Preliminary
FM3808
256Kb Bytewide FRAM w/ Real-Time Clock
Features
256K bit Ferroelectric Nonvolatile RAM
•
Organized as 32,752 x 8 bits
•
High Endurance 100 Billion (10
11
) Read/Writes
•
10 year Data Retention
•
NoDelay™ Writes
•
70 ns Access Time/ 130 ns Cycle Time
•
Built-in Low V
DD
Protection
System Supervisor Function
•
Programmable Clock/Calendar Alarm
•
Programmable Watchdog Timer
•
Power Supply Monitor
•
Interrupt Output - Programmable Active
High/Low
•
Control Settings Inherently Nonvolatile
•
Generates either Processor Reset or Interrupt
Real-Time Clock/Calendar Function
•
Clock Registers in Top 16 bytes of Address Space
•
Battery Backed Power
•
Tracks Seconds through Centuries in BCD Format
•
Tracks Leap Years through 2099
•
Runs from a 32.768 kHz Timekeeping Crystal
Description
The FM3808 combines a 256Kb FRAM array with a
real-time clock and a system supervisor function. An
external 32.768 kHz crystal drives the timekeeping
function. It maintains time and date settings in the
absence of system power through the use of a backup
battery power source. Data in the memory array does
not depend on the backup source, it remains
nonvolatile in FRAM. In addition to timekeeping, the
FM3808 includes a system supervisor to manage low
V
DD
power conditions and a watchdog timer function.
A programmable interrupt output pin allows the user
to select the supervisor functions and the polarity of
the signal.
Both the FRAM array and the timekeeping function
are accessed through the memory interface. The
upper 16-address locations of the memory space are
allocated to the timekeeping registers rather than to
memory. The FRAM array provides data retention
for 10 years in the absence of system power, and is
not dependent on the backup power source for the
clock. This eliminates system concerns over data loss
in a traditional battery-backed RAM solution. In
addition, clock and supervisor control settings are
implemented in FRAM rather than battery-backed
RAM, making them more dependable. The FM3808
offers guaranteed operation over an industrial
temperature range of -40°C to +85°C.
D
E
D S
N N
E G
06
M S I
20
M E
t.
t 4005
O D
e p
en M
C
S
cem 8+F
E W
y:
la 0
R E
Bu
ep 18
T N
e
t R FM
O R
im
rec n:
N O
t T
Di utio
F
as
No Sol
Low Power Operation
•
5V Operation for Memory and Clock Interface
•
Backup Voltage as low as 2.5V
•
25 mA I
DD
Active Current
•
1
µA
I
BAK
Clock Backup Current
Pin Configuration
A11
A9
A8
A13
WE
VBAK
INT
VDD
X1
X2
A14
A12
A7
A6
A5
A4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
VSS
DQ2
DQ1
DQ0
A0
A1
A2
A3
L
rn
lte
A
te
a
Ordering Information
FM3808-70-T
70 ns access, 32-pin TSOP
FM3808DK
DIP module development kit
Documentation for the DIP module development kit is
available separately.
This is a product in sampling or pre-production phase of develop-
ment. Characteristic data and other specifications are subject to
change without notice.
Rev. 1.3 (EOL)
Feb. 2006
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, (719) 481-7000
www.ramtron.com
Page 1 of 27
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
