FM33256B-G Cypress Semiconductor, FM33256B-G Datasheet - Page 17

• Manufacturer Part Number: FM33256B-G
• Description: Real Time Clock 256Kb F-RAM Processor Companion
• Manufacturer: Cypress Semiconductor

Specifications of FM33256B-G

• Rohs: yes
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 2.7 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-14
• Factory Pack Quantity: 56

This product conforms to specifications per the terms of the Ramtron
standard warranty. The product has completed Ramtron’s internal
qualification testing and has reached production status.
Rev. 3.0
Aug. 2012
0Ah
WR(3:0)
09h
EWDF
LWDF
POR
LB
08h
07h
06h
05h
04h
Watchdog Restart
Watchdog Restart. Writing a pattern 1010b to WR(3:0) restarts the watchdog timer. The upper nibble contents
do not affect this operation. Writing any pattern other than 1010b to WR3-0 has no effect on the watchdog.
Write-only.
Watchdog Flags
Early Watchdog Timer Fault Flag: When a watchdog restart occurs too early (before the programmed watchdog
StartTime), the /RST pin is driven low and this flag is set. It must be cleared by the user. Note that both EWDF
and POR could be set if both reset sources have occurred since the flags were cleared by the user. Battery-
backed, read/write.
Late Watchdog Timer Fault Flag: When either a watchdog restart occurs too late (after the programmed
watchdog EndTime) or no restart occurs, the /RST pin is driven low and this flag is set. It must be cleared by the
user. Note that both LWDF and POR could be set if both reset sources have occurred since the flags were
cleared by the user. Battery-backed, read/write.
Power-On Reset: When the /RST signal is activated by V
will not set this flag. Note that one or both of the watchdog flags and the POR flag could be set if both reset
sources have occurred since the flags were cleared by the user. Battery-backed, read/write. (internally set, user
must clear bit)
Low Backup: If the V
V
values should be treated as unknown. The user should clear it to 0 when initializing the system. Battery-backed.
Read/Write (internally set, user must clear bit).
Timekeeping – Years
Contains the lower two BCD digits of the year. Lower nibble contains the value for years; upper nibble contains
the value for 10s of years. Each nibble operates from 0 to 9. The range for the register is 0-99. Battery-backed,
read/write.
Timekeeping – Months
Contains the BCD digits for the month. Lower nibble contains the lower digit and operates from 0 to 9; upper
nibble (one bit) contains the upper digit and operates from 0 to 1. The range for the register is 1-12. Battery-
backed, read/write.
Timekeeping – Date of the month
Contains the BCD digits for the date of the month. Lower nibble contains the lower digit and operates from 0 to
9; upper nibble contains the upper digit and operates from 0 to 3. The range for the register is 1-31. Battery-
backed, read/write.
Timekeeping – Day of the week
Lower nibble contains a value that correlates to day of the week. Day of the week is a ring counter that counts
from 1 to 7 then returns to 1. The user must assign meaning to the day value, as the day is not integrated with the
date. Battery-backed, read/write.
Timekeeping – Hours
10 year.3
EWDF
DD
D7
D7
D7
D7
D7
D7
D7
0
0
<V
0
-
BAK
232.5 ms
, this bit will be set to ‘1’. All registers need to be re-initialized since the battery-backed register
225 ms
10 year.2
LWDF
D6
D6
D6
D6
D6
D6
D6
0
0
0
-
BAK
source drops to a voltage level insufficient to operate the RTC/alarm when
10 year.1
10 date.1
750 ms
775 ms
POR
D5
D5
D5
D5
D5
D5
D5
0
0
-
10 Month
10 year.0
10 date.0
D4
D4
LB
D4
D4
D4
D4
D4
1
1
0
-
1
1
DD
Month.3
Year.3
Date.3
< V
WR3
D3
D3
D3
D3
D3
D3
D3
0
-
TP
1
1
, the POR bit will be set to 1. A manual reset
1850 Ramtron Drive, Colorado Springs, CO 80921
FM33256B SPI Companion w/ FRAM
Month.2
Year.2
Date.2
Day.2
Ramtron International Corporation
1
1
WR2
D2
D2
D2
D2
D2
D2
D2
-
(800) 545-FRAM, [phone]
0
1
Month.1
Date.1
Year.1
Day.1
WR1
D1
D1
D1
D1
D1
D1
D1
-
www.ramtron.com
Page 17 of 28
Month.0
Date.0
Year.0
Day.0
WR0
D0
D0
D0
D0
D0
D0
D0
-