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preliminary this is a product that has fixed target specifications but are subject ramtron international corporation to change pending characterization results. 1850 ramtron drive, colorado springs, co 80921 (800) 545-fram, (719) 481-7000 rev. 1.2 http://www.ramtron.com mar. 2011 page 1 of 11 fm1608b 64kb bytewide 5v f-ram memory features 64kbit ferroelectric nonvolatile ram ? organized as 8,192 x 8 bits ? high endurance 1 trillion (10 12 ) read/writes ? 38 year data retention ( @ +75 c) ? nodelay? writes ? advanced high-reliability ferroelectric process superior to bbsram modules ? no battery concerns ? monolithic reliability ? true surface mount solution, no rework steps ? superior for moisture, shock, and vibration ? resistant to negative voltage undershoots sram & eeprom compatible ? jedec 8kx8 sram & eeprom pinout ? 70 ns access time ? 130 ns cycle time low power operation ? 15 ma active current ? 25 a (typ.) standby current industry standard configuration ? industrial temperature -40 c to +85 c ? 28-pin ?green?/rohs soic package description the fm1608b is a 64-kilobit nonvolatile memory employing an advanced ferroelectric process. a ferroelectric random access memory or f-ram is nonvolatile but operates in other respects as a ram. it provides data retention for 38 years while eliminating the reliability concerns, functional disadvantages and system design complexities of battery-backed sram (bbsram). fast write timing and high write endurance make f-ram superior to other types of nonvolatile memory. in-system operation of the fm1608b is very similar to other ram devices. minimum read- and write- cycle times are equal. the f-ram memory, however, is nonvolatile due to its unique ferroelectric memory process. unlike bbsram, the fm1608b is a truly monolithic nonvolatile memory. it provides the same functional benefits of a fast write without the disadvantages associated with modules and batteries or hybrid memory solutions. these capabilities make the fm1608b ideal for nonvolatile memory applications requiring frequent or rapid writes in a bytewide environment. the availability of a true surface-mount package improves the manufacturability of new designs. device specifications are guaranteed over an industrial temperature range of -40c to +85c. pin configuration ordering information FM1608B-SG 28-pin ?green?/rohs soic nc a12 a7 a6 a5 a4 a3 a2 a1 a0 dq0 dq1 dq2 vss dq3 dq4 dq5 dq6 dq7 ce a10 oe a11 a9 a8 nc we vdd 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 2 of 11 address latch & decoder a0-a12 ce control logic we a0-a12 i/o latch bus driver oe 8,192 x 8 fram array dq0-7 figure 1. block diagram pin description pin name type description a(12:0) input address: the 13 address lines select one of 8,192 bytes in the f-ram array. the address value is latched on the falling edge of /ce. dq(7:0) i/o data: 8-bit bi-directional data bus for accessing the f-ram array. /ce input chip enable: /ce selects the device when low. asserting /ce low causes the address to be latched internally. address changes that occur after /ce goes low will be ignored until the next falling edge occurs. /oe input output enable: asserting /oe low causes the fm1608b to drive the data bus when valid data is available. deasserting /oe high causes the dq pins to be tri-stated. /we input write enable: asserting /we low causes the fm1608b to write the contents of the data bus to the address location latched by the falling edge of /ce. vdd supply supply voltage: 5v vss supply ground functional truth table /ce /we function h x standby/precharge x latch address (and begin write if /we=low) l h read l write note: the /oe pin controls only the dq output buffers.
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 3 of 11 overview the fm1608b is a bytewide f-ram memory. the memory array is logically organized as 8,192 x 8 and is accessed using an industry standard parallel interface. all data written to the part is immediately nonvolatile with no delay. functional operation of the f-ram memory is the same as sram type devices, except the fm1608b requires a falling edge of /ce to start each memory cycle. memory architecture users access 8,192 memory locations each with 8 data bits through a parallel interface. the complete 13-bit address specifies each of the 8,192 bytes uniquely. internally, the memory array is organized into 1024 rows of 8-bytes each. this row segmentation has no effect on operation, however the user may wish to group data into blocks by its endurance characteristics as explained on page 4. the cycle time is the same for read and write memory operations. this simplifies memory controller logic and timing circuits. likewise the access time is the same for read and write memory operations. when /ce is deasserted high, a precharge operation begins, and is required of every memory cycle. thus unlike sram, the access and cycle times are not equal. writes occur immediately at the end of the access with no delay. unlike an eeprom, it is not necessary to poll the device for a ready condition since writes occur at bus speed. it is the user?s responsibility to ensure that vdd remains within datasheet tolerances to prevent incorrect operation. also proper voltage level and timing relationships between vdd and /ce must be maintained during power-up and power-down events. see power cycle timing diagram on page 9. memory operation the fm1608b is designed to operate in a manner similar to other bytewide memory products. for users familiar with bbsram, the performance is comparable but the bytewide interface operates in a slightly different manner as described below. for users familiar with eeprom, the obvious differences result from the higher write performance of f-ram technology including nodelay writes and much higher write endurance. read operation a read operation begins on the falling edge of /ce. at this time, the address bits are latched and a memory cycle is initiated. once started, a full memory cycle must be completed internally even if /ce goes inactive. data becomes available on the bus after the access time has been satisfied. after the address has been latched, the address value may be changed upon satisfying the hold time parameter. unlike an sram, changing address values will have no effect on the memory operation after the address is latched. the fm1608b will drive the data bus when /oe is asserted low. if /oe is asserted after the memory access time has been satisfied, the data bus will be driven with valid data. if /oe is asserted prior to completion of the memory access, the data bus will not be driven until valid data is available. this feature minimizes supply current in the system by eliminating transients caused by invalid data being driven onto the bus. when /oe is inactive the data bus will remain tri-stated. write operation writes occur in the fm1608b in the same time interval as reads. the fm1608b supports both /ce- and /we-controlled write cycles. in all cases, the address is latched on the falling edge of /ce. in a /ce controlled write, the /we signal is asserted prior to beginning the memory cycle. that is, /we is low when /ce falls. in this case, the part begins the memory cycle as a write. the fm1608b will not drive the data bus regardless of the state of /oe. in a /we controlled write, the memory cycle begins on the falling edge of /ce. the /we signal falls after the falling edge of /ce. therefore, the memory cycle begins as a read. the data bus will be driven according to the state of /oe until /we falls. the timing of both /ce- and /we-controlled write cycles is shown in the electrical specifications. write access to the array begins asynchronously after the memory cycle is initiated. the write access terminates on the rising edge of /we or /ce, whichever is first. data set-up time, as shown in the electrical specifications, indicates the interval during which data cannot change prior to the end of the write access. unlike other truly nonvolatile memory technologies, there is no write delay with f-ram. since the read and write access times of the underlying memory are the same, the user experiences no delay through the bus. the entire memory operation occurs in a single bus cycle. therefore, any operation including read or write can occur immediately following a write. data polling, a technique used with eeproms to determine if a write is complete, is unnecessary.
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 4 of 11 precharge operation the precharge operation is an internal condition that prepares the memory for a new access. all memory cycles consist of a memory access and a precharge. the precharge is initiated by deasserting the /ce pin high. it must remain high for at least the minimum precharge time t pc . the user determines the beginning of this operation since a precharge will not begin until /ce rises. however, the device has a maximum /ce low time specification that must be satisfied. endurance internally, a f-ram operates with a read and restore mechanism. therefore, each read and write cycle involves a change of state. the memory architecture is based on an array of rows and columns. each read or write access causes an endurance cycle for an entire row. in the fm1608b, a row is 64 bits wide. every 8-byte boundary marks the beginning of a new row. endurance can be optimized by ensuring frequently accessed data is located in different rows. regardless, f-ram offers substantially higher write endurance than other nonvolatile memories. the rated endurance limit of 10 12 cycles will allow 3,000 accesses per second to the same row for over 10 years. f-ram design considerations when designing with f-ram for the first time, users of sram will recognize a few minor differences. first, bytewide f-ram memories latch each address on the falling edge of chip enable. this allows the address bus to change after starting the memory access. since every access latches the memory address on the falling edge of /ce, users cannot ground it as they might with sram. users who are modifying existing designs to use f- ram should examine the memory controller for timing compatibility of address and control pins. each memory access must be qualified with a low transition of /ce. in many cases, this is the only change required. an example of the signal relationships is shown in figure 2 below. also shown is a common sram signal relationship that will not work for the fm1608b. the reason for /ce to strobe for each address is two- fold: it latches the new address and creates the necessary precharge period while /ce is high. valid strobing of /ce fram signaling ce address a1 a2 data d1 d2 invalid strobing of /ce sram signaling ce address a1 a2 data d1 d2 figure 2. chip enable and memory address relationships
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 5 of 11 a second design consideration relates to the level of v dd during operation. battery-backed srams are forced to monitor v dd in order to switch to battery backup. they typically block user access below a certain v dd level in order to prevent loading the battery with current demand from an active sram. the user can be abruptly cut off from access to the nonvolatile memory in a power down situation with no warning or indication. f-ram memories do not need this system overhead. the memory will not block access at any v dd level that complies with the specified operating range. the user should take measures to prevent the processor from accessing memory when v dd is out-of- tolerance. the common design practice of holding a processor in reset during powerdown may be sufficient. it is recommended that chip enable is pulled high and allowed to track v dd during powerup and powerdown cycles. it is the user?s responsibility to ensure that chip enable is high to prevent accesses below v dd min. (4.5v). figure 3 shows a pullup resistor on /ce which will keep the pin high during power cycles assuming the mcu/mpu pin tri-states during the reset condition. the pullup resistor value should be chosen to ensure the /ce pin tracks v dd yet a high enough value that the current drawn when /ce is low is not an issue. figure 3. use of pullup resistor on /ce ce we oe a(12:0) dq fm1608b v dd mcu/ mpu r
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 6 of 11 electrical specifications absolute maximum ratings symbol description ratings v dd power supply voltage with respect to v ss -1.0v to +7.0v v in voltage on any pin with respect to v ss -1.0v to +7.0v and v in < v dd +1.0v t stg storage temperature -55 c to + 125 c t lead lead temperature (soldering, 10 seconds) 260 c v esd 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) 4kv 1.25kv 300v package moisture sensitivity level msl-2 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 reliabilit y. dc operating conditions (t a = -40 c to + 85 c, v dd = 4.5v to 5.5v unless otherwise specified) symbol parameter min typ max units notes v dd power supply 4.5 5.0 5.5 v i dd v dd supply current - 15 ma 1 i sb1 standby current (ttl) - 1.8 ma 2 i sb2 standby current (cmos ) 25 50 a 3 i li input leakage current - 1 a 4 i lo output leakage current - 1 a 4 v ih input high voltage 2.0 v dd +0.3 v v il input low voltage -0.3 0.8 v v oh1 output high voltage ( i oh = -2 ma) 2.4 v v oh2 output high voltage ( i oh = -100 a) v dd -0.2 v v ol1 output low voltage ( i ol = 4.2 ma) 0.4 v v ol2 output low voltage ( i ol = 150 a) 0.2 v notes 1. v dd = 5.5v, /ce cycling at minimum cycle time. all inputs at cmos levels, all outputs unloaded. 2. v dd = 5.5v, /ce at v ih , all other pins at ttl levels. 3. v dd = 5.5v, /ce at v ih , all other pins at cmos levels (0.2v or v dd -0.2v). 4. v in , v out between v dd and v ss .
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 7 of 11 read cycle ac parameters (t a = -40 c to + 85 c, v dd = 4.5v to 5.5v unless otherwise specified) symbol parameter min max units notes t ce chip enable access time (to data valid) 70 ns t c a chip enable active time 70 ns t rc read cycle time 130 ns t pc precharge time 60 ns t as address setup time 0 ns t ah address hold time 15 ns t oe output enable access time 12 ns t hz chip enable to output high-z 15 ns 1 t ohz output enable to output high-z 15 ns 1 write cycle ac parameters (t a = -40 c to + 85 c, v dd = 4.5v to 5.5v unless otherwise specified) symbol parameter min max units notes t c a chip enable active time 70 ns t cw chip enable to write high 70 ns t wc write cycle time 130 ns t pc precharge time 60 ns t as address setup time 0 ns t ah address hold time 15 ns t wp write enable pulse width 40 ns t ds data setup 30 ns t dh data hold 0 ns t wz write enable low to output high z 15 ns 1 t wx write enable high to output driven 10 ns 1 t hz chip enable to output high-z 15 ns 1 t ws write enable setup 0 ns 2 t wh write enable hold 0 ns 2 notes 1 this parameter is periodically sampled and not 100% tested. 2 the relationship between /ce and /we determines if a /ce- or /we-controlled write occurs. there is no timing specification associated with this relationship. data retention symbol parameter min max units notes t dr @ +85oc 10 - years @ +80oc 19 - years @ +75oc 38 - years
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 8 of 11 capacitance (t a = 25 c, f=1.0 mhz, v dd = 5v) symbol parameter min max units notes c i/o input/output capacitance (dq) - 8 pf c in input capacitance - 6 pf ac test conditions input pulse levels 0 to 3v input rise and fall times 10 ns input and output timing levels 1.5v read cycle timing ce a(12:0) oe dq(7:0) t as t ah t ce t oe t ca t rc t pc t ohz t hz write cycle timing - /ce controlled timing ce a(12:0) we dq(7:0) t as t ah t ca t wc t pc oe t ws t ds t dh t wh equivalent ac load circuit
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 9 of 11 write cycle timing - /we controlled timing ce a(12:0) we dq(7:0) out t as t ah t ca t wc t pc oe t ws t wh dq(7:0) in t ds t wp t wz t wx t dh t c w power cycle timing power cycle timing (t a = -40 c to + 85 c, v dd = 4.5v to 5.5v unless otherwise specified) symbol parameter min max units notes t pu v dd (min) to first access start 10 - ms t pd last access complete to v dd (min) 0 - s t vr v dd rise time 30 - s/v 1 t vf v dd fall time 100 - s/v 1 notes 1 slope measured at any point on v dd waveform. v ih (min) t pd t pu v dd ce v il (max) v dd (min) t pc v dd (min) v ih (min) v ih (min) v ih (min) t pd t pd t pu t pu v dd ce v il (max) v il (max) v dd (min) v dd (min) t pc t pc v dd (min) v dd (min) v ih (min) v ih (min)
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 10 of 11 28-pin soic (jedec ms-013 variation ae) all dimensions in millimeters pin 1 7.50 0.10 10.30 0.30 17.90 0.20 0.10 0.30 2.35 2.65 0.33 0.51 1.27 typ 0.10 0.25 0.75 45 0.40 1.27 0.23 0.32 0? - 8? soic package marking scheme legend: xxxxxx= part number, p= package type (-sg) r=rev code, yy=year, ww=work week, llllll= lot code example: fm1608b, 70ns speed, ?green?/rohs soic package, a die rev., year 2010, work week 37, lot code 00002g ramtron FM1608B-SG a103700002g ramtron xxxxxxx-p ryywwlllllll
fm1608b ? 64kb bytewide 5v f-ram rev. 1.2 mar. 2011 page 11 of 11 revision history revision date summary 1.0 11/22/2010 initial release 1.1 12/20/2010 updated msl rating. 1.2 3/14/2011 changed t pu and t vf spec limits.

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