FM3808
Rev 1.1
May 2003
Page 3 of 28
Functional Truth Table
/CE
H
!
L
L
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
/WE
X
X
H
L
/OE
X
X
L
X
Function
Standby/Precharge
Latch Address
Read
Write
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.
Register Map Summary Table
Data
Address
7FFFh
7FFEh
7FFDh
7FFCh
7FFBh
7FFAh
7FF9h
7FF8h
7FF7h
7FF6h
7FF5h
7FF4h
7FF3h
7FF2h
7FF1h
7FF0h
D7
D6
D5
D4
D3
D2
D1
D0
Function
Years
Month
Date
Day
Hours
Minutes
Seconds
Control-NV
Watchdog
Range
00-99
1-12
1-31
1-7
0-23
0-59
0-59
10 years
years
months
date
0
0
0
0
0
0
0
0
0
0
0
10 mo
10 date
0
0
0
day
10 hours
hours
minutes
seconds
CAL2
WDT2
P/L
Alarm date
hours
Alarm minutes
Alarm seconds
10 minutes
10 seconds
reserved
WDT5
PFE
Alarm 10 date
Alarm 10 hours
Alarm 10 minutes
Alarm 10 seconds
/OSCEN
WDS
WIE
/Match
/Match
/Match
/Match
reserved
/WDW
AIE
0
0
CALS
WDT4
ABE
CAL3
WDT3
H/L
CAL1
WDT1
reserved
CAL0
WDT0
reserved Interrupts
Alarm Date
Alarm Hours
Alarm Minutes
Alarm Seconds
User-NV
Flags/Control
1-31
0-23
0-59
0-59
WDF
AF
PF
CF
TST
CAL
W
R
Note that the shaded register bits are implemented in FRAM, therefore data at these locations is retained even
without backup power.