fm3808 Ramtron Corporation, fm3808 Datasheet - Page 7

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

system power fails, the V
it crosses the voltage on the V
clock/calendar power will switch to the backup power
supply V
below, controls the switchover process as part of a
more complete power management circuit.
The following functions are powered from the backup
power source when V
Rev. 1.3 (EOL)
Feb. 2006
CF
Clock/calendar core
Alarm interrupt/comparator
INT pin (determined by ABE & AIE bits);
active low only
BAK
. The supervisor function, described
Years
8 bits
DD
< V
DD
BAK
voltage will drop. When
(backup mode) :
Figure 2. Real-Time Clock Core Block Diagram
BAK
Months
5 bits
supply pin, the
32.768 kHz
crystal
User Interface Registers
6 bits
Date
3 bits
Days
Oscillator
The following functions are not powered and are
disabled when V
Hours
6 bits
Flags connected to related functions
User interface
Watchdog timer
Power monitor & band-gap (V
Flags connected to related functions
All FRAM access & updates
Calibration operation
INT pin if programmed as active-high
Divider
Clock
DD
< V
Minutes
7 bits
LO
512 Hz
32 Hz
:
1 Hz
DD
Update
Seconds
Logic
7 bits
W
<
2.0V)
Page 7 of 27
FM3808
R