  
logic level to meet IDD specifications.  
* D may be connected to Q for a single pin data interface.  
Serial Output: This is the data output pin. It is driven during a read and remains tri-  
stated at all other times including when /HOLD is low. Data transitions are driven on  
the falling edge of the serial clock.  
Q
Output  
* Q may be connected to D for a single pin data interface.  
VDD  
VSS  
Supply  
Supply  
Power Supply  
Ground  
Rev. 3.0  
August 2012  
Page 2 of 17  
FM25V20 2Mb SPI F-RAM  
Protocol Overview  
Overview  
The SPI interface is a synchronous serial interface  
using clock and data pins. It is intended to support  
multiple devices on the bus. Each device is activated  
using a chip select. Once chip select is activated by  
the bus master, the FM25V20 will begin monitoring  
the clock and data lines. The relationship between the  
falling edge of /S, the clock and data is dictated by  
the SPI mode. The device will make a determination  
of the SPI mode on the falling edge of each chip  
select. While there are four such modes, the  
FM25V20 supports only modes 0 and 3. Figure 2  
shows the required signal relationships for modes 0  
and 3. For both modes, data is clocked into the  
FM25V20 on the rising edge of C and data is  
expected on the first rising edge after /S goes active.  
If the clock starts from a high state, it will fall prior to  
the first data transfer in order to create the first rising  
edge.  
The FM25V20 is a serial F-RAM memory. The  
memory array is logically organized as 262,144 x 8  
and is accessed using an industry standard Serial  
Peripheral Interface or SPI bus. Functional operation  
of the F-RAM is similar to Serial Flash. The major  
differences between the FM25V20 and a Serial Flash  
with the same pinout are the F-RAM’s superior write  
performance, very high endurance, and lower power  
consumption.  
Memory Architecture  
When accessing the FM25V20, the user addresses  
256K locations of 8 data bits each. These data bits are  
shifted serially. The addresses are accessed using the  
SPI protocol, which includes a chip select (to permit  
multiple devices on the bus), an op-code, and a three-  
byte address. The complete address of 18-bits  
specifies each byte address uniquely.  
The SPI protocol is controlled by op-codes. These  
op-codes specify the commands to the device. After  
/S is activated the first byte transferred from the bus  
master is the op-code. Following the op-code, any  
addresses and data are then transferred.  
Most functions of the FM25V20 either are controlled  
by the SPI interface or are handled automatically by  
on-board circuitry. The access time for 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 Serial  
Flash, it is not necessary to poll the device for a ready  
condition since writes occur at bus speed. So, by the  
time a new bus transaction can be shifted into the  
device, a write operation will be complete. This is  
explained in more detail in the interface section.  
Certain op-codes are commands with no subsequent  
data transfer. The /S must go inactive after an  
operation is complete and before a new op-code can  
be issued. There is one valid op-code only per active  
chip select.  
SPI Mode 0: CPOL=0, CPHA=0  
Users expect several obvious system benefits from  
the FM25V20 due to its fast write cycle and high  
endurance as compared to Serial Flash. In addition  
there are less obvious benefits as well. For example  
in a high noise environment, the fast-write operation  
is less susceptible to corruption than Serial Flash  
since it is completed quickly. By contrast, Serial  
Flash requiring milliseconds to write is vulnerable to  
noise during much of the cycle.  
S
C
D
7
6
5
4
3
2
1
0
MSB  
LSB  
Serial Peripheral Interface SPI Bus  
SPI Mode 3: CPOL=1, CPHA=1  
The FM25V20 employs a Serial Peripheral Interface  
(SPI) bus. It is specified to operate at speeds up to  
40MHz. This high-speed serial bus provides high  
S
performance serial communication to  
a
host  
C
microcontroller. 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.  
D
7
6
5
4
3
2
1
0
MSB  
LSB  
Figure 2. SPI Modes 0 & 3  
Rev. 3.0  
August 2012  
Page 3 of 17  
FM25V20 2Mb SPI F-RAM  
System Hookup  
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 together and tie off the  
Hold pin. Figure 4 shows a configuration that uses  
only three pins.  
The SPI interface uses a total of four pins: clock,  
data-in, data-out, and chip select. A typical system  
configuration uses one or more FM25V20 devices  
with a microcontroller that has a dedicated SPI port,  
as Figure 3 illustrates. Note that the clock, data-in,  
and data-out pins are common among all devices.  
The Chip Select and Hold pins must be driven  
separately for each FM25V20 device.  
SCK  
MOSI  
MISO  
Q
D
C
Q
D
C
SPI  
FM25V20  
HOLD  
FM25V20  
S HOLD  
Microcontroller  
S
SS1  
SS2  
HOLD1  
HOLD2  
MOSI : Master Out Slave In  
MISO : Master In Slave Out  
SS : Slave Select  
Figure 3. 4Mbit (512KB) System Configuration with SPI port  
P1.0  
P1.1  
Q
D
C
Microcontroller  
FM25V20  
HOLD  
S
VDD  
P1.2  
Figure 4. System Configuration without SPI port  
Rev. 3.0  
August 2012  
Page 4 of 17  
FM25V20 2Mb SPI F-RAM  
without another WREN command. Figure 5 below  
illustrates the WREN command bus configuration.  
Power Up to First Access  
The FM25V20 is not accessible for a period of time  
(tPU) after power up. Users must comply with the  
timing parameter tPU, which is the minimum time  
from VDD (min) to the first /S low.  
S
0
0
1
0
2
0
3
0
4
0
5
1
6
1
7
0
C
Data Transfer  
All data transfers to and from the FM25V20 occur in  
8-bit groups. They are synchronized to the clock  
signal (C), and they transfer most significant bit  
(MSB) first. Serial inputs are registered on the rising  
edge of C. Outputs are driven from the falling edge of  
clock C.  
D
Q
Hi-Z  
Figure 5. WREN Bus Configuration  
Command Structure  
There are nine commands called op-codes that can be  
issued by the bus master to the FM25V20. They are  
listed in the table below. These op-codes control the  
functions performed by the memory. They can be  
divided into three categories. First, there are  
commands that have no subsequent operations. They  
perform a single function, such as to enable a write  
operation. Second are commands followed by one  
byte, either in or out. They operate on the Status  
Register. The third group includes commands for  
memory transactions followed by address and one or  
more bytes of data.  
WRDI Write Disable  
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=0.  
Figure 6 illustrates the WRDI command bus  
configuration.  
S
0
0
1
0
2
0
3
4
5
1
6
0
7
0
C
Table 1. Op-code Commands  
Name  
Description  
Op-code  
00000110b  
00000100b  
00000101b  
00000001b  
00000011b  
00001011b  
00000010b  
10111001b  
10011111b  
Set Write Enable Latch  
WREN  
WRDI  
RDSR  
WRSR  
READ  
FSTRD  
WRITE  
SLEEP  
RDID  
0
0
D
Q
Write Disable  
Read Status Register  
Write Status Register  
Read Memory Data  
Fast Read Memory Data  
Write Memory Data  
Enter Sleep Mode  
Read Device ID  
Hi-Z  
Figure 6. WRDI Bus Configuration  
RDSR Read Status Register  
The RDSR command allows the bus master to  
verify the contents of the Status Register. Reading  
Status provides information about the current state  
of the write protection features. Following the  
RDSR op-code, the FM25V20 will return one byte  
with the contents of the Status Register. The Status  
Register is described in detail in the section below.  
WREN Set Write Enable Latch  
The FM25V20 will power up with writes disabled.  
The WREN command must be issued prior to any  
write operation. Sending the WREN op-code will  
allow the user to issue subsequent op-codes for write  
operations. These include writing the Status Register  
(WRSR) and writing the memory (WRITE).  
Sending the WREN op-code 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.  
Completing any write operation will automatically  
clear the write-enable latch and prevent further writes  
Rev. 3.0  
August 2012  
Page 5 of 17  
FM25V20 2Mb SPI F-RAM  
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  
configuration of RDSR and WRSR are shown  
below.  
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 issuing a WRSR  
command, the /W pin must be high or inactive. Prior  
S
C
D
Q
Figure 7. RDSR Bus Configuration  
S
C
D
Q
Figure 8. WRSR Bus Configuration  
Register has no effect on its state. This bit is  
internally set and cleared via the WREN and WRDI  
commands, respectively.  
Status Register & Write Protection  
The write protection features of the FM25V20 are  
multi-tiered. Taking the /W pin to a logic low state is  
the hardware write-protect function. Status Register  
write operations are blocked when /W is low. To  
write the memory with /W high, a WREN op-code  
must first be issued. Assuming that writes are enabled  
using WREN and by /W, writes to memory are  
controlled by the Status Register. As described  
above, writes to the Status Register are performed  
using the WRSR command and subject to the /W pin.  
The Status Register is organized as follows.  
BP1 and BP0 are memory block write protection bits.  
They specify portions of memory that are write-  
protected as shown in the following table.  
Table 3. Block Memory Write Protection  
BP1  
BP0 Protected Address Range  
0
0
1
1
0
1
0
1
None  
30000h to 3FFFFh (upper ¼)  
20000h to 3FFFFh (upper ½)  
00000h to 3FFFFh (all)  
Table 2. Status Register  
7
6
1
5
0
4
0
3
2
1
0
0
Bit  
WPEN  
BP1  
BP0  
WEL  
Name  
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.  
Bits 0, 4, 5 are fixed at 0 and bit 6 is fixed at 1, and  
none of these bits can be modified. Note that bit 0  
(Readyin Serial Flash) is unnecessary as the F-  
RAM writes in real-time and is never busy, so it  
reads out as a ‘0’. There is an exception to this when  
the device is waking up from Sleep Mode, which is  
described in the Sleep Mode section. The BP1 and  
BP0 control software write protection features. They  
are nonvolatile (shaded yellow). The WEL flag  
indicates the state of the Write Enable Latch.  
Attempting to directly write the WEL bit in the Status  
The WPEN bit controls the effect of the hardware /W  
pin. When WPEN is low, the /W pin is ignored.  
When WPEN is high, the /W pin controls write  
access to the Status Register. Thus the Status Register  
is write protected if WPEN=1 and /W=0.  
This scheme provides a write protection mechanism,  
which can prevent software from writing the memory  
Rev. 3.0  
August 2012  
Page 6 of 17  
FM25V20 2Mb SPI F-RAM  
under any circumstances. This occurs if the BP1 and  
BP0 bits are set to 1, the WPEN bit is set to 1, and  
the /W pin is low. This occurs because the block  
protect bits prevent writing memory and the /W  
signal in hardware prevents altering the block protect  
bits (if WPEN is high). Therefore in this condition,  
hardware must be involved in allowing a write  
operation. The following table summarizes the write  
protection conditions.  
Table 4. Write Protection  
WEL  
WPEN  
/W  
X
X
0
Protected Blocks  
Protected  
Protected  
Protected  
Protected  
Unprotected Blocks  
Protected  
Unprotected  
Unprotected  
Unprotected  
Status Register  
Protected  
Unprotected  
Protected  
0
1
1
1
X
0
1
1
1
Unprotected  
one bit read out for each. Addresses are incremented  
internally as long as the bus master continues to issue  
clocks. If the last address of 3FFFFh is reached, the  
counter will roll over to 00000h. Data is read MSB  
first. The rising edge of /S terminates a READ op-  
code operation and tri-states the Q pin. A read  
operation is shown in Figure 10.  
Memory Operation  
The SPI interface, which is capable of a relatively  
high clock frequency, highlights the fast write  
capability of the F-RAM technology. Unlike Serial  
Flash, the FM25V20 can perform sequential writes at  
bus speed. No page buffer is needed and any number  
of sequential writes may be performed.  
Fast Read Operation  
Write Operation  
The FM25V20 supports the FAST READ op-code  
(0Bh) that is found on Serial Flash devices. It is  
implemented for code compatibility with Serial Flash  
devices. Following this instruction is a three-byte  
address (A17-A0), specifying the address of the first  
data byte of the read operation. A dummy address  
byte follows the address. It inserts one byte of read  
latency. The D pin is ignored after the op-code, three-  
byte address, and dummy byte are complete. The bus  
master issues 8 clocks, with one bit read out for each.  
The Fast Read operation is otherwise the same as an  
ordinary READ. If the last address of 3FFFFh is  
reached, the counter will roll over to 00000h. Data is  
read MSB first. The rising edge of /S terminates a  
FAST READ op-code operation and tri-states the Q  
pin. A Fast Read operation is shown in Figure 11.  
All writes to the memory array begin with a WREN  
op-code. The next op-code is the WRITE instruction.  
This op-code is followed by a three-byte address  
value, which specifies the 18-bit address of the first  
data byte of the write operation. Subsequent bytes are  
data and they are written sequentially. Addresses are  
incremented internally as long as the bus master  
continues to issue clocks. If the last address of  
3FFFFh is reached, the counter will roll over to  
00000h. Data is written MSB first. A write operation  
is shown in Figure 9.  
Unlike Serial Flash, any number of bytes can be  
written sequentially and each byte is written to  
memory immediately after it is clocked in (after the  
8th clock). The rising edge of /S terminates a WRITE  
op-code operation. Asserting /W active in the middle  
of a write operation will have no effect until the next  
falling edge of /S.  
Hold  
The FM25V20 device has a /HOLD pin that can be  
used to interrupt a serial operation without aborting  
it. If the bus master pulls the /HOLD pin low while C  
is low, the current operation will pause. Taking the  
/HOLD pin high while C is low will resume an  
operation. The transitions of /HOLD must occur  
while C is low, but the C and /S pins can toggle  
during a hold state.  
Read Operation  
After the falling edge of /S, the bus master can issue  
a READ op-code. Following this instruction is a  
three-byte address value (A17-A0), specifying the  
address of the first data byte of the read operation.  
After the op-code and address are complete, the D  
pin is ignored. The bus master issues 8 clocks, with  
Rev. 3.0  
August 2012  
Page 7 of 17  
FM25V20 2Mb SPI F-RAM  
S
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
4
5
6
7
0
1
2
3
4
5
6
7
C
D
op-code  
18-bit Address  
Data  
A3 A2 A1 A0  
LSB MSB  
0
0
0
0
0
0
A17 A16  
7
6
5
4
3
2
1
0
0
0
0
0
0
0
1
0
MSB  
LSB  
Q
Figure 9. Memory Write with 3-Byte Address  
S
0
1
2
3
4
5
6
7
0
1
2
3
4
6
7
4
5
6
7
0
1
2
3
4
5
6
7
5
C
D
18-bit Address  
op-code  
A17 A16  
A3 A2 A1 A0  
LSB  
0
0
0
0
0
0
0
0
0
0
0
0
1
1
MSB  
Data  
MSB  
7
LSB  
0
Q
6
5
4
3
2
1
Figure 10. Memory Read with 3-Byte Address  
S
0
1
2
3
4
5
6
7
0
1
2
3
6
7
4
5
6
7
0
1
2
3
4
5
6
7
5
C
D
Dummy byte  
op-code  
18-bit Address  
0
0
0
0
A2 A1 A0  
X
X
X
X
0
0
0
0
1
0
1
1
MSB  
LSB  
Data  
MSB  
7
LSB  
0
Q
6
5
4
3
2
1
Figure 11. Fast Read with 3-Byte Address and Dummy Byte  
Rev. 3.0  
August 2012  
Page 8 of 17  
FM25V20 2Mb SPI F-RAM  
Sleep Mode  
Enter Sleep  
Mode  
A
low power mode called Sleep Mode is  
implemented on the FM25V20 device. The device  
will enter this low power state when the SLEEP op-  
code B9h is clocked-in and a rising edge of /S is  
applied. Once in sleep mode, the C and D pins are  
ignored and Q will be high-Z, but the device  
continues to monitor the /S pin. On the next falling  
edge of /S, the device will return to normal operation  
within tREC (400 s max.). The Q pin remains in a hi-  
Z state during the wakeup period. The device will 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.  
S
C
D
Q
Figure 12. Sleep Mode Entry  
Device ID  
The FM25V20 device can be interrogated for its manufacturer, product identification, and die revision. The RDID  
op-code 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 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 Product Revision code.  
Table 5. Manufacturer and Product ID  
Bit  
7
0
0
0
0
0
0
1
6
1
1
1
1
1
1
1
5
1
1
1
1
1
1
0
4
1
1
1
1
1
1
0
3
1
1
1
1
1
1
0
2
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
0
Hex  
7F  
7F  
7F  
7F  
7F  
7F  
C2  
Manufacturer ID  
Continuation code  
Continuation code  
Continuation code  
Continuation code  
Continuation code  
Continuation code  
JEDEC assigned Ramtron C2h in bank 7  
Family  
0
Sub  
Density  
Hex  
25h  
Device ID (1st Byte)  
Device ID (2nd Byte)  
0
1
0
0
Rev.  
0
0
1
0
1
0
Density: 03h=512K, 04h=1M, 05h=2M, 06h=4M  
00h=FM25V20  
Rsvd  
0
0
0
0
0
00h  
S
C
. . . . . . .  
D
Q
9Fh  
C2h  
25h  
7Fh  
7Fh  
6
00h  
1
Six bytes of continuation code 7Fh  
Figure 13. Read Device ID  
Rev. 3.0  
August 2012  
Page 9 of 17  
FM25V20 - 2Mb SPI F-RAM  
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. The table below shows  
endurance calculations for 64-byte repeating loop,  
which includes an op-code, 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 40MHz clock rate.  
Endurance  
The FM25V20 device is 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. Rows are defined by A17-A3  
and column addresses by A2-A0.  
See Block  
Diagram (pg 2) which shows the array as 32K rows  
Table 6. Time to Reach 100 Trillion Cycles for Repeating 64-byte Loop  
SCK Freq Endurance Endurance Years to Reach  
(MHz) Cycles/sec.  
1014 Cycles  
Cycles/year  
2.32 x 1012  
5.79 x 1011  
2.90 x 1011  
43.1  
172.7  
345.4  
40  
10  
5
73,520  
18,380  
9,190  
Rev. 3.0  
August 2012  
Page 10 of 17  
FM25V20 - 2Mb SPI F-RAM  
Electrical Specifications  
Absolute Maximum Ratings  
Symbol  
VDD  
VIN  
Description  
Power Supply Voltage with respect to VSS  
Voltage on any pin with respect to VSS  
Ratings  
-1.0V to +4.5V  
-1.0V to +4.5V  
and VIN < VDD+1.0V  
-55C to + 125C  
260C  
TSTG  
TLEAD  
VESD  
Storage Temperature  
Lead Temperature (Soldering, 10 seconds)  
Electrostatic Discharge Voltage  
- Human Body Model (JEDEC Std JESD22-A114-B)  
- Charged Device Model (JEDEC Std JESD22-C101-A)  
- Machine Model (JEDEC Std JESD22-A115-A)  
Package Moisture Sensitivity Level  
4kV  
1.25kV  
250V  
MSL-1  
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating  
only, and the functional operation of the device at these or any other conditions above those listed in the operational section of this  
specification is not implied. Exposure to absolute maximum ratings conditions for extended periods may affect device reliability.  
DC Operating Conditions (TA = -40C to + 85C, VDD = 2.0V to 3.6V unless otherwise specified)  
Symbol Parameter  
Min  
Typ  
Max  
Units  
Notes  
VDD  
IDD  
Power Supply Voltage  
Power Supply Operating Current  
@ C = 1 MHz  
2.0  
3.3  
3.6  
V
1
0.13  
1.4  
0.30  
3.0  
mA  
mA  
@ C = 40 MHz  
ISB  
Standby Current  
@ TA = 25°C  
@ TA = 85°C  
Sleep Mode Current  
2
3
A  
A  
100  
-
150  
250  
IZZ  
A  
A  
@ TA = 25°C  
@ TA = 85°C  
3
-
5
8
ILI  
ILO  
VIH  
Input Leakage Current  
Output Leakage Current  
Input High Voltage  
-
-
A  
A  
V
4
4
1  
1  
VDD + 0.3  
0.7 VDD  
VIL  
Input Low Voltage  
-0.3  
0.3 VDD  
V
VOH1  
VOH2  
VOL1  
VOL2  
Notes  
Output High Voltage (IOH = -1 mA, VDD=2.7V)  
Output High Voltage (IOH = -100 A)  
Output Low Voltage (IOL = 2 mA, VDD=2.7V)  
Output Low Voltage (IOL = 150 A)  
2.4  
VDD-0.2  
-
-
0.4  
0.2  
V
V
V
V
-
-
1. C toggling between VDD-0.2V and VSS, other inputs VSS or VDD-0.2V. Q=open.  
2. /S=VDD. All inputs VSS or VDD  
3. In Sleep mode and /S=VDD. All inputs VSS or VDD  
.
.
4. VSS VIN VDD and VSS VOUT VDD  
.
Data Retention (TA = -40C to + 85C)  
Symbol  
TDR  
Parameter  
Data Retention  
Min  
10  
Max  
-
Units  
Years  
Notes  
Rev. 3.0  
August 2012  
Page 11 of 17  
FM25V20 2Mb SPI F-RAM  
AC Parameters (TA = -40C to + 85C, CL = 30pF, unless otherwise specified)  
VDD 2.0 to 2.7V VDD 2.7 to 3.6V  
Symbol  
fCK  
tCH  
tCL  
tCSU  
tCSH  
tOD  
tODV  
tOH  
tD  
Parameter  
Min  
0
20  
20  
12  
12  
Max  
25  
Min  
0
11  
11  
10  
10  
Max  
40  
Units  
MHz  
ns  
ns  
ns  
ns  
ns  
ns  
ns  
Notes  
C Clock Frequency  
Clock High Time  
Clock Low Time  
Chip Select Setup  
Chip Select Hold  
Output Disable Time  
Output Data Valid Time  
Output Hold Time  
Deselect Time  
1
1
20  
18  
12  
9
3
3
0
60  
0
40  
ns  
tR  
tF  
tSU  
tH  
Data In Rise Time  
Data In Fall Time  
Data Setup Time  
50  
50  
50  
50  
ns  
ns  
ns  
ns  
2,4  
2,4  
8
8
5
5
Data Hold Time  
tHS  
/HOLD Setup Time  
/HOLD Hold Time  
/HOLD Low to Hi-Z  
/HOLD High to Data Active  
12  
12  
10  
10  
ns  
ns  
ns  
ns  
tHH  
tHZ  
tLZ  
3
4
4
25  
25  
20  
20  
Notes  
1. tCH + tCL = 1/fCK  
.
2. Rise and fall times measured between 10% and 90% of waveform.  
3. Guaranteed by design.  
4. Guaranteed by design for 1MHz fCK.  
Capacitance (TA = 25C, f=1.0 MHz, VDD = 3.3V)  
Symbol Parameter  
Min  
Max  
Units  
Notes  
CO  
CI  
Output Capacitance (Q)  
Input Capacitance  
-
-
8
6
pF  
pF  
1
1
Notes  
1. Guaranteed by design.  
AC Test Conditions  
Input Pulse Levels  
10% and 90% of VDD  
3 ns  
50% of VDD  
30 pF  
Input rise and fall times  
Input and output timing levels  
Output Load Capacitance  
Serial Data Bus Timing  
tD  
S
tCL  
tCH  
tF  
tR  
tCSH  
tCSU  
1/tCK  
C
tH  
tSU  
D
Q
tOH  
tOD  
tODV  
/HOLD Timing  
Rev. 3.0  
August 2012  
Page 12 of 17  
FM25V20 2Mb SPI F-RAM  
tHS  
S
C
tHH  
tHH  
tHS  
HOLD  
Q
tHZ  
tLZ  
Power Cycle Timing  
VDD min.  
VDD  
tVR  
tVF  
tPD  
tPU  
S
Power Cycle & Sleep Timing (TA = -40C to + 85C, VDD = 2.0V to 3.6V, unless otherwise specified)  
Symbol Parameter  
Min  
50  
100  
1
0
-
Max  
-
-
-
-
Units  
s/V  
s/V  
ms  
s  
s  
Notes  
1
1
tVR  
tVF  
VDD Rise Time  
VDD Fall Time  
tPU  
tPD  
tREC  
Power Up (VDD min) to First Access (/S low)  
Last Access (/S high) to Power Down (VDD min)  
Recovery Time from Sleep Mode  
2
450  
Notes  
1. Slope measured at any point on VDD waveform.  
2. Guaranteed by design.  
Rev. 3.0  
August 2012  
Page 13 of 17  
FM25V20 2Mb SPI F-RAM  
Mechanical Drawing  
8-pin TDFN* (5.0 mm x 6.0 mm body, 1.27 mm pad pitch)  
Exposed metal pad  
should be left floating.  
5.0 BSC  
Pin 1 ID  
Pin 1  
0.60 ±0.05  
3.81 REF  
0.0 - 0.05  
0.20 REF.  
0.75 ±0.05  
Recommended PCB Footprint  
1.27  
1.4  
0.40 ±0.05  
6.80  
Silkscreen  
Pin 1  
0.60  
1.27  
Note: All dimensions in millimeters. This package is footprint compatible with the 8-pin SOIC.  
The exposed pad should be left floating.  
TDFN Package Marking Scheme for Body Size 5.0mm x 6.0mm  
Legend:  
R=Ramtron, G=”green” TDFN package  
XXXX=base part number, T=temperature (blank=ind., C=comm.)  
LLLL= lot code  
YY=year, WW=work week  
RGXXXXT  
LLLL  
YYWW  
Example: “Green” TDFN package, FM25V20, Lot 0012, Year 2010, Work Week 29  
RG5V20  
0012  
1029  
Rev. 3.0  
August 2012  
Page 14 of 17  
FM25V20 2Mb SPI F-RAM  
Mechanical Drawing  
8-pin DIP* JEDEC MS-001  
0.280 max  
0.240 min  
Index  
Area  
0.325 max  
0.300 min  
0.400 max  
0.355 min  
0.195 max  
0.115 min  
0.210  
max  
0.015 min  
0.005 min  
0.300 nom  
0.430 max  
0.022 max  
0.014 min  
0.100  
BSC  
Refer to JEDEC MS-001 for complete dimensions and notes.  
Controlling dimensions in inches.  
PDIP Package Marking Scheme  
Legend:  
XXXXX= part number, P=Package (P=PDIP “Green”),  
T=Temp. Range (C=commercial, <blank>=industrial)  
R=rev code, LLLLLLL= lot code  
RIC=Ramtron Int’l Corp, YY=year, WW=work week  
XXXXX-PT  
RLLLLLLL  
RICYYWW  
Example: FM25H20, “Green”/RoHS PDIP package,  
Rev. A, Lot 0448727, Year 2011, Work Week 03  
25H20-P  
A0448727  
RIC1103  
Rev. 3.0  
August 2012  
Page 15 of 17  
FM25V20 2Mb SPI F-RAM  
8-pin EIAJ SOIC  
Recommended PCB Footprint  
9.30  
5.00  
5.28 ±0.10 8.00 ±0.25  
2.15  
1.27  
0.65  
Pin 1  
5.23 ±0.10  
1.78  
2.00  
0.19  
0.25  
0.10 mm  
1.27  
0.05  
0.25  
0 - 8  
0.51  
0.76  
0.36  
0.50  
All dimensions in millimeters.  
EIAJ SOIC Package Marking Scheme  
Legend:  
XXXXXX= part number, P=package (G=”Green”), T=temp (blank=ind., C=comm.)  
R=rev code, LLLLLLL= lot code  
RIC=Ramtron Int’l Corp, YY=year, WW=work week  
XXXXXXX-PT  
RLLLLLLL  
RIC YYWW  
Example: FM25V20, “Green”/RoHS EIAJ SOIC package,  
Rev A, Lot 0448727, Year 2010, Work Week 29  
FM25V20-G  
A0448727  
RIC 1029  
Rev. 3.0  
August 2012  
Page 16 of 17  
FM25V20 2Mb SPI F-RAM  
Revision History  
Revision  
1.0  
Date  
6/15/2010  
8/8/2011  
11/21/2011  
12/20/2011  
08/13/2012  
Summary  
Initial release.  
1.1  
1.2  
2.0  
3.0  
Removed S/N options.  
Added ESD ratings.  
Changed to Pre-Production status. Changed tPU and tREC specs.  
Changed to Production status. Parameters tOD, tOH, tR, tF, tHH, tHZ & tLZ  
changed to “Guaranteed by Design”. Added PDIP package. Note: Packages  
marked * are under package vendor re-qualification.  
Ordering Information  
Part Number  
Features  
Operating  
Voltage  
Operating  
Temp.  
Package  
FM25V20-G  
Device ID  
Device ID  
Device ID  
Device ID  
2.0-3.6V  
2.0-3.6V  
2.0-3.6V  
2.0-3.6V  
-40C to +85C 8-pin “Green”/RoHS EIAJ  
-40C to +85C 8-pin “Green”/RoHS TDFN*  
-40C to +85C 8-pin “Green”/RoHS PDIP*  
-40C to +85C 8-pin “Green”/RoHS EIAJ,  
Tape & Reel  
FM25V20-DG  
FM25V20-PG  
FM25V20-GTR  
FM25V20-DGTR  
Device ID  
2.0-3.6V  
-40C to +85C 8-pin “Green”/RoHS TDFN,  
Tape & Reel  
Rev. 3.0  
August 2012  
Page 17 of 17  

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