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this p roduct conform s to specifications per the terms of the ramtron ramtron international corporation standard warranty. the product has completed ramtrons internal 1850 ramtron drive, colorado springs, co 80921 qualification testing and has reached production status . (800) 545 - fram, (7 19) 481 - 7000 rev. 3.0 www.ramtron.com jan. 2012 page 1 of 12 fm 24c16b 16kb serial 5v f - ram memory features 16k bit ferroelectric nonvolatile ram ? organized as 2,048 x 8 bits ? high endurance (10 12 ) read/write cycles ? 38 year data retention ? nodelay? writes ? advanced high - reliability ferroelec tric process fast two - wire serial interface ? up to 1mhz maximum bus frequency ? direct hardware replacement for eeprom ? supports legacy timing for 100 khz & 400 khz low power operation ? 5v operation ? 1 0 0 ? a active current (100 khz) ? 4 ? a (typ.) standby curr ent industry standard configuration ? industrial temperature - 40 ? c to +85 ? c ? 8 - pin green /rohs soic ( - g) description the fm 24c16b is a 16 - kilobit nonvolatile memory employing an advanced ferroelectric process. a ferroelectric random access memory or fram 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. t he fm 24c16b p erforms write operations at bus speed. no write delays are incurred. data is written to the memory array in the cycle after it has been successfully transferred to the device. the next bus cycle may commence immediately without the need for data polling. t he fm 24c16b is capable of supporting 10 12 read/write cycles, or a million times more write cycles than eeprom. these capabilities make the fm 24c16b ideal for nonvolatile memory applications requiring frequent or rapid writes. examples range from data coll ection 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 combination of features allows the system to write data more frequently, with less system overhead. the fm 24c16b provides substantial benefits to users of serial eeprom, and these benefits are available as a hardware drop - in replacement. the fm 24c16b is available in an industry standard 8 - pin soic package and uses a familiar two - wire protocol. the specifica tions are guaranteed over the ind ustrial temperature range from - 40c to +85c. pin configuration pin names function sda serial data/address scl serial clock wp write protect vss ground vdd supply voltage ordering information fm24c16b - g g reen/rohs 8 green/rohs 8 nc nc nc vss vdd wp scl sda 1 2 3 4 8 7 6 5
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 2 of 12 figure 1. block diagram pin description pin name type pin description sda i/o serial data address: this is a bi - directional data pin for the tw o - wire interface. it employs an open - drain output and is intended to be wire - ord with other devices on the two - wire bus. the input buffer incorporates a schmitt trigger for noise immunity and the output driver includes slope control for falling edges. a p ull - up resistor is required. scl input serial clock: the serial clock input for the two - wire interface. data is clocked - out on the falling edge and clocked - in on the rising edge. wp input write protect: when wp is high, the entire array is write - protecte d. when wp is low, all addresses may be written. this pin is internally pulled down. vdd supply supply voltage (5v) vss supply ground nc - no connect address latch ` 256 x 64 fram array data latch 8 sda counter serial to parallel converter control logic scl wp
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 3 of 12 overview the fm 24c16b is a serial fram memory. the memory array is logically organized as a 2,048 x 8 memory array and is accessed using an industry standard two - wire interface. functional operation of the fram is similar to serial eeproms. the major difference between the fm 24c16b and a serial eeprom with the same pinout relates to its superior write pe rformance. memory architecture when accessing the fm 24c16b , the user addresses 2,048 locations each with 8 data bits. these data bits are shifted serially. the 2,048 addresses are accessed using the two - wire protocol, which includes a slave address (to di stinguish from other non - memory devices), a row address, and a segment address. the row address consists of 8 - bits that specify one of 256 rows. the 3 - bit segment address specifies one of 8 segments within each row. the complete 11 - bit address specifies ea ch byte uniquely. most functions of the fm 24c16b either are controlled by the two - wire interface or handled automatically by on - board circuitry. the memory is read or written at the speed of the two - wire bus. unlike an eeprom, it is not necessary to poll the device for a ready condition since writes occur at bus speed. that is, by the time a new bus transaction can be shifted into the part, a write operation is complete. this is explained in more detail in the interface section below. note that the fm 24 c16b contains no power management circuits other than a simple internal power - on reset. it is the users responsibility to ensure that vdd is within data sheet tolerances to prevent incorrect operation. two - wire interface the fm 24c16b employs a bi - direct ional two - wire bus protocol using few pins and little board space. figure 2 illustrates a typical system configuration using the fm 24c16b in a microcontroller - based system. the industry standard two - wire bus is familiar to many users but is described in th is section. by convention, any device that is sending data onto the bus is the transmitter while the target device for this data is the receiver. the device that is controlling the bus is the master. the master is responsible for generating the clock sign al for all operations. any device on the bus that is being controlled is a slave. the fm 24c16b is always a slave device. the bus protocol is controlled by transition states in the sda and scl signals. there are four conditions including start, stop, data bit, and acknowledge. figure 3 illustrates the signal conditions that define the four states. detailed timing diagrams are shown in the electrical s pecifications section . figure 2. typical system configuration microcontroller sda scl fm 24 c 16 b sda scl other slave device vdd rmin = 1 . 8 k ohm rmax = tr / cbus
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 4 of 12 figure 3. data transfer protocol stop condition a stop condition is indicated when the bus master drives sda from low to high while the scl signal is high. all operations using the fm 24c16b must end with a stop condition. if an op eration is pending when a stop is asserted, the operation will be aborted. the master must have control of sda (not a memory read) in order to assert a stop condition. start condition a start condition is indicated when the bus master drives sda from high to low while the scl signal is high. all read and write transactions begin with a start condition. an operation in progress can be aborted by asserting a start condition at any time. aborting an operation using the start condition will prepare the fm 24c16 b for a new operation. if during operation the power supply drops below the specified vdd minimum, the system should issue a start condition prior to performing another operation. data/address transfer all data transfers (including addresses) take place while the scl signal is high. except under the two conditions described above, the sda signal should not change while scl is high. for system design considerations, keeping scl in a low state while idle improves robustness. acknowledge the acknowledge tak es place after the 8 th data bit has been transferred in any transaction. during this state, the transmitter should release the sda bus to allow the receiver to drive it. the receiver drives the sda signal low to acknowledge receipt of the byte. if the rece iver does not drive sda low, the condition is a no - acknowledge and the operation is aborted. the receiver would fail to acknowledge for two distinct reasons. first is that a byte transfer fails. in this case, the no - acknowledge ends the current operation so that the part can be addressed again. this allows the last byte to be recovered in the event of a communication error. second and most common, the receiver does not acknowledge to deliberately end an operation. for example, during a read operation, t he fm 24c16b will continue to place data onto the bus as long as the receiver sends acknowledges (and clocks). when a read operation is complete and no more data is needed, the receiver must not acknowledge the last byte. if the receiver acknowledges the la st byte, this will cause the fm 24c16b to attempt to drive the bus on the next clock while the master is sending a new command such as a stop. slave address the first byte that the fm 24c16b expects after a start condition is the slave address. as shown in figure 4, the slave address contains the device type, the page of memory to be accessed, and a bit that specifies if the transaction is a read or a write. bits 7 - 4 are the device type and should be set to 1010b for the fm 24c16b . the device type allows ot her types of functions to reside on the 2 - wire bus within an identical address range. bits 3 - 1 are the page select. they specify the 256 - byte block of memory that is targeted for the current operation. bit 0 is the read/write bit. a 0 indicates a write ope ration. stop (master) start (master) 7 data bits (transmitter) 6 0 data bit (transmitter) acknowledge (receiver) scl sda
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 5 of 12 figure 4. slave address word address after the fm 24c16b (as receiver) acknowledges the slave id, the master will place the word address on the bus for a write operation. the word address is the lower 8 - bits of the a ddress to be combined with the 3 - bits of the page select to specify the exact byte to be written. the complete 11 - bit address is latched internally. no word address occurs for a read operation, though the 3 - bit page select is latched internally. reads al ways use the lower 8 - bits that are held internally in the address latch. that is, reads always begin at the address following the previous access. a random read address can be loaded by doing a write operation as explained below. after transmission of ea ch data byte, just prior to the acknowledge, the fm 24c16b increments the internal address latch. this allows the next sequential byte to be accessed with no additional addressing. after the last address (7ffh) is reached, the address latch will roll over t o 000h. there is no limit on the number of bytes that can be accessed with a single read or write operation. data transfer after all address information has been transmitted, data transfer between the bus master and the fm 24c16b can begin. for a read oper ation the device will place 8 data bits on the bus then wait for an acknowledge. if the acknowledge occurs, the next sequential byte will be transferred. if the acknowledge is not sent, the read operation is concluded. for a write operation, the fm 24c16b w ill accept 8 data bits from the master then send an acknowledge. all data transfer occurs msb (most significant bit) first. memory operation the fm 24c16b is designed to operate in a manner very similar to other 2 - wire interface memory products. the major differences result from the higher performance write capability of fram technology. these improvements result in some differences between the fm 24c16b and a similar configuration eeprom during writes. the complete operation for both writes and reads is ex plained below. write operation all writes begin with a slave id then a word address as previously mentioned. the bus master indicates a write operation by setting the lsb of the slave address to a 0. after addressing, the bus master sends each byte of dat a to the memory and the memory generates an acknowledge condition. any number of sequential bytes may be written. if the end of the address range is reached internally, the address counter will wrap from 7ffh to 000h. unlike other nonvolatile memory tech nologies, there is no write delay with fram. the entire memory cycle occurs in less time than a single bus clock. therefore, any operation including read or write can occur immediately following a write. acknowledge polling, a technique used with eeproms to determine if a write is complete is unnecessary and will always return a ready condition. an actual memory array write occurs after the 8 th data bit is transferred. it will be complete before the acknowledge is sent. therefore, if the user desires t o abort a write without altering the memory contents, this should be done using start or stop condition prior to the 8 th data bit. the fm 24c16b needs no page buffering. the memory array can be write protected using the wp pin. pulling wp high will disabl e writes to the entire array . the fm 24c16b will not acknowledge data bytes that are written to protected addresses. in addition, the address counter will not increment if writes are attempted to these addresses. pulling wp low (v ss ) will deactivate this feature . figure 5 and 6 below illustrate both a sing le - byte and multiple - byte write cases . 1 0 1 0 a2 a1 a0 r/w slave id page select
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 6 of 12 figure 5. single byte write figure 6. multiple byte write read op eration there are two types of read operations. they are current address read and selective address read. in a current address read, the fm 24c16b uses the internal address latch to supply the lower 8 address bits. in a selective read, the user performs a p rocedure to set these lower address bits to a specific value. current address & sequential read as mentioned above the fm 24c16b uses an internal latch to supply the lower 8 address bits for a read operation. a current address read uses the existing value in the address latch as a starting place for the read operation. this is the address immediately following that of the last operation. to perform a current address read, the bus master supplies a slave address with the lsb set to 1. this indicates that a read operation is requested. the 3 page select bits in the slave id specify the block of memory that is used for the read operation. on the next clock, the fm 24c16b will begin shifting out data from the current address. the current address is the 3 bits from the slave id combined with the 8 bits that were in the internal address latch. beginning with the current address, the bus master can read any number of bytes. thus, a sequential read is simply a current address read with multiple byte transfers. af ter each byte, the internal address counter will be incremented. each time the bus master acknowledges a byte this indicates that the fm 24c16b should read out the next sequential byte. there are four ways to properly terminate a read operation. failing to properly terminate the read will most likely create a bus contention as the fm 24c16b attempts to read out additional data onto the bus. the four valid methods are as follows. 1. the bus master issues a no - acknowledge in the 9 th clock cycle and a stop in th e 10 th clock cycle. this is illustrated in the diagrams below. this is the preferred method. 2. the bus master issues a no - acknowledge in the 9 th clock cycle and a start in the 10 th . 3. the bus master issues a stop in the 9 th clock cycle. bus contention may re sult. 4. the bus master issues a start in the 9 th clock cycle. bus contention may result. if the internal address reaches 7ffh it will wrap around to 000h on the next read cycle. figures 7 and 8 show the proper operation for current address reads. selectiv e (random) read a simple technique allows a user to select a random address location as the starting point for a read operation. it uses the first two bytes of a write operation to set the internal address byte followed by subsequent read operations. to perform a selective read, the bus master sends out the slave address with the lsb set to 0. this specifies a write operation. according to the write protocol, the bus master then sends the word address byte that is loaded into the internal address latch. a fter the fm 24c16b acknowledges the word address, the bus master issues a start condition. this simultaneously aborts the write operation and allows the read command to be issued with the slave address set to 1. the operation is now a current address read. this operation is illustrated in figure 9. s a slave address 0 word address a data byte a p by master by fm 24 c 16 b start address & data stop acknowledge s a slave address 0 word address a data byte a p by master by fm 24 c 16 b start address & data stop acknowledge data byte a
ramtron fm24c16b - 16kb 5v i2c f - ram 6 january 2012 7 / 12 figure 7. current address read figure 8. sequential read figure 9. selective (random) read endurance the fm 24c16b internally operates with a read and restore mechanism. therefore, endurance cycles are applied for each read or write cycle. 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 fm24c16b, 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, fram read and write endurance is effectively un limited at the 1mhz two - wire speed. even at 3000 accesses per second to the same row, 10 years time will elapse before 1 trillion endurance cycles occur. s a slave address 1 data byte 1 p by master by fm 24 c 16 b start address stop acknowledge no acknowledge data s a slave address 1 data byte 1 p by master by fm 24 c 16 b start address stop acknowledge no acknowledge data data byte a acknowledge s a slave address 1 data byte 1 p by master by fm 24 c 16 b start address stop no acknowledge data data byte a acknowledge s a slave address 0 word address a start address acknowledge
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 8 of 12 electrical specifications absolute maximum ratings symbol description ratings v dd power supply v oltage with respect to v ss - 1.0v to +7.0v v in voltage on any signal 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) 26 0 ? c v esd electrostatic dischar ge voltage - human body model (aec - q100 - 002 rev. e) - charged device model (aec - q100 - 011 rev. b) - machine model ( a ec - q100 - 003 rev. e ) 4kv 1.25kv 100v package moisture sensitivity level msl - 1 * exception: the v in < v dd +1.0v restriction does no t apply to the scl and sda inputs. 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 li sted 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 (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 main power supply 4.5 5.0 5.5 v i dd vdd supply current @ scl = 100 khz @ scl = 400 khz @ scl = 1 mhz 100 200 400 ? a ? a ? a 1 i sb standby current 4 10 ? a 2 i li input leakage current 1 ? a 3 i lo output leakage current 1 ? a 3 v il input low voltage - 0.3 0.3 v dd v v ih input high voltage 0.7 v dd v dd + 0.3 v v ol output low voltage @ i ol = 3 ma 0.4 v r in input resistance (wp pin) for v in = v il (max) for v in = v ih (min) 4 0 1 k ? m ? 5 v hys input hysteresis 0.05 v dd v 4 notes 1. scl toggling between v dd - 0.3v and v ss , other inputs v ss or v dd - 0.3v. 2. scl = sda = v dd . all inputs v ss or v dd . stop command issued. 3. v in or v out = v ss to v dd . does not apply to wp pin . 4. this parameter is characterized but not tested. 5. the input pull - down circuit is strong ( 4 0k ? ) when the input voltage is below v il and much weaker (1m ? ) when the input voltage is above v ih .
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 9 of 12 a c parameters (t a = - 40 ? c to + 85 ? c, v dd = 4.5v to 5.5v unless otherwise specifie d) symbol parameter min max min max min max units notes f scl scl clock frequency 0 100 0 400 0 1000 khz 1 t low clock low period 4.7 1.3 0.6 ? s t high clock high period 4.0 0.6 0.4 ? s t aa scl low to sda data out valid 3 0.9 0.55 ? s t buf bus free before new transmission 4.7 1.3 0.5 ? s t hd:sta start condition hold time 4.0 0.6 0.25 ? s t su:sta start condition setup for repeated start 4.7 0.6 0.25 ? s t hd:dat data in hold time 0 0 0 ns t su:dat data in setup time 250 100 100 ns t r input rise time 1000 300 300 ns 2 t f input fall time 300 300 100 ns 2 t su:sto stop condition setup 4.0 0.6 0.25 ? s t dh data output hold (from scl @ v il ) 0 0 0 ns t sp noise suppression time constant on scl, sda 50 50 50 ns n otes : all scl specifications as well as start and stop conditions apply to both read and write operations. 1 the speed - related specifications are guaranteed characteristic points from dc to 1 mhz. 2 this parameter is periodically sampled and not 100% tested . capacitance ( t a = 25 ? c, f=1.0 mhz, v dd = 5v) symbol parameter max units notes c i/o input/ output c apacitance (sda) 8 pf 1 c in input c apacitance 6 pf 1 notes 1 this parameter is periodically sampled and not 100% tested. 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 power up (v dd min) to first access (start condition) 1 0 - ms t pd last access (stop condition) to power d own (v dd min) 0 - ? s t vr v dd rise time 30 - ? s/v 1 t vf v dd fall time 3 0 - ? s/v 1 notes 1. sl ope measured at any point on v dd waveform . v d d m i n . v d d s d a , s c l t v r t p d t p u t v f
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 10 of 12 ac test conditions equivalent ac load circuit input pulse levels 0.1 v dd to 0.9 v dd input rise and fall times 10 n s input and output timing levels 0.5 v dd diagram notes all start and stop timing parameters apply to both read and write cycles. clock specifications are identical for read and write cycles. write timing parameters apply to slave address, word address, and write data bits. functional relationships are illustrated in the relevant data sheet sections. these diagrams illustrate the timing parameters only. read bus timing write bus timing data r etention symbol parameter min max units notes t dr @ +85oc 10 - years @ +80oc 19 - years @ +75oc 38 - years t su:sda start t r t f stop start t buf t high 1/fscl t low t sp t sp acknowledge t hd:dat t su:d at t aa t dh scl sda t su:sto start stop start acknowledge t aa t hd:dat t hd:sta t su:dat scl sda 5.5v output 1700 ? 100 pf
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 11 of 12 mechanical drawing 8 - pin soic (jedec standard ms - 012 variation aa) refer to jedec ms - 012 for c omplete dimensions and notes. all dimensions in millimeters . soic package marking scheme legend: xxx xx x= part number, p= package type r=rev code, lllllll= lot code ric=ramtron intl corp, yy=year, ww=work week example: fm 24c16b , green soic package, year 2010, work week 49 fm 24c16b - g a 00002g1 ric1049 xxxx xxx - p rll llll l ricyyww p i n 1 3 . 9 0 0 . 1 0 6 . 0 0 0 . 2 0 4 . 9 0 0 . 1 0 0 . 1 0 0 . 2 5 1 . 3 5 1 . 7 5 0 . 3 3 0 . 5 1 1 . 2 7 0 . 1 0 m m 0 . 2 5 0 . 5 0 4 5 0 . 4 0 1 . 2 7 0 . 1 9 0 . 2 5 0 - 8 r e c o m m e n d e d p c b f o o t p r i n t 7 . 7 0 0 . 6 5 1 . 2 7 2 . 0 0 3 . 7 0
fm24c16b - 16kb 5v i2c f - ram rev. 3.0 jan. 2012 page 12 of 12 revision history revision date summary 1.0 11/ 10 /2010 initial release 1.1 12/20 /2010 changed v ih (max) to v dd +0.3v. 1.2 2/15/2011 changed t pu and t vf spec limits . 1.3 7/1 9/2011 added esd ratings. 3.0 1/6/2012 changed to production status. changed t vf spec.

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