Ramtron FM28V020-SG 256kbit bytewide f-ram memory Datasheet

Preliminary
FM28V020
256Kbit Bytewide F-RAM Memory
Features
256Kbit Ferroelectric Nonvolatile RAM
• Organized as 32Kx8
• 1014 Read/Write Cycles
• NoDelay™ Writes
• Page Mode Operation to 33MHz
• Advanced High-Reliability Ferroelectric Process
Superior to Battery-backed SRAM Modules
• No battery concerns
• Monolithic reliability
• True surface mount solution, no rework steps
• Superior for moisture, shock, and vibration
• Resistant to negative voltage undershoots
General Description
The FM28V020 is a 32K x 8 nonvolatile memory that
reads and writes like a standard SRAM. A
ferroelectric random access memory or F-RAM is
nonvolatile, which means that data is retained after
power is removed. It provides data retention for over
10 years while eliminating the reliability concerns,
functional disadvantages, and system design
complexities of battery-backed SRAM (BBSRAM).
Fast write timing and virtually unlimited write
endurance make F-RAM superior to other types of
memory.
SRAM Replacement
• JEDEC 32Kx8 SRAM pinout
• 60 ns Access Time, 90 ns Cycle Time
Low Power Operation
• 2.0V – 3.6V Power Supply
• Standby Current 90 µA (typ)
• Active Current 7 mA (typ)
Industry Standard Configurations
• Industrial Temperature -40° C to +85° C
• 28-pin “Green”/RoHS SOIC (-SG)
• 32-pin “Green”/RoHS TSOP (-TG)
Pin Configuration
NC
OE
A11
A9
A8
A13
WE
VDD
A14
A12
A7
A6
A5
A4
A3
NC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
TSOP-I
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
NC
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
VSS
DQ2
DQ1
DQ0
A0
A1
A2
NC
In-system operation of the FM28V020 is very similar
to other RAM devices and can be used as a drop-in
replacement for standard SRAM. Read and write
cycles may be triggered by /CE or simply by
changing the address. The F-RAM memory is
nonvolatile due to its unique ferroelectric memory
process. These features make the FM28V020 ideal
for nonvolatile memory applications requiring
frequent or rapid writes in the form of an SRAM.
Device specifications are guaranteed over the
industrial temperature range -40°C to +85°C.
Ordering Information
28-pin “Green”/RoHS SOIC
28-pin “Green”/RoHS SOIC,
Tape & Reel
FM28V020-TG
32-pin “Green”/RoHS TSOP
FM28V020-TGTR
32-pin “Green”/RoHS TSOP,
Tape & Reel
FM28V020-SG
FM28V020-SGTR
This is a product that has fixed target specifications but are subject
to change pending characterization results.
Rev. 1.1
Sept. 2009
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, (719) 481-7000
http://www.ramtron.com
Page 1 of 14
FM28V020 - 32Kx8 FRAM
A(14:3)
Row Decoder
Address Latch
A(14:0)
4K x 64
F-RAM Array
A(2:0)
...
Column Decoder
CE
WE
Control
Logic
OE
I/O Latch & Bus Driver
DQ(7:0)
Figure 1. Block Diagram
Pin Descriptions
Pin Name
Type
A(14:0)
Input
/CE
Input
/WE
Input
/OE
Input
DQ(7:0)
VDD
VSS
Rev. 1.1
Sept. 2009
I/O
Supply
Supply
Pin Description
Address inputs: The 15 address lines select one of 32,768 bytes in the F-RAM array. The
address value is latched on the falling edge of /CE. Addresses A(2:0) are used for page
mode read and write operations.
Chip Enable input: The device is selected and a new memory access begins on the falling
edge of /CE. The entire address is latched internally at this point.
Write Enable: A write cycle begins when /WE is asserted. The rising edge causes the
FM28V020 to write the data on the DQ bus to the F-RAM array. The falling edge of /WE
latches a new column address for fast page mode write cycles.
Output Enable: When /OE is low, the FM28V020 drives the data bus when valid data is
available. Deasserting /OE high tri-states the DQ pins.
Data: 8-bit bi-directional data bus for accessing the F-RAM array.
Supply Voltage
Ground
Page 2 of 14
FM28V020 - 32Kx8 FRAM
Functional Truth Table
/CE
/WE
H
X
H
↓
L
H
L
H
L
↓
L
↓
L
↓
X
↑
Notes:
1)
2)
3)
4)
Rev. 1.1
Sept. 2009
A(14:3)
X
V
No Change
Change
V
V
No Change
X
A(2:0)
X
V
Change
V
V
V
V
X
Operation
Standby/Idle
Read
Page Mode Read
Random Read
/CE-Controlled Write 2
/WE-Controlled Write 2, 3
Page Mode Write 4
Starts Precharge
H=Logic High, L=Logic Low, V=Valid Address, X=Don’t Care.
For write cycles, data-in is latched on the rising edge of /CE or /WE, whichever comes first.
/WE-controlled write cycle begins as a Read cycle and A(14:3) is latched then.
Addresses A(2:0) must remain stable for at least 15 ns during page mode operation.
Page 3 of 14
FM28V020 - 32Kx8 FRAM
Overview
The FM28V020 is a bytewide F-RAM memory
logically organized as 32,768 x 8 and is accessed
using an industry standard parallel interface. All data
written to the part is immediately nonvolatile with no
delay. The device offers page mode operation which
provides higher speed access to addresses within a
page (row). An access to a different page is triggered
by toggling the chip enable pin or simply by changing
the upper address A(14:3).
Memory Operation
Users access 32,768 memory locations with 8 data
bits each through a parallel interface. The F-RAM
array is organized as 8 blocks each having 512 rows.
Each row has 8 column locations, which allows fast
access in page mode operation. Once an initial
address has been latched by the falling edge of /CE,
subsequent column locations may be accessed
without the need to toggle the chip enable. When
either chip enable pin is deasserted, a precharge
operation begins. Writes occur immediately at the end
of the access with no delay. The /WE pin must be
toggled for each write operation.
Read Operation
A read operation begins on the falling edge of /CE.
The /CE-initiated access causes the address to be
latched and starts a memory read cycle if /WE is high.
Data becomes available on the bus after the access
time has been satisfied. Once the address has been
latched and the access completed, a new access to a
random location (different row) may begin while /CE
is still active. The minimum cycle time for random
addresses is tRC. Note that unlike SRAMs, the
FM28V020’s /CE-initiated access time is faster than
the address cycle time.
The FM28V020 will drive the data bus only when
/OE is asserted low and the memory access time has
been satisfied. 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 hi-Z.
Write Operation
Writes occur in the FM28V020 in the same time
interval as reads. The FM28V020 supports both /CEand /WE-controlled write cycles. In both 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 the device is activated with the chip enable.
In this case, the device begins the memory cycle as a
Rev. 1.1
Sept. 2009
write. The FM28V020 will not drive the data bus
regardless of the state of /OE as long as /WE is low.
Input data must be valid when the device is
deselected with the chip enable. In a /WE-controlled
write, the memory cycle begins when the device is
activated with the chip enable. The /WE signal falls
some time later. Therefore, the memory cycle begins
as a read. The data bus will be driven if /OE is low,
however it will hi-Z once /WE is asserted low. The
/CE- and /WE-controlled write timing cases are
shown on page 9. In the Write Cycle Timing 2
diagram, the data bus is shown as a hi-Z condition
while the chip is write-enabled and before the
required setup time. Although this is drawn to look
like a mid-level voltage, it is recommended that all
DQ pins comply with the minimum VIH/VIL operating
levels.
Write access to the array begins on the falling edge of
/WE after the memory cycle is initiated. The write
access terminates on the deassertion of /WE or /CE,
whichever comes first. A valid write operation
requires the user to meet the access time specification
prior to deasserting /WE or /CE. Data setup time
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. Data polling, a technique used with
EEPROMs to determine if a write is complete, is
unnecessary.
Page Mode Operation
The FM28V020 provides the user fast access to any
data within a row element. Each row has eight
column locations. An access can start anywhere
within a row and other column locations may be
accessed without the need to toggle the /CE pin. For
page mode reads, once the first data byte is driven
onto the bus, the column address inputs A(2:0) may
be changed to a new value. A new data byte is then
driven to the DQ pins. For page mode writes, the
first write pulse defines the first write access. While
the device is selected (/CE low), a subsequent write
pulse along with a new column address provides a
page mode write access.
Precharge Operation
The precharge operation is an internal condition in
which the state of the memory is preparing for a new
access. Precharge is user-initiated by driving at least
one of the chip enable signals to an inactive state. The
Page 4 of 14
FM28V020 - 32Kx8 FRAM
chip enable must remain inactive for at least the
minimum precharge time tPC.
Precharge is also activated by changing the upper
addess A(14:3). The current row is first closed prior
to accessing the new row. The device automatically
detects an upper order address change which starts a
precharge operation, the new address is latched, and
Endurance
The FM28V020 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. The F-RAM architecture is based on an array
of rows and columns. Rows are defined by A14-A3
and column addresses by A2-A0. The array is
organized as 4K rows of 8-bytes 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 new read data is valid within the tAA address
access time. Refer to the Read Cycle Timing 1
diagram on page 9. Likewise a similar sequence
occurs for write cycles. Refer to the Write Cycle
Timing 3 diagram on page 11. The rate at which
random addresses can be issued is tRC and tWC,
respectively.
The user may choose to write CPU instructions and
run them from a certain address space. The table
below shows endurance calculations for 256-byte
repeating loop, which includes a starting address, 7
page mode accesses, and a CE precharge. The
number of bus clocks needed to complete an 8-byte
transaction is 8+1 at lower bus speeds, but 9+2 at
33MHz due to initial read latency and an extra clock
to satisfy the device’s precharge timing constraint tPC.
The entire loop causes each byte to experience only
one endurance cycle.
F-RAM read and write
endurance is virtually unlimited even at 33MHz
system bus clock rate.
Table 1. Time to Reach 100 Trillion Cycles for Repeating 256-byte Loop
Bus Freq Bus Cycle
256-byte
Endurance
Endurance
Years to
(MHz)
Time (ns) Transaction Cycles/sec.
Cycles/year
Reach 1014
Cycles
Time (µ
µs)
12
30
10.56
33
94,690
2.98 x 10
33.5
40
12.8
40.6
25
78,125
2.46 x 1012
10
100
28.8
34,720
1.09 x 1012
91.7
5
200
57.6
17,360
5.47 x 1011
182.8
Rev. 1.1
Sept. 2009
Page 5 of 14
FM28V020 - 32Kx8 FRAM
SRAM Drop-In Replacement
The FM28V020 has been designed to be a drop-in
replacement for standard asynchronous SRAMs. The
device does not require /CE to toggle for each new
address. /CE may remain low indefinitely while VDD
is applied. When /CE is low, the device automatically
detects address changes and a new access begins. It
also allows page mode operation at speeds up to
33MHz.
A typical application is shown in Figure 2. It shows a
pullup resistor on /CE which will keep the pin high
during power cycles assuming the MCU/MPU pin tristates during the reset condition. The pullup resistor
value should be chosen to ensure the /CE pin tracks
VDD yet a high enough value that the current drawn
when /CE is low is not an issue.
VDD
FM28V020
R
when /WE is low is not an issue. A 10Kohm resistor
draws 330uA when /WE is low and VDD=3.3V.
VDD
FM28V020
R
MCU/
MPU
CE
WE
OE
A(14:0)
DQ(7:0)
Figure 3. Use of Pullup Resistor on /WE
The FM28V020 is backward compatible with the
256Kbit FM18L08 device. Operating the FM28V020
with /CE toggling low on every address is perfectly
acceptable.
CE
MCU/
MPU
WE
PCB Layout Recommendations
OE
A 0.1uF decoupling capacitor should be placed close
to pin 28 (VDD) and the ground side of the capacitor
should be connected to either a ground plane or low
impedance path back to pin 14 (VSS). It is best to use
a chip capacitor that has low ESR and has good high
frequency characteristics.
A(14:0)
DQ(7:0)
Figure 2. Typical Application using Pullup
Resistor on /CE
For applications that require the lowest power
consumption, the /CE signal should be active only
during memory accesses. Due to the external pullup
resistor, some supply current will be drawn while /CE
is low. When /CE is high, the device draws no more
than the maximum standby current ISB.
Note that if /CE is grounded, the user must be sure
/WE is not low at powerup or powerdown events. If
the chip is enabled and /WE is low during power
cycles, data corruption will occur. Figure 3 shows a
pullup resistor on /WE which will keep the pin high
during power cycles assuming the MCU/MPU pin tristates during the reset condition. The pullup resistor
value should be chosen to ensure the /WE pin tracks
VDD yet a high enough value that the current drawn
Rev. 1.1
Sept. 2009
If the controller drives the address and chip enable
from the same timing edge, it is best to keep the
address routes short and of equal length. A simple RC
circuit may be inserted in the chip enable path to
provide some delay and timing margin for the
FM28V020’s address setup time tAS.
As a general rule, the layout designer may need to
add series termination resistors to controller outputs
that have fast transitions or routes that are > 15cm in
length. This is only necessary if the edge rate is less
than or equal to the round trip trace delay. Signal
overshoot and ringback may be large enough to cause
erratic device behavior. It is best to add a 50 ohm
resistor (30 – 60 ohms) near the output driver
(controller) to reduce such transmission line effects.
Page 6 of 14
FM28V020 - 32Kx8 FRAM
Electrical Specifications
Absolute Maximum Ratings
Symbol
Description
VDD
Power Supply Voltage with respect to VSS
VIN
Voltage on any signal pin with respect to VSS
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
Ratings
-1.0V to +4.5V
-1.0V to +4.5V and
VIN < VDD+1V
-55°C to +125°C
260° C
TBD
TBD
TBD
MSL-1 (SOIC)
MSL-3 (TSOP)
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 = 2.0V to 3.6V unless otherwise specified)
Symbol Parameter
Min
Typ
Max
Units Notes
VDD
Power Supply
2.0
3.3
3.6
V
IDD
VDD Supply Current
7
12
mA
1
ISB
Standby Current – CMOS
90
150
2
µA
ILI
Input Leakage Current
3
±1
µA
ILO
Output Leakage Current
3
±1
µA
VIH
Input High Voltage
0.7 VDD
VDD + 0.3
V
VIL
Input Low Voltage
-0.3
0.3 VDD
V
VOH1
Output High Voltage (IOH = -1 mA, VDD=2.7V)
2.4
V
VOH2
Output High Voltage (IOH = -100 µA)
VDD-0.2
V
VOL1
Output Low Voltage (IOL = 2 mA, VDD=2.7V)
0.4
V
VOL2
Output Low Voltage (IOL = 150 µA)
0.2
V
Notes
1. VDD = 3.6V, /CE cycling at minimum cycle time. All inputs at CMOS levels (0.2V or VDD-0.2V), all DQ pins unloaded.
2. VDD = 3.6V, /CE at VDD, All other pins at CMOS levels (0.2V or VDD-0.2V).
3. VIN, VOUT between VDD and VSS.
Rev. 1.1
Sept. 2009
Page 7 of 14
FM28V020 - 32Kx8 FRAM
Read Cycle AC Parameters (TA = -40° C to +85° C, CL = 30 pF, unless otherwise specified)
VDD 2.0 to 2.7V
VDD 2.7 to 3.6V
Symbol Parameter
Min
Max
Min
Max
tRC
Read Cycle Time
105
90
tCE
Chip Enable Access Time
70
60
tAA
Address Access Time
105
90
tOH
Output Hold Time
20
20
tAAP
Page Mode Address Access Time
40
30
tOHP
Page Mode Output Hold Time
3
3
tCA
Chip Enable Active Time
70
60
tPC
Precharge Time
35
30
tAS
Address Setup Time (to /CE low)
0
0
tAH
Address Hold Time (/CE-controlled)
70
60
tOE
Output Enable Access Time
25
15
tHZ
Chip Enable to Output High-Z
10
10
tOHZ
Output Enable High to Output High-Z
10
10
Units
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Notes
Write Cycle AC Parameters (TA = -40° C to +85° C, unless otherwise specified)
VDD 2.0 to 2.7V
VDD 2.7 to 3.6V
Symbol Parameter
Min
Max
Min
Max
tWC
Write Cycle Time
105
90
tCA
Chip Enable Active Time
70
60
tCW
Chip Enable to Write Enable High
70
60
tPC
Precharge Time
35
30
tPWC
Page Mode Write Enable Cycle Time
40
30
tWP
Write Enable Pulse Width
22
18
tAS
Address Setup Time (to /CE low)
0
0
tAH
Address Hold Time (/CE-controlled)
70
60
tASP
Page Mode Address Setup Time (to /WE low)
8
5
tAHP
Page Mode Address Hold Time (to /WE low)
20
15
tWLC
Write Enable Low to /CE High
30
25
tWLA
Write Enable Low to A(14:3) Change
30
25
tAWH
A(14:3) Change to Write Enable High
105
90
tDS
Data Input Setup Time
20
15
tDH
Data Input Hold Time
0
0
tWZ
Write Enable Low to Output High Z
10
10
tWX
Write Enable High to Output Driven
5
5
tWS
Write Enable to /CE Low Setup Time
0
0
tWH
Write Enable to /CE High Hold Time
0
0
-
Units
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Notes
1
1
1
1
1,2
1,2
Notes
1
This parameter is characterized but not 100% tested.
2
The relationship between /CE and /WE determines if a /CE- or /WE-controlled write occurs.
Power Cycle Timing (TA = -40° C to +85° C, VDD = 2.0V to 3.6V unless otherwise specified)
Symbol
Parameter
Min
Max
tVR
VDD Rise Time
50
tVF
VDD Fall Time
100
tPU
Power Up (VDD min) to First Access Time
250
tPD
Last Access to Power Down (VDD min)
0
-
Units
µs/V
µs/V
µs
µs
Notes
1
1
Notes
1
Slope measured at any point on VDD waveform.
Rev. 1.1
Sept. 2009
Page 8 of 14
FM28V020 - 32Kx8 FRAM
Data Retention (VDD = 2.0V to 3.6V, +85°C)
Parameter
Data Retention
Capacitance (TA = 25° C , f=1 MHz, VDD = 3.3V)
Symbol
Parameter
CI/O
Input/Output Capacitance (DQ)
CIN
Input Capacitance
Notes
1. This parameter is characterized and not 100% tested.
AC Test Conditions
Input Pulse Levels
Input rise and fall times
Input and output timing levels
Output Load Capacitance
Min
10
Max
-
Units
Years
Notes
Min
-
Max
8
6
Units
pF
pF
Notes
1
1
0 to 3V
3 ns
1.5V
30 pF
Read Cycle Timing 1 (/CE low, /OE low)
tRC
A(14:0)
tAA
tOH
tOH
DQ(7:0)
Read Cycle Timing 2 (/CE-controlled)
tCA
tPC
CE
tAH
tAS
A(14:0)
tOE
tHZ
OE
tCE
tOHZ
DQ(7:0)
Rev. 1.1
Sept. 2009
Page 9 of 14
FM28V020 - 32Kx8 FRAM
Page Mode Read Cycle Timing
Although sequential column addressing is shown, it is not required.
Write Cycle Timing 1 (/WE-Controlled) Note: /OE is low only to show effect of /WE on DQ pins
tCA
tPC
tCW
CE
tWLC
tAS
A(14:0)
tWP
tWX
WE
DQ(7:0)
tWZ
tDH
tDS
D out
D in
tHZ
D out
Write Cycle Timing 2 (/CE-Controlled)
NOTE: See Write Operation section for detailed description (page 4).
Rev. 1.1
Sept. 2009
Page 10 of 14
FM28V020 - 32Kx8 FRAM
Write Cycle Timing 3 (/CE low) Note: /OE is low only to show effect of /WE on DQ pins
tWC
tAWH
A(14:0)
tWLA
WE
tWX
tWZ
DQ(7:0)
D out
tDS
D in
tDH
D out
D in
Page Mode Write Cycle Timing
Although sequential column addressing is shown, it is not required.
Power Cycle Timing
Rev. 1.1
Sept. 2009
Page 11 of 14
FM28V020 - 32Kx8 FRAM
Mechanical Drawing
28-pin SOIC (JEDEC MS-013D Variation AE)
All dimensions in millimeters
7.50 ±0.10
10.30 ±0.30
0.25
0.75
Pin 1
17.90 ±0.20
2.35
2.65
45 °
0.23
0.32
0?- 8?
1.27 typ
0.10
0.30
0.33
0.51
0.10
0.40
1.27
SOIC Package Marking Scheme
RAMTRON
XXXXXXX-P
RYYWWLLLLLLL
Legend:
XXXX= part number, P= package type (-SG)
R=Rev, YY=year, WW=work week, LLLLLL= lot code
Example: FM28V020, “Green”/RoHS SOIC package,
R=Rev. A, Year 2009, Work Week 23, Lot code 6340282
RAMTRON
FM28V020-SG
A09236340282
Rev. 1.1
Sept. 2009
Page 12 of 14
FM28V020 - 32Kx8 FRAM
32-pin Shrunk TSOP-I (8.0 x 13.4 mm)
All dimensions in millimeters
TSOP Package Marking Scheme
RAMTRON
XXXXXXX-P
YYWWLLLLLL
Rev. 1.1
Sept. 2009
Legend:
XXXXXX= part number, P= package/option (T=TSOP, S=SOIC)
R=rev code, YY=year, WW=work week, LLLLLL= lot code
Example: FM28V020-TG, “Green” TSOP package,
A rev., Year 2009, Work Week 31, Lot 6340282
RAMTRON
FM28V020-T
A09316340282
Page 13 of 14
FM28V020 - 32Kx8 FRAM
Revision History
Revision
1.0
1.1
Rev. 1.1
Sept. 2009
Date
4/15/2009
9/8/2009
Summary
Initial release.
Added TSOP package and MSL rating. Expanded explanation of precharge
operation. Updated lead temperature rating in Abs Max table.
Page 14 of 14