FM25L04B

Preliminary FM25L04B 4Kb Serial 3V F-RAM Memory Features 4K bit Ferroelectric Nonvolatile RAM • Organized as 512 x 8 bits • High Endurance 100 Trillion (1014) Read/Writes • 38 Year Data Retention (@ +75ºC) • NoDelay™ Writes • Advanced High-Reliability Ferroelectric Process Very Fast Serial Peripheral Interface - SPI • Up to 20 MHz Frequency • Direct Hardware Replacement for EEPROM • SPI Mode 0 & 3 (CPOL, CPHA=0,0 & 1,1) Sophisticated Write Protection Scheme • Hardware Protection • Software Protection Low Power Consumption • Low Voltage Operation 2.7-3.6V • 200 µA Active Current (1 MHz) • 3 µA (typ.) Standby Current Industry Standard Configuration • Industrial Temperature -40°C to +85°C • 8-pin “Green”/RoHS SOIC and TDFN Packages Description The FM25L04B is a 4-kilobit 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 38 years while eliminating the complexities, overhead, and system level reliability problems caused by EEPROM and other nonvolatile memories. The FM25L04B performs write operations at bus speed. No write delays are incurred. Data is written to the memory array immediately after each byte has been transferred to the device. The next bus cycle may commence without the need for data polling. The FM25L04B is capable of supporting 1014 read/write cycles, or a million times more write cycles than EEPROM. These capabilities make the FM25L04B 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 industrial controls where the long write time of EEPROM can cause data loss. The FM25L04B provides substantial benefits to users of serial EEPROM as a hardware drop-in replacement. The FM25L04B uses the high-speed SPI bus, which enhances the high-speed write capability of F-RAM technology. Device specifications are guaranteed over an industrial temperature range of -40°C to +85°C. Pin Configuration CS SO WP VSS 1 2 3 4 8 7 6 5 VDD HOLD SCK SI Top View /CS SO /WP VSS 1 2 3 4 8 7 6 5 VDD /HOLD SCK SI Pin Name /CS /WP /HOLD SCK SI SO VDD VSS Function Chip Select Write Protect Hold Serial Clock Serial Data Input Serial Data Output Supply Voltage Ground Ordering Information FM25L04B-G FM25L04B-GTR FM25L04B-DG FM25L04B-DGTR “Green”/RoHS 8-pin SOIC “Green”/RoHS 8-pin SOIC, Tape & Reel “Green”/RoHS 8-pin TDFN “Green”/RoHS 8-pin TDFN, Tape & Reel This is a product that has fixed target specifications but are subject to change pending characterization results. Ramtron International Corporation 1850 Ramtron Drive, Colorado Springs, CO 80921 (800) 545-F-RAM, (719) 481-7000 www.ramtron.com Rev. 1.3 Feb. 2011 Page 1 of 14 FM25L04B - 4Kb 3V SPI F-RAM WP CS HOLD SCK Instruction Decode Clock Generator Control Logic Write Protect 64 x 64 FRAM Array Instruction Register Address Register Counter SI 9 8 Data I/O Register 3 Nonvolatile Status Register SO Figure 1. Block Diagram Pin Descriptions Pin Name /CS I/O Input Description 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 SCK signal. A falling edge on /CS must occur prior to every op-code. 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 20 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 SCK or /CS. All transitions on /HOLD must occur while SCK is low. Write Protect: This active low pin prevents write operations to the memory array or the status register. A complete explanation of write protection is provided below. 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. * SI may be connected to SO for a single pin data interface. 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. * SO may be connected to SI for a single pin data interface. Power Supply (2.7V to 3.6V) Ground SCK Input /HOLD Input /WP SI Input Input SO Output VDD VSS Supply Supply Rev. 1.3 Feb. 2011 Page 2 of 14 FM25L04B - 4Kb 3V SPI F-RAM Overview The FM25L04B is a serial F-RAM memory. The memory array is logically organized as 512 x 8 and is accessed using an industry standard Serial Peripheral Interface or SPI bus. Functional operation of the FRAM is similar to serial EEPROMs. The major difference between the FM25L04B and a serial EEPROM with the same pinout is the F-RAM’s superior write performance and power consumption. high performance serial communication to a host 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 FM25L04B operates in SPI Mode 0 and 3. 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 FM25L04B devices with a microcontroller that has a dedicated SPI port, as Figure 2 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 FM25L04B device. 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 pin. Figure 3 shows a configuration that uses only three pins. Protocol 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 FM25L04B will begin monitoring the clock and data lines. The relationship between the falling edge of /CS, 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 FM25L04B supports Modes 0 and 3. Figure 4 shows the required signal relationships for Modes 0 and 3. For both modes, data is clocked into the FM25L04B on the rising edge of SCK and data is expected on the first rising edge after /CS goes active. If the clock begins from a high state, it will fall prior to beginning data transfer in order to create the first rising edge. The SPI protocol is controlled by op-codes. These op-codes specify the commands to the device. After /CS 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. Note that the WREN and WRDI op-codes are commands with no subsequent data transfer. Important: The /CS must go inactive (high) 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. Memory Architecture When accessing the FM25L04B, the user addresses 512 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 an address. The upper address bit is included in the opcode. The complete address of 9-bits specifies each byte address uniquely. Most functions of the FM25L04B 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 an EEPROM, 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. Users expect several obvious system benefits from the FM25L04B due to its fast write cycle and high endurance as compared with EEPROM. 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 an EEPROM since it is completed quickly. By contrast, an EEPROM requiring milliseconds to write is vulnerable to noise during much of the cycle. Note that the FM25L04B contains no power management circuits other than a simple internal power-on reset. 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 FM25L04B employs a Serial Peripheral Interface (SPI) bus. It is specified to operate at speeds up to 20 MHz. This high-speed serial bus provides Rev. 1.3 Feb. 2011 Page 3 of 14 FM25L04B - 4Kb 3V SPI F-RAM SCK MOSI MISO SO SPI Microcontroller SI SCK SO SI SCK FM25L04B CS SS1 SS2 HOLD1 HOLD2 HOLD FM25L04B CS HOLD MOSI : Master Out Slave In MISO : Master In Slave Out SS : Slave Select Figure 2. System Configuration with SPI port Figure 3. System Configuration without SPI port SPI Mode 0: CPOL=0, CPHA=0 7 6 5 4 3 2 1 0 SPI Mode 3: CPOL=1, CPHA=1 7 6 5 4 3 2 1 0 Figure 4. SPI Modes 0 & 3 Rev. 1.3 Feb. 2011 Page 4 of 14 FM25L04B - 4Kb 3V SPI F-RAM Data Transfer All data transfers to and from the FM25L04B occur in 8-bit groups. They are synchronized to the clock signal (SCK), and they transfer most significant bit (MSB) first. Serial inputs are registered on the rising edge of SCK. Outputs are driven from the falling edge of SCK. Command Structure There are six commands called op-codes that can be issued by the bus master to the FM25L04B. 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. Table 1. Op-code Commands Name Description Set Write Enable Latch WREN Write Disable WRDI Read Status Register RDSR Write Status Register WRSR Read Memory Data READ WRITE Write Memory Data WREN - Set Write Enable Latch The FM25L04B 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 and writing the memory. 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. Completing any write operation will automatically clear the write-enable latch and prevent further writes without another WREN command. Figure 5 below illustrates the WREN command bus configuration. 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. Op-code 0000 0000 0000 0000 0000 0000 0110b 0100b 0101b 0001b A011b A010b CS 0 SCK 1 2 3 4 5 6 7 SI SO 0 0 0 0 Hi-Z 0 1 1 0 Figure 5. WREN Bus Configuration CS 0 SCK 1 2 3 4 5 6 7 SI SO 0 0 0 0 Hi-Z 0 1 0 0 Figure 6. WRDI Bus Configuration Rev. 1.3 Feb. 2011 Page 5 of 14 FM25L04B - 4Kb 3V SPI F-RAM 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 opcode, the FM25L04B will return one byte with the contents of the Status Register. The Status Register is described in detail in a later section. 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 /WP pin must be high or inactive. Prior to sending the WRSR command, the user must send a WREN command to enable writes. Note that executing a WRSR command is a write operation and therefore clears the Write Enable Latch. Figure 7. RDSR Bus Configuration Figure 8. WRSR Bus Configuration (WREN not shown) Status Register & Write Protection The write protection features of the FM25L04B are multi-tiered. Taking the /WP pin to a logic low state is the hardware write protect function. All write operations are blocked when /WP is low. To write the memory with /WP high, a WREN op-code must first be issued. Assuming that writes are enabled using WREN and by /WP, 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 /WP pin. The Status Register is organized as follows. Table 2. Status Register Bit Name 7 0 6 0 5 0 4 0 3 BP1 2 BP0 1 WEL 0 0 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 the following table. Table 3. Block Memory Write Protection BP1 BP0 Protected Address Range 0 0 None 0 1 180h to 1FFh (upper ¼) 1 0 100h to 1FFh (upper ½) 1 1 000h to 1FFh (all) The BP1 and BP0 bits allow software to selectively write-protect the array. These settings are only used when the /WP pin is inactive and the WREN command has been issued. The following table summarizes the write protection conditions. Bits 0 and 7-4 are fixed at 0 and cannot be modified. Note that bit 0 (“Ready” in EEPROMs) is unnecessary as the F-RAM writes in real-time and is never busy. The BP1 and BP0 control write protection features. They are nonvolatile (shaded yellow). The WEL flag indicates the state of the Rev. 1.3 Feb. 2011 Page 6 of 14 FM25L04B - 4Kb 3V SPI F-RAM Table 4. Write Protection WEL /WP Protected Blocks 0 X Protected 1 0 Protected 1 1 Protected Unprotected Blocks Protected Protected Unprotected Status Register Protected Protected Unprotected 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 SPI-bus EEPROMs, the FM25L04B 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 array begin with a WREN op-code. The next op-code is the WRITE instruction. This op-code must include the address MSB. It is followed by a single byte address value. In total, the 9-bits specify the address of the first 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 1FFh is reached, the counter will roll over to 000h. Data is written MSB first. A write operation is shown in Figure 9. Unlike EEPROMs, 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 /CS terminates a WRITE op-code operation. Asserting /WP active in the middle of a write operation will have no effect until the byte being written has completed. Read Operation After the falling edge of /CS, the bus master can issue a READ op-code. This op-code must include the address MSB. It is followed by a single byte address value. In total, the 9-bits specify the address of the first byte of the read operation. After the op-code and address are complete, the SI line is ignored. The bus master issues 8 clocks, with 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 1FFh is reached, the counter will roll over to 000h. Data is read MSB first. The rising edge of /CS terminates a READ op-code operation. A read operation is shown in Figure 10. Hold 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 high while SCK is low will resume an operation. The transitions of /HOLD must occur while SCK is low, but the SCK and /CS pins can toggle during a hold state. Figure 9. Memory Write (WREN not shown) Figure 10. Memory Read Rev. 1.3 Feb. 2011 Page 7 of 14 FM25L04B - 4Kb 3V SPI F-RAM 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 20MHz clock rate. Endurance The FM25L04B devices are capable of being accessed at least 1014 times, reads or writes. An FRAM 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 A8-A3 and column addresses by A2-A0. See Block Diagram (pg 2) which shows the array as 64 rows of Table 5. Time to Reach Endurance Limit for Repeating 64-byte Loop SCK Freq Endurance Endurance Years to Reach (MHz) Cycles/sec. Cycles/year Limit 20 37,310 1.18 x 1012 85.1 10 18,660 5.88 x 1011 170.2 5 9,330 2.94 x 1011 340.3 Rev. 1.3 Feb. 2011 Page 8 of 14 FM25L04B - 4Kb 3V SPI F-RAM Electrical Specifications Absolute Maximum Ratings Symbol Description VDD Power Supply Voltage with respect to VSS VIN Voltage on any pin with respect to VSS TSTG TLEAD VESD Storage Temperature Lead Temperature (Soldering, 10 seconds) Electrostatic Discharge Voltage - Human Body Model (AEC-Q100-002 Rev. E) - Charged Device Model (AEC-Q100-011 Rev. B) - Machine Model (AEC-Q100-003 Rev. E) Package Moisture Sensitivity Level Ratings -1.0V to +5.0V -1.0V to +5.0V and VIN < VDD+1.0V -55°C to + 125°C 260° C 4kV 1.25kV 300V 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 = -40° C to + 85° C, VDD = 2.7V to 3.6V unless otherwise specified) Symbol Parameter Min Typ Max Units VDD Power Supply Voltage 2.7 3.3 3.6 V IDD VDD Supply Current mA 0.2 @ SCK = 1.0 MHz mA 3.0 @ SCK = 20.0 MHz ISB Standby Current 3 6 µA ILI Input Leakage Current ±1 µA ILO Output Leakage Current ±1 µA VIH Input High Voltage 0.7 VDD VDD + 0.3 V VIL Input Low Voltage -0.3 0.3 VDD V VDD – 0.8 VOH Output High Voltage V @ IOH = -2 mA VOL Output Low Voltage 0.4 V @ IOL = 2 mA VHYS Input Hysteresis 0.05 VDD V Notes 1. SCK toggling between VDD-0.3V and VSS, other inputs VSS or VDD-0.3V. 2. SCK = SI = /CS=VDD. All inputs VSS or VDD. 3. VSS ≤ VIN ≤ VDD and VSS ≤ VOUT ≤ VDD. 4. This parameter is characterized but not 100% tested. Applies only to /CS and SCK pins. Notes 1 2 3 3 4 Rev. 1.3 Feb. 2011 Page 9 of 14 FM25L04B - 4Kb 3V SPI F-RAM AC Parameters (TA = -40° C to + 85° C, VDD = 2.7V to 3.6V, CL = 30pF, unless otherwise specified) Symbol Parameter Min Max Units Notes fCK SCK Clock Frequency 0 20 MHz tCH Clock High Time 22 ns 1 tCL Clock Low Time 22 ns 1 tCSU Chip Select Setup 10 ns tCSH Chip Select Hold 10 ns tOD Output Disable Time 20 ns 2 tODV Output Data Valid Time 20 ns tOH Output Hold Time 0 ns tD Deselect Time 60 ns tR Data In Rise Time 50 ns 2,3 tF Data In Fall Time 50 ns 2,3 tSU Data Setup Time 5 ns tH Data Hold Time 5 ns tHS /HOLD Setup Time 10 ns tHH /HOLD Hold Time 10 ns tHZ /HOLD Low to Hi-Z 20 ns 2 tLZ /HOLD High to Data Active 20 ns 2 Notes 1. 2. 3. 4. tCH + tCL = 1/fCK. For Clock High Time tCH ≤ 35 ns, the parameter tODV is extended such that tCH + tODV ≤ 65 ns. This parameter is characterized but not 100% tested. Rise and fall times measured between 10% and 90% of waveform. Capacitance (TA = 25° C, f=1.0 MHz, VDD = 3.3V) Symbol Parameter CO Output Capacitance (SO) CI Input Capacitance Notes 1. This parameter is characterized but not 100% tested. 2. Slope measured at any point on VDD waveform. AC Test Conditions Input Pulse Levels Input rise and fall times Input and output timing levels Output Load Capacitance Min - Max 8 6 Units pF pF Notes 1 1 10% and 90% of VDD 5 ns 0.5 VDD 30 pF Data Retention Symbol Parameter TDR @ +85ºC @ +80ºC @ +75ºC Min 10 19 38 Max - Units Years Years Years Notes Rev. 1.3 Feb. 2011 Page 10 of 14 FM25L04B - 4Kb 3V SPI F-RAM Serial Data Bus Timing tD CS tCSU SCK tSU SI tODV SO tOH tOD tH 1/tCK tF tR tCL tCH tCSH /Hold Timing tHS CS tHH SCK tHS HOLD tHH SO tHZ tLZ Power Cycle Timing Power Cycle Timing (TA = -40° C to + 85° C, VDD = 2.7V to 3.6V unless otherwise specified) Symbol Parameter Min Max Units tPU VDD(min) to First Access Start 10 ms tPD Last Access Complete to VDD(min) 0 µs tVR VDD Rise Time 30 µs/V tVF VDD Fall Time 100 µs/V Notes 1. Slope measured at any point on VDD waveform. Notes 1 1 Rev. 1.3 Feb. 2011 Page 11 of 14 FM25L04B - 4Kb 3V SPI F-RAM Mechanical Drawing 8-pin SOIC (JEDEC Standard MS-012 variation AA) Recommended PCB Footprint 7.70 3.90 ±0.10 6.00 ±0.20 2.00 3.70 Pin 1 1.27 0.65 4.90 ±0.10 1.35 1.75 0.25 0.50 45 ° 0.19 0.25 1.27 0.33 0.51 0.10 0.25 0.10 mm 0°- 8° 0.40 1.27 Refer to JEDEC MS-012 for complete dimensions and notes. All dimensions in millimeters. SOIC Package Marking Scheme Legend: XXXXXX= part number, P= package type (G=SOIC) R=rev code, LLLLLLL= lot code RIC=Ramtron Int’l Corp, YY=year, WW=work week Example: FM25L04B, “Green” SOIC package, Year 2010, Work Week 47 FM25L04B-G A00002G1 RIC1047 XXXXXXX-P RLLLLLLL RICYYWW Rev. 1.3 Feb. 2011 Page 12 of 14 FM25L04B - 4Kb 3V SPI F-RAM 8-pin TDFN (4.0mm x 4.5mm body, 0.95mm pitch) 4.50 ±0.1 Exposed metal pad should be left floating. 4.00 ±0.1 3.60 ±0.10 2.60 ±0.10 Pin 1 ID Pin 1 2.85 REF 0.75 ±0.05 0.0 - 0.05 0.30 ±0.1 0.20 REF. 0.95 0.40 ±0.05 Recommended PCB Footprint 4.30 0.60 0.45 0.95 Note: All dimensions in millimeters. The exposed pad should be left floating. TDFN Package Marking Scheme for Body Size 4.0mm x 4.5mm Legend: R=Ramtron, G=”green” TDFN package, XXXX=base part number LLLL= lot code YY=year, WW=work week Example: “Green”/RoHS TDFN package, FM25L04B, Lot 0003, Year 2011, Work Week 07 R5L04B 0003 1107 RGXXXX LLLL YYWW Rev. 1.3 Feb. 2011 Page 13 of 14 FM25L04B - 4Kb 3V SPI F-RAM Revision History Revision 1.0 1.1 1.2 1.3 Date 11/10/2010 12/15/2010 1/31/2011 2/15/2011 Summary Initial Release Fixed endurance section on pg 8. Added ESD ratings. Updated DFN package marking. Changed tPU and tVF spec limits. Rev. 1.3 Feb. 2011 Page 14 of 14