fm3808 Ramtron Corporation, fm3808 Datasheet - Page 3

• Manufacturer Part Number: fm3808
• Description: 256kb Bytewide Fram W/ Real-time Clock
• Manufacturer: Ramtron Corporation

Functional Truth Table
Overview
The FM3808 integrates three complementary but
distinct functions under a common interface in a
single package. First, is the 32Kx8 FRAM memory
block (minus 16 bytes), second is the real-time
clock/calendar, and third is the system supervisor.
The functions are integrated to enhance their
individual performance, so that each provides better
capability than three similar stand-alone devices. All
functions use the same bytewide address/data
interface and are memory mapped. Special functions,
including the clock/calendar and supervisor system,
are controlled via registers that reside in the top of the
Register Map Summary Table
Note that the shaded register bits are implemented in FRAM, therefore data at these locations is retained even
without backup power.
Rev. 1.3 (EOL)
Feb. 2006
Address
7FFFh
7FFEh
7FFDh
7FFCh
7FFBh
7FFAh
7FF9h
7FF8h
7FF7h
7FF6h
7FF5h
7FF4h
7FF3h
7FF2h
7FF1h
7FF0h
/CE
!
H
L
L
/OSCEN reserved reserved
/Match
/Match
/Match
/Match
WDS
WDF
WIE
D7
0
0
0
0
0
0
/WE
X
X
H
/WDW
L
AIE
D6
AF
0
0
0
0
0
0
10 years
Alarm 10 seconds
Alarm 10 minutes
10 seconds
10 minutes
WDT5
PFE
Alarm 10 hours
D5
Alarm 10 date
PF
0
0
10 hours
/OE
10 date
X
X
X
L
WDT4
10 mo
CALS
ABE
D4
CF
0
Data
Function
Standby/Precharge
Latch Address
Read
Write
WDT3
CAL3
TST
H/L
D3
0
WDT2
CAL2
Alarm seconds
CAL
P/L
Alarm minutes
D2
Alarm date
seconds
minutes
months
years
hours
hours
date
combined memory map. The register map is
described below, followed by a detailed description
of each functional block.
Register Map
The top 16 FRAM address locations control the
clock/calendar, alarm, and supervisor functions. The
registers contain timekeeping data, control bits, or
information flags. A short description of each register
follows. Detailed descriptions of each function follow
the register summary.
reserved reserved Interrupts
WDT1
CAL1
day
D1
W
WDT0
CAL0
D0
R
Years
Month
Date
Day
Hours
Minutes
Seconds
Control-NV
Watchdog
Alarm Date
Alarm Hours
Alarm Minutes
Alarm Seconds
User-NV
Flags/Control
Function
00-99
1-12
1-31
1-7
0-23
0-59
0-59
1-31
0-23
0-59
0-59
Range
Page 3 of 27
FM3808