FM31L278-G Ramtron, FM31L278-G Datasheet - Page 14

• Manufacturer Part Number: FM31L278-G
• Description: FRAM, MPU SUPPORT, 256K, RTC, SOIC14
• Manufacturer: Ramtron

Specifications of FM31L278-G

• Memory Size: 256Kbit
• Nvram Features: RTC
• Supply Voltage Range: 2.7V To 3.6V
• Memory Case Style: SOIC
• No. Of Pins: 14
• Operating Temperature Range: -40°C To +85°C
• Package / Case: SOIC
• Mounting Style: SMD/SMT
• Memory Configuration: 32768 X 8
• Interface Type: I2C, Serial, 2-Wire
• Rohs Compliant: Yes
• Number Of Voltages Monitored: 1
• Monitored Voltage: 2.6 V or 2.9 V
• Output Type: Active Low, Open Drain
• Manual Reset: Resettable
• Watchdog: Watchdog
• Battery Backup Switching: Yes
• Power-up Reset Delay (typ): 200 ms
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.7 V
• Supply Current (typ): 1500 uA
• Power Fail Detection: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Rev. 2.0
Jan. 2011
09h
WTR
POR
LB
WR3-0
08h
07h
06h
05h
04h
03h
02h
Watchdog Restart & Flags
Watchdog Timer Reset Flag: When a watchdog timer fault occurs, the WTR bit will be set to 1. It must be cleared
by the user. Note that both WTR and POR could be set if both reset sources have occurred since the flags were
cleared by the user. Battery-backed. Read/Write (internally set, user can clear bit).
Power-on Reset Flag: When the /RST pin is activated by V
cleared by the user. Note that both WTR and POR could be set if both reset sources have occurred since the flags
were cleared by the user. Battery-backed. Read/Write (internally set, user can clear bit).
Low Backup Flag: On power up, if the VBAK source is below the minimum voltage to operate the RTC and event
counters, this bit will be set to 1. The user should clear it to 0 when initializing the system. Battery-backed.
Read/Write (internally set, user can clear bit).
Watchdog Restart: Writing a pattern 1010b to WR3-0 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 timer. This allows
users to clear the WTR, POR, and LB flags without affecting the watchdog timer. Battery-backed, Write-only.
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
Contains the BCD value of hours in 24-hour format. Lower nibble contains the lower digit and operates from 0 to
9; upper nibble (two bits) contains the upper digit and operates from 0 to 2. The range for the register is 0-23.
Battery-backed, read/write.
Timekeeping – Minutes
Contains the BCD value of minutes. Lower nibble contains the lower digit and operates from 0 to 9; upper nibble
contains the upper minutes digit and operates from 0 to 5. The range for the register is 0-59. Battery-backed,
read/write.
Timekeeping – Seconds
Contains the BCD value of seconds. Lower nibble contains the lower digit and operates from 0 to 9; upper nibble
contains the upper digit and operates from 0 to 5. The range for the register is 0-59. Battery-backed, read/write.
10 year.3
WTR
D7
D7
D7
D7
D7
D7
D7
D7
0
0
0
0
0
0
10 year.2
10 min.2
10 sec.2
POR
D6
D6
D6
D6
D6
D6
D6
D6
0
0
0
0
10 hours.1
10 year.1
10 date.1
10 min.1
10 sec.1
D5
D5
D5
D5
D5
D5
D5
D5
LB
0
0
10 hours.0
10 Month
10 year.0
10 date.0
10 min.0
10 sec.0
D4
D4
D4
D4
D4
D4
D4
D4
0
-
FM31L278/L276/L274/L272 - 3V I2C Companion
Seconds.3
DD
Month.3
Hours.3
Year.3
Date.3
Min.3
WR3
D3
D3
D3
D3
D3
D3
D3
D3
< V
0
TP
, the POR bit will be set to 1. It must be
Seconds.2
Month.2
Hours2
Date.2
Year.2
Day.2
Min.2
WR2
D2
D2
D2
D2
D2
D2
D2
D2
Seconds.1
Month.1
Hours.1
Date.1
Year.1
Day.1
Min.1
WR1
D1
D1
D1
D1
D1
D1
D1
D1
Page 14 of 26
Seconds.0
Month.0
Hours.0
Date.0
Year.0
Day.0
Min.0
WR0
D0
D0
D0
D0
D0
D0
D0
D0