RAMTRON FM24C16A Technical data

FM24C16A

16Kb FRAM Serial Memory

Features

16K bit Ferroelectric Nonvolatile RAM

• Organized as 2,048 x 8 bits

• High Endurance (10

• 45 year Data Retention

• NoDelay™ Writes

• Advanced High-Reliability Ferroelectric Process

Fast Two-wire Serial Interface

• Up to 1MHz maximum bus freq uency

• Direct hardware replacement for EEPROM

Description

The FM24C16A 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 over 45
years while eliminating the complexities, overhead,
and system level reliability problems caused by
EEPROM and other nonvolatile memories.

Unlike serial EEPROMs, the FM24C16A performs
write operations at bus speed. No write delays are
incurred. The next bus cycle may commence
immediately without the need for data polling. The
FM24C16A is capable of supporting 10
cycles, or a million times more write cycles than
EEPROM.

These capabilities make the FM24C16A ideal for
nonvolatile memory applications requiring frequent
or rapid writes. Examples range from data collection
where the number of write cycles may be critical, to
demanding industrial controls where the long write
time of EEPROM can cause data loss. The
combination of features allows the system to write
data more frequently, with less system overhead.

The FM24C16A provides substantial benefits to users
of serial EEPROM, and these benefits are available as
a hardware drop-in replacement. The FM24C16A is
available in an industry standard 8-pin SOIC and uses
a two-wire protocol. The specifications are
guaranteed over the industrial temperature range from

-40°C to +85°C.

12

) Read/Write Cycles

12

read/write

Low Power Operation

• 5V operation

• 150 µA Active Current (100 kHz)

• 10 µA Standby Current

Industry Standard Configurat ion

• Industrial Temperature -40° C to +85° C

• 8-pin SOIC (-S)

• “Green” 8-pin SOIC (-G)

Pin Configuration

NC
NC

NC

VSS

1
2
3
4

Pin Names Function

SDA Serial Data/Address
SCL Serial Clock
WP Write Protect
VDD Supply Voltage 5V
VSS Ground

8
7
6
5

VDD
WP
SCL
SDA

Ordering Information

FM24C16A-S 8-pin SOIC
FM24C16A-G “Green” 8-pin SOIC

This product conforms to specifications per the terms of the Ramtron Ramtron International Corporation
standard warranty. The product has completed Ramtron’s internal 1850 Ramtron Drive, Colorado Springs, CO 80921
qualification testing and has reached production status. (800) 545-FRAM, [phone]

Rev. 3.0
Mar. 2005 Page 1 of 12

www.ramtron.com

FM24C16A

Counter

SDA

SCL

WP

Pin Description

Pin Name Type Pin Description

SDA I/O Serial Data Address: This is a bi-directional data pin for the two-wire interface. It

SCL Input Serial Clock: The serial clock input for the two-wire interface. Data is clocked-out on

WP Input Write Protect: W hen WP is high, the entire array is write-protected. When WP is low,

VDD Supply Supply Voltage (5V)
VSS Supply Ground
NC - No connect

`

Serial to Parallel

Converter

Control Logic

Figure 1. Block Diagram

employs an open-drain output and is intended to be wire-OR’d with other devices on the
two-wire bus. The input buffer incorpo rates a Schmitt trigger for noise immunity and the
output driver includes slope control for falling edges. A pull-up resistor is required.

the falling edge and clocked-in on the rising edge.

all addresses may be written. This pin is internally pulled down.

Address

Latch

256 x 64

FRAM Array

8

Data Latch

Rev 3.0
Mar. 2005 Page 2 of 12

FM24C16A

Overview

The FM24C16A 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 FM24C16A and a serial
EEPROM with the same pinout relates to its superior
write performance.

Memory Architecture

When accessing the FM24C16A, 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 distinguish 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 each byte uniquely.

Most functions of the FM24C16A 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 cond ition 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 FM24C16A 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 data sheet tolerances to prevent
incorrect operation.

Two-wire Interface

The FM24C16A employs a bi-directional two-wire
bus protocol using few pins and little board space.
Figure 2 illustrates a typical system configuration
using the FM24C16A in a microcontroller-based
system. The industry standard two-wire bus is
familiar to many users but is described in this section.

By convention, any device tha t 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 signal for all operations. Any
device on the bus that is being controlled is a slave.
The FM24C16A is always a slave device.

The bus protocol is contr olled 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 Specifications section.

VDD

Rmin = 1.8 K?

Rmax = tR/Cbus

Microcontroller

SDA SCL

FM24C16A

Figure 2. Typical System Configuration

SDA SCL

Other Slave Dev ice

Rev 3.0
Mar. 2005 Page 3 of 12

FM24C16A

SCL

SDA

Stop

(Master)

Start

(Master)

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 FM24 C16A must end
with a Stop condition. If an operation 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 co ndition.

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 FM24C16A 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 lo w state while idle
improves robustness.

Acknowledge

The Acknowledge takes 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
receiver does not drive SDA low, the condition is a
No-Acknowledge and the operation is aborted.

7

Data bits

(Transmitter)

6

0

Data bit

(Transmitter)

Acknowledge

(Receiver)

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, the FM24C16A
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 last byte, this
will cause the FM24C16A 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 FM24C16A 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 FM24C16A. The device type allows
other 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 operation.

Rev 3.0
Mar. 2005 Page 4 of 12

FM24C16A

Slave ID

1 0 1 0 A2 A1 A0 R/W

Page

Select

Figure 4. Slave Address

Word Address

After the FM24C16A (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 address to be combined with the 3­bits of the page select to specify the exact byte to be
written. The complete 11-bit address is latched
internally.

No word ad dress occurs for a read oper ation, though
the 3-bit page select is latched internally. Reads
always 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 each data byte, just prior to the
acknowledge, the FM24C16A 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 to 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
FM24C16A can begin. For a read operation 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 FM24C16A will
accept 8 data bits from the master then send an
acknowledge. All data transfer occurs MSB (most
significant bit) first.

Memory Operation

The FM24C16A 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 FM24C16A and a similar
configuration EEPROM during writes. The complete
operation for both writes and reads is explained
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 data 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 technologies, 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
bit is transferred. It will be complete before the
acknowledge is sent. Therefore, if the user desires to
abort a write without altering the memory contents,
this should be done using start or stop condition pr ior
to the 8

th

data bit. The FM24C16A needs no page

buffering.

The memory array can be write protected using the
WP pin. Setting the WP pin to a high condition
(VDD) will write-protect all addresses. The
FM24C16A 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. Setting WP to a low
state (VSS) will deactivate this feature.

Figure 5 and 6 below illustrates both a single-byte
and multiple-byte writes.

th

data

Rev 3.0
Mar. 2005 Page 5 of 12

FM24C16A

By Master

By FM24C16

Start Address & Data Stop

S ASlave Address 0 Word Address A Data Byte A P

Acknowledge

Figure 5. Single Byte Write

By Master

By FM24C16

Start Address & Data Stop

S ASlave Address 0 Word Address A Data Byte A P

Acknowledge

Data ByteA

Figure 6. Multiple Byte Write

Read Operation

There are two types of read operations. They are
current address read and selective address read. In a
current address read, the FM24C16A uses the internal
address latch to supply the lower 8 address bits. In a
selective read, the user performs a procedure to set
these lower address bits to a specific value.

Current Address & Sequential Read
As mentioned above the FM24C16A 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

most likely create a bus contention as the FM24C16A
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

th

9

clock cycle and a stop in the 10th clock cycle.
This is illustrated in the diagrams below. This is
the preferred method.

2. The bus master issues a no-acknowledge in the

th

9

clock cycle and a start in the 10th.

3. The bus master issues a stop in the 9

cycle. Bus contention may result.

4. The bus master issues a start in the 9

th

clock

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.
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 FM24C16A 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. After each byte, the internal address counter
will be incremented. Each time the bus master
acknowledges a byte this indicates that the
FM24C16A should read out the next sequential byte.

Selective (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 b yte followed by

subsequent read o perations.

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. After the

FM24C16A 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.
There are four ways to properly terminate a read

operation. Failing to properly terminate the read will

Rev 3.0
Mar. 2005 Page 6 of 12

FM24C16A

The operation is now a current address read. This operation is illustrated in Figure 9.

No

Acknowledge

By Master

Start Address

S ASlave Address 1 Data Byte 1 P

Stop

By FM24C16

Acknowledge

Figure 7. Current Address Read

By Master

By FM24C16

Start Address

S ASlave Address 1 Data Byte 1 P

Acknowledge

Figure 8. Sequential Read

By Master

By FM24C16

Start

S ASlave Address 0 Word Address A

Address

Start Address

S ASlave Address 1 Data Byte 1 P

Acknowledge

Figure 9. Selective (Random) Read

Endurance

The FM24C16A internally operates with a read and
restore mechanism. Therefore, endurance cycles are
applied for each read or write cycle. The FRAM
architecture is based on an array of rows and
columns. Rows are defined by A10-A3. Each access
causes an endurance cycle for a row. Endurance can
be optimized by ensuring frequently accessed data is
placed in different rows. Regardless, FRAM read and
write endurance is effectively unlimited at the 1MHz

Data

No

Acknowledge

Data ByteA

Data

Acknowledge

Acknowledge

Data

Stop

No

Acknowledge

Data ByteA

two-wire speed. Even at 3000 accesses per second to

the same row, 10 years time will elapse before 1

trillion endurance cycles occur.

Stop

Rev 3.0
Mar. 2005 Page 7 of 12

FM24C16A

Electrical Specifications

Absolute Maximum Ratings

Symbol Description Ratings

VDD Power Supply Voltage with respect to VSS -1.0V to +7.0V

VIN Voltage on any signal pin with respect to VSS -1.0V to +7.0V

and V

T

Storage Temperature

STG

T

Lead Temperature (Soldering, 10 seconds)

LEAD

V

Electrostatic Discharge Voltage

ESD

- Human Body Model

- Charged Device Model

(JEDEC Std JESD22-A114-B)

(JEDEC Std JESD22-C101-A)

- Machine Model (JEDEC Std JESD22-A115-A)

Package Moisture Sensitivity Level MSL-1

* Exceptio n: The “VIN < VDD+1.0V” restriction does not 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 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 = 4.5V to 5.5V unless otherwise specified)

Symbol Parameter Min Typ Max Units Notes

VDD Main Power Supply 4.5 5.0 5.5 V

IDD VDD Supply Current

@ SCL = 100 kHz
@ SCL = 400 kHz
@ SCL = 1 MHz

115
400
800

ISB Standby Current 1 10

ILI Input Leakage Current ±1
ILO Output Leakage Current ±1
VIL Input Low Voltage -0.3 0.3 VDD V
VIH Input High Voltage 0.7 VDD V

VOL Output Low Voltage

@ I

= 3 mA

OL

RIN Input Resistance (WP pin)

For V
For V

V

Input Hysteresis 0.05 VDD V 4

HYS

= VIL

IN

= VIH

IN

(max)

(min)

50

1

Notes

1. SCL toggling between V

3. 2. SCL = SDA = V

4. 3. V

or V

IN

OUT

DD

= VSS to VDD. Does not apply to WP pin.

-0.3V and VSS, other inputs VSS or VDD-0.3V.

DD

. All inputs VSS or VDD. Stop command issued.

5. 4. This parameter is characterized but not tested.

6. 5. The input pull-down circuit is strong (50KΩ) when the input voltage is below V

when the input voltage is above V

.

IH

< VDD+1.0V *

IN

-55°C to +125°C
300° C

4kV
1kV

300V

150
500

1000

µA
µA
µA
µA
µA
µA

+ 0.5 V

DD

0.4

V

KΩ

MΩ

and much weaker (1MΩ)

IL

1

2
3
3

5

Rev 3.0
Mar. 2005 Page 8 of 12

FM24C16A

AC Parameters

(TA = -40° C to + 85° C, VDD = 4.5V to 5.5V unless otherwise specified)

Symbol Parameter Min Max Min Max Min Max Units Notes

f

SCL Clock Frequency 0 100 0 400 0 1000 kHz 1

SCL

t

Clock Low Period 4.7 1.3 0.6

LOW

t

Clock High Period 4.0 0.6 0.4

HIGH

tAA SCL Low to SDA Data Out Valid 3 0.9 0.55
t

Bus Free Before New Transmission 4.7 1.3 0.5

BUF

t

Start Condition Hold Time 4.0 0.6 0.25

HD:STA

t

Start Condition Setup for Rep eated

SU:STA

4.7 0.6 0.25

µs
µs
µs

µs
µs
µs

Start

t

Data In Hold Time 0 0 0 ns

HD:DAT

t

Data In Setup Time 250 100 100 ns

SU:DAT

tR Input Rise Time 1000 300 300 ns 2
tF Input Fall Time 300 300 100 ns 2
t

Stop Condition Setup 4.0 0.6 0.25

SU:STO

tDH Data Output Hold

(from SCL @ V

)

IL

tSP Noise Suppression Time Constant

Notes : 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.

on SCL, SDA

0 0 0 ns

50 50 50 ns

µs

Capacitance (T

= 25° C, f=1.0 MHz, VDD = 5V)

A

Symbol Parameter Max Units Notes

C

Input/Output Capacitance (SDA) 8 pF 1

I/O

CIN Input Capacitance 6 pF 1

Notes

1 This parameter is periodically sampled and not 100% tested.

AC Test Conditions

Input Pulse Levels 0.1 V

to 0.9 VDD

DD

Input rise and fall times 10 ns
Input and output timing levels 0.5 V

DD

Equivalent AC Load Circuit

5.5V

1700

Ω

Output

100 pF

Rev 3.0
Mar. 2005 Page 9 of 12

FM24C16A

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

t

t

R

HIGH

t

F

t

LOW

t

SP

t

SP

SCL

1/fSCL

t

AA

t

HD:DAT

t

SU:DAT

t

DH

Acknowledge

SDA

t

SU:SDA

Start

t

BUF

Stop Start

Write Bus Timing

t

HD:DAT

SCL

t

SU:STO

t

HD:STA

t

SU:DAT

t

AA

SDA

Start

Stop Start Acknowledge

Data Retention

(VDD = 4.5V to 5.5V, +85° C)

Parameter Min Units Notes

Data Retention 45 Years

Rev 3.0
Mar. 2005 Page 10 of 12

FM24C16A

Mechanical Drawing

8-pin SOIC (JEDEC Standard MS-012 variation AA)

3.90 ±0.10 6.00 ±0.20

Recommended PCB Footprint

7.70

3.70

2.00

Pin 1

1.27

4.90 ±0.10

0.33

0.51

0.10

0.25

1.35

1.75

0.10 mm

1.27

0.25

0.50

0°-8°

45

°

0.65

0.19

0.25

0.40

1.27

Refer to JEDEC MS-012 for complete dimensions and notes.
All dimensions in millimeters

.

SOIC Package Marking Scheme

Legend:
XXXX= part number, P= package type
LLLLLLL= lot code
RIC=Ramtron Int’l Corp, Y Y=year, WW=work week

Example: FM24C16A, Standard SOIC package, Year 2004, Work Week 39
FM24C16A-S
A40003S
RIC0439

XXXXXXX-P
LLLLLLL

RICYYWW

Rev 3.0
Mar. 2005 Page 11 of 12

FM24C16A

Revision History

Revision

0.1 6/26/02 Initial Release

2.0 7/23/03 Changed to Production status.

2.1 3/17/04 Added “green” package. Updated package drawing.

3.0 3/29/05 Changed Data Retention spec. Added ESD and package MSL ratings. Added

Date

Summary

pcb footprint drawing. New rev. number and 1
new scheme.

st

page footer to comply with

Rev 3.0
Mar. 2005 Page 12 of 12