Maxim DS3065W 3.3v single-piece 8mb nonvolatile sram with clock Datasheet

Rev 0; 4/05
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
The DS3065W consists of a static RAM, a nonvolatile
(NV) controller, a year 2000-compliant real-time clock
(RTC), and an internal rechargeable manganese lithium
(ML) battery. These components are encased in a surface-mount module with a 256-ball BGA footprint.
Whenever VCC is applied to the module, it recharges
the ML battery, powers the clock and SRAM from the
external power source, and allows the contents of the
clock registers or SRAM to be modified. When VCC is
powered down or out-of-tolerance, the controller writeprotects the memory contents and powers the clock
and SRAM from the battery. The DS3065W also contains a power-supply monitor output (RST), as well as a
user-programmable interrupt output (IRQ/FT).
Applications
Features
♦ Single-Piece, Reflowable, 27mm x 27mm BGA
Package Footprint
♦ Internal Manganese Lithium Battery and Charger
♦ Integrated Real-Time Clock
♦ Unconditionally Write-Protects the Clock and
SRAM when VCC is Out-of-Tolerance
♦ Automatically Switches to Battery Supply when
VCC Power Failures Occur
♦ Reset Output can be Used as a CPU Supervisor
♦ Interrupt Output can be Used as a CPU Watchdog
Timer
RAID Systems and Servers
Gaming
POS Terminals
Fire Alarms
♦ Industrial Temperature Range (-40°C to + 85°C)
Industrial Controllers
PLCs
♦ UL Recognized
Data-Acquisition Systems
Routers/Switches
Ordering Information
PART
DS3065W-100
TEMP RANGE
PIN-PACKAGE
SPEED
SUPPLY VOLTAGE (%)
-40°C to +85°C
256-ball 27mm x 27mm BGA Module
100ns
3.3V ±0.3V
Typical Operating Circuit
CE
CE
WR
WE
RD
OE
CS
CS
DS3065W
MICROPROCESSOR
OR DSP DATA
8 BITS
DQ0–7
ADDRESS
20 BITS
A0–19
INT
IRQ/FT
INT
RST
1024k x 8
NV SRAM
AND RTC
Pin Configuration appears at end of data sheet.
______________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
DS3065W
General Description
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground......-0.3V to +4.6V
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range ...............................-40°C to +85°C
Soldering Temperature Range .......See IPC/JEDEC J-STD-020C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
(TA = -40°C to +85°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
3.3
MAX
UNITS
Supply Voltage
VCC
3.0
3.6
V
Input Logic 1
VIH
2.2
VCC
V
Input Logic 0
VIL
0.0
0.4
V
MAX
UNITS
µA
DC ELECTRICAL CHARACTERISTICS
(VCC = 3.3V ±0.3V, TA = -40°C to +85°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
Input Leakage Current
IIL
-1.0
+1.0
I/O Leakage Current
IIO
CE = CS = VCC
-1.0
+1.0
Output-Current High
IOH
At 2.4V
-1.0
mA
IOL
At 0.4V
2.0
mA
At 0.4V (Note 1)
8.0
mA
IOL IRQ/FT At 0.4V (Note 1)
7.0
mA
Output-Current Low
Output-Current Low RST
Output-Current Low IRQ/FT
Standby Current
Operating Current
Write Protection Voltage
IOL RST
ICCS1
CE = CS = 2.2V
0.5
7
ICCS2
CE = CS = VCC - 0.2V
0.2
5
ICCO1
tRC = 200ns, outputs open
VTP
µA
mA
50
mA
2.8
2.9
3.0
V
MIN
TYP
MAX
UNITS
PIN CAPACITANCE
(TA = +25°C.)
PARAMETER
Input Capacitance
Input/Output Capacitance
2
SYMBOL
CONDITIONS
CIN
Not production tested
15
pF
COUT
Not production tested
15
pF
_____________________________________________________________________
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
(VCC = 3.3V ±0.3V, TA = -40°C to +85°C.)
PARAMETER
Read Cycle Time
Access Time
OE to Output Valid
SYMBOL
CONDITIONS
tRC
DS3065W-100
MIN
MAX
100
UNITS
ns
tACC
100
ns
tOE
50
ns
ns
RTC OE to Output Valid
tOEC
60
CE or CS to Output Valid
tCO
100
OE or CE or CS to Output Active
tCOE
Output High Impedance from
Deselection
tOD
Output Hold from Address
tOH
Write Cycle Time
tWC
Write Pulse Width
tWP
Address Setup Time
tAW
(Note 2)
5
ns
ns
(Note 2)
40
ns
5
ns
100
ns
75
ns
0
ns
(Note 3)
tWR1
(Note 4)
5
tWR2
(Note 5)
20
Output High Impedance
from WE
tODW
(Note 2)
Output Active from WE
tOEW
(Note 2)
5
ns
tDS
(Note 6)
40
ns
tDH1
(Note 4)
0
tDH2
(Note 5)
20
Write Recovery Time
Data Setup Time
Data Hold Time
Chip-to-Chip Setup Time
ns
40
tCCS
ns
ns
40
ns
POWER-DOWN/POWER-UP TIMING
(TA = -40°C to +85°C.)
PARAMETER
VCC Fail Detect to CE, CS, and
WE Inactive
SYMBOL
tPD
CONDITIONS
MIN
TYP
(Note 7)
MAX
UNITS
1.5
µs
VCC Slew from VTP to 0V
tF
150
µs
VCC Slew from 0V to VTP
tR
150
µs
VCC Valid to CE, CS, and WE
Inactive
tPU
2
ms
VCC Valid to End of Write
Protection
tREC
125
ms
VCC Fail Detect to RST Active
tRPD
(Note 1)
VCC Valid to RST Inactive
tRPU
(Note 1)
40
350
3.0
µs
525
ms
_____________________________________________________________________
3
DS3065W
AC ELECTRICAL CHARACTERISTICS
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
DATA RETENTION
(TA = +25°C.)
PARAMETER
Expected Data-Retention Time
(Per Charge)
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
Note 12:
Note 13:
4
SYMBOL
tDR
CONDITIONS
(Notes 7, 8)
MIN
TYP
2
3
MAX
UNITS
years
IRQ/FT and RST are open-drain outputs and cannot source current. External pullup resistors should be connected to these
pins to realize a logic-high level.
These parameters are sampled with a 5pF load and are not 100% tested.
tWP is specified as the logical AND of CE with WE for SRAM writes, or CS with WE for RTC writes. tWP is measured from
the latter of the two related edges going low to the earlier of the two related edges going high.
tWR1 and tDH1 are measured from WE going high.
tWR2 and tDH2 are measured from CE going high for SRAM writes or CS going high for RTC writes.
tDS is measured from the earlier of CE or WE going high for SRAM writes, or from the earlier of CS or WE going high for
RTC writes.
In a power-down condition, the voltage on any pin may not exceed the voltage on VCC.
The expected tDR is defined as accumulative time in the absence of VCC starting from the time power is first applied by the
user. Minimum expected data-retention time is based upon a maximum of two +230°C convection reflow exposures, followed by a fully charged cell. Full charge occurs with the initial application of VCC for a minimum of 96 hours. This parameter is assured by component selection, process control, and design. It is not measured directly during production testing.
WE is high for any read cycle.
OE = VIH or VIL. If OE = VIH during write cycle, the output buffers remain in a high-impedance state.
If the CE or CS low transition occurs simultaneously with or latter than the WE low transition, the output buffers remain in a
high-impedance state during this period.
If the CE or CS high transition occurs prior to or simultaneously with the WE high transition, the output buffers remain in a
high-impedance state during this period.
If WE is low or the WE low transition occurs prior to or simultaneously with the related CE or CS low transition, the output
buffers remain in a high-impedance state during this period.
_____________________________________________________________________
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
tRC
ADDRESSES
VIH
VIH
VIH
VIL
VIL
VIL
tOH
tACC
CE
OR
CS
VIH
VIH
tCO
VIL
tOEC
tOE
VIH
OE
tOD
VIH
VIL
tOD
tCOE
tCOE
DOUT
VOH
VOL
OUTPUT
DATA VALID
VOH
VOL
(SEE NOTE 9.)
_____________________________________________________________________
5
DS3065W
Read Cycle
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
DS3065W
Write Cycle 1
tWC
ADDRESSES
VIH
VIL
VIH
VIL
VIH
VIL
tAW
CE
OR
CS
VIL
VIL
tWP
WE
VIH
tWR1
VIL
VIH
VIL
tOEW
tODW
HIGH
IMPEDANCE
DOUT
tDS
tDH1
VIH
VIH
DIN
DATA IN STABLE
VIL
VIL
(SEE NOTES 2, 3, 4, 6, 10–13.)
Write Cycle 2
tWC
ADDRESSES
VIH
VIL
tAW
CE
OR
CS
VIH
VIH
VIL
VIL
tWR2
tWP
VIH
VIH
VIL
VIL
VIL
VIH
WE
VIL
VIL
tODW
tCOE
DOUT
tDH2
tDS
VIH
VIH
DIN
DATA IN STABLE
VIL
(SEE NOTES 2, 3, 5, 6, 10–13.)
6
_____________________________________________________________________
VIL
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
VCC
VTP
tDR
~2.5V
tF
tR
tREC
tPD
tPU
SLEWS WITH
VCC
CE,
WE
AND
CS
VIH
BACKUP CURRENT
SUPPLIED FROM
LITHIUM BATTERY
tRPU
tRPD
RST
VOL
VOL
(SEE NOTES 1, 7.)
Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT (mA)
5
4
5MHz ADDRESSACTIVATED
100% DUTY CYCLE
3
2
1MHz CE-ACTIVATED
50% DUTY CYCLE
0
3.0
3.1
3.2
3.3
VCC (V)
900
800
700
500
3.4
3.5
3.6
8
DS3065W toc03
VCC = CE = 3.3V,
VBAT = VCHARGE,
OSC = ON
600
1MHz ADDRESSACTIVATED
100% DUTY CYCLE
1
DS3065W toc02
5MHz CE-ACTIVATED
50% DUTY CYCLE
SUPPLY CURRENT (µA)
TA = +25°C
6
1000
DS3065W toc01
7
BATTERY CHARGER CURRENT
vs. BATTERY VOLTAGE
BATTERY CHARGER CURRENT, ICHARGE (mA)
SUPPLY CURRENT
vs. OPERATING FREQUENCY
VCC = CE = 3.3V
7
6
5
4
3
2
1
VCHARGE = 2.86V
0
3.0
3.1
3.2
3.3
VCC (V)
3.4
3.5
3.6
0
0.2
0.4
0.6
0.8
1.0
DELTA V BELOW VCHARGE (V)
_____________________________________________________________________
7
DS3065W
Power-Down/Power-Up Condition
Typical Operating Characteristics (continued)
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
WRITE PROTECTION VOLTAGE
vs. TEMPERATURE
WRITE PROTECT, VTP (V)
0.5
0
-0.5
3.5
VCC = 3.3V
3.3
2.95
VOH (V)
VCC = 3.3V,
VBAT = VCHARGE
DS3065W toc05
3.00
DS3065W toc04
1.0
DQ OUTPUT-VOLTAGE HIGH
vs. DQ OUTPUT-CURRENT HIGH
2.90
-40
-15
10
35
2.85
2.7
2.5
-40
85
60
3.1
2.9
2.80
-1.0
DS3065W toc06
VCHARGE PERCENT CHANGE
vs. TEMPERATURE
VCHARGE PERCENT CHANGE FROM 25°C (%)
-15
10
35
85
60
-5
-4
-3
TEMPERATURE (°C)
TEMPERATURE (°C)
-2
IOH (mA)
DQ OUTPUT-VOLTAGE LOW
vs. DQ OUTPUT-CURRENT LOW
IRQ/FT OUTPUT-VOLTAGE LOW
vs. OUTPUT-CURRENT LOW
VCC = 3.3V
DS3065W toc08
6
DS3065W toc07
4
5
3
VOL (V)
VOL (V)
4
2
3
2
1
1
0
1
2
3
4
0
5
0
5
20
15
IOL (mA)
RST OUTPUT-VOLTAGE LOW
vs. OUTPUT-CURRENT LOW
RST VOLTAGE
vs. VCC DURING POWER-UP
5
4
3
2
1
4.0
DS3065W toc10
DS3065W toc09
6
TA = +25°C
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
0
5
10
15
20
0
0.5
1.0
IOL (mA)
8
10
IOL (mA)
RST VOLTAGE W/PULLUP RESISTOR (V)
0
VOL (V)
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
_____________________________________________________________________
1.5
2.0
2.5
VCC POWER-UP (V)
3.0
3.5
4.0
-1
0
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
BALLS
A1, A2, A3, A4
B1, B2, B3, B4
NAME
GND
DESCRIPTION
Ground
Interrupt/Frequency Test
IRQ/FT
Output
BALLS
NAME
DESCRIPTION
N17, N18, N19, N20
A5
Address Input 5
P17, P18, P19, P20
A4
Address Input 4
R17, R18, R19, R20
A3
Address Input 3
C1, C2, C3, C4
A15
Address Input 15
T17, T18, T19, T20
A2
Address Input 2
D1, D2, D3, D4
A16
Address Input 16
U17, U18, U19, U20
A1
Address Input 1
E1, E2, E3, E4
RST
Reset Output
V17, V18, V19, V20
A0
Address Input 0
F1, F2, F3, F4
VCC
Supply Voltage
W17, W18, W19, W20
GND
G1, G2, G3, G4
WE
Write Enable Input
Y17, Y18, Y19, Y20
GND
Ground
H1, H2, H3, H4
OE
Output Enable Input
A5, B5, C5, D5
N.C.
No Connection
CE
J1, J2, J3, J4
Ground
SRAM Chip Enable Input
A6, B6, C6, D6
N.C.
No Connection
K1, K2, K3, K4
DQ7
Data Input/Output 7
A7, B7, C7, D7
N.C.
No Connection
L1, L2, L3, L4
DQ6
Data Input/Output 6
A8, B8, C8, D8
N.C.
No Connection
M1, M2, M3, M4
DQ5
Data Input/Output 5
A9, B9, C9, D9
N.C.
No Connection
N1, N2, N3, N4
DQ4
Data Input/Output 4
A10, B10, C10, D10
VCC
Supply Voltage
P1, P2, P3, P4
DQ3
Data Input/Output 3
A11, B11, C11, D11
N.C.
No Connection
R1, R2, R3, R4
DQ2
Data Input/Output 2
A12, B12, C12, D12
N.C.
No Connection
T1, T2, T3, T4
DQ1
Data Input/Output 1
A13, B13, C13, D13
N.C.
No Connection
U1, U2, U3, U4
DQ0
Data Input/Output 0
A14, B14, C14, D14
N.C.
No Connection
V1, V2, V3, V4
GND
Ground
A15, B15, C15, D15
A19
Address Input 19
W1, W2, W3, W4
GND
Ground
A16, B16, C16, D16
N.C.
No Connection
Y1, Y2, Y3, Y4
GND
Ground
U5, V5, W5, Y5
CS
A17, A18, A19, A20
GND
Ground
U6, V6, W6, Y6
N.C.
No Connection
B17, B18, B19, B20
A18
Address Input 18
U7, V7, W7, Y7
N.C.
No Connection
C17,C18,C19, C20
A17
Address Input 17
U8, V8, W8, Y8
N.C.
No Connection
D17, D18, D19, D20
A14
Address Input 14
U9, V9, W9, Y9
N.C.
No Connection
E17, E18, E19, E20
A13
Address Input 13
U10, V10, W10, Y10
N.C.
No Connection
F17, F18, F19, F20
A12
Address Input 12
U11, V11, W11, Y11
N.C.
No Connection
G17, G18, G19, G20
A11
Address Input 11
U12, V12, W12, Y12
N.C.
No Connection
H17, H18, H19, H20
A10
Address Input 10
U13, V13, W13, Y13
N.C.
No Connection
J17, J18, J19, J20
A9
Address Input 9
U14, V14, W14, Y14
N.C.
No Connection
K17, K18, K19, K20
A8
Address Input 8
U15, V15, W15, Y15
N.C.
No Connection
L17, L18, L19, L20
A7
Address Input 7
U16, V16, W16, Y16
N.C.
No Connection
M17, M18, M19, M20
A6
Address Input 6
RTC Chip Select
_____________________________________________________________________
9
DS3065W
Pin Description
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
DS3065W
Functional Diagram
32.768kHz
IRQ/FT
REAL-TIME
CLOCK
RST
CS
CS
A0-A3
WE
OE
CE
DELAY TIMING
CIRCUITRY
VTP REF
CHARGER
CURRENT-LIMITING
RESISTOR
UNINTERRUPTED
POWER SUPPLY
FOR THE SRAM
AND RTC
VCC
VCC
CE
OE
WE
VSW REF
SRAM
REDUNDANT LOGIC
ML
GND
CURRENT-LIMITING
RESISTOR
REDUNDANT
SERIES FET
BATTERY-CHARGING/SHORTING
PROTECTION CIRCUITRY (U.L. RECOGNIZED)
OE
WE
A0–A19
10
____________________________________________________________________
DS3065W
DQ0–7
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
The DS3065W is an 8Mb (1024k x 8 bits) fully static, NV
memory similar in function and organization to the
DS1265W NV SRAM, but also containing an RTC and
rechargeable ML battery. The DS3065W NV SRAM constantly monitors VCC for an out-of-tolerance condition.
When such a condition occurs, the lithium energy source
is automatically switched on and write protection is
unconditionally enabled to prevent data corruption. There
is no limit to the number of write cycles that can be executed, and no additional support circuitry is required for
microprocessor interfacing. This device can be used in
place of SRAM, EEPROM, or flash components.
User access to either the SRAM or the real-time clock
registers is accomplished with a byte-wide interface
and discrete control inputs, allowing for a direct interface to many 3.3V microprocessor devices.
The DS3065W RTC contains a full-function, year 2000compliant (Y2KC) clock/calendar with an RTC alarm,
watchdog timer, battery monitor, and power monitor.
RTC registers contain century, year, month, date, day,
hours, minutes, and seconds data in a 24-hour BCD
format. Corrections for day of the month and leap year
are made automatically.
The DS3065W RTC registers are double-buffered into
an internal and external set. The user has direct access
to the external set. Clock/calendar updates to the external set of registers can be disabled and enabled to
allow the user to access static data. Assuming the
internal oscillator is on, the internal registers are contin-
ually updated, regardless of the state of the external
registers, assuring that accurate RTC information is
always maintained.
The DS3065W contains interrupt (IRQ/FT) and reset
(RST) outputs, which can be used to control CPU activity. The IRQ/FT interrupt output can be used to generate an external interrupt when the RTC register values
match user-programmed alarm values. The interrupt is
always available while the device is powered from the
system supply, and it can be programmed to occur
when in the battery-backed state to serve as a system
wake-up. The IRQ/FT output can also be used as a
CPU watchdog timer. CPU activity is monitored and an
interrupt can be activated if the correct activity is not
detected. The RST output can be used to detect a system power-down or failure and hold the CPU in a safe
state until normal power returns.
The DS3065W constantly monitors the voltage of the
internal battery. The battery-low flag (BLF) in the RTC
FLAGS register is not writeable and should always be a
0 when read. Should a 1 ever be present, the battery
voltage is below ∼2V and the contents of the clock and
SRAM are questionable.
The DS3065W module is constructed on a standard 256ball, 27mm x 27mm BGA substrate. Unlike other surface-mount NV memory modules that require the battery
to be removable for soldering, the internal ML battery
can tolerate exposure to convection reflow soldering
temperatures, allowing this single-piece component to
be handled with standard BGA assembly techniques.
Table 1. RTC/Memory Operational Truth Table
CS
WE
CE
OE
MODE
ICC
OUTPUTS
0
1
1
0
RTC Read
Active
Active
0
1
1
1
RTC Read
Active
High Impedance
0
0
1
X
RTC Write
Active
High Impedance
1
1
0
0
SRAM Read
Active
Active
1
1
0
1
SRAM Read
Active
High Impedance
1
0
0
X
SRAM Write
Active
High Impedance
1
X
1
X
Standby
Standby
High Impedance
0
X
0
X
Invalid (1)
Active
Invalid
X = Don’t care. (1) = See Figure 4.
____________________________________________________________________
11
DS3065W
Detailed Description
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
SRAM Read Mode
SRAM Write Mode
The DS3065W executes an SRAM read cycle whenever
CS (RTC chip select) and WE (write enable) are inactive
(high) and CE (SRAM chip enable) is active (low). The
unique address specified by the 20 address inputs (A0
to A19) defines which of the 1,048,576 bytes of SRAM
data is to be accessed. Valid data will be available to the
eight data output drivers within tACC (access time) after
the last address input signal is stable, providing that CE
and OE (output enable) access times are also satisfied.
If CE and OE access times are not satisfied, then data
access must be measured from the later occurring signal (CE or OE) and the limiting parameter is either tCO for
CE or tOE for OE rather than address access.
The DS3065W executes an SRAM write cycle whenever
CS is inactive (high) and the CE and WE signals are
active (low) after address inputs are stable. The lateroccurring falling edge of CE or WE determines the start of
the write cycle. The write cycle is terminated by the earlier
rising edge of CE or WE. All address inputs must be kept
valid throughout the write cycle. WE must return to the
high state for a minimum recovery time (tWR) before
another cycle can be initiated. The CS and OE control
signal should be kept inactive (high) during SRAM write
cycles to avoid bus contention. However, if the output drivers have been enabled (CE and OE active) then WE disables the outputs in tODW from its falling edge.
Clock Operations
Table 2. RTC Register Map
ADDRESS
DATA
B7
B6
xxxxEh
X
X
xxxxDh
X
X
xxxxCh
X
FT
xxxxBh
X
X
xxxxFh
B5
B4
B3
B1
10 YEAR
X
10 M
X
B0
YEAR
YEAR
00–99
MONTH
01–12
DATE
DATE
01–31
X
DAY
10 HOUR
FUNCTION/RANGE
MONTH
10 DATE
X
HOUR
DAY
01–07
HOUR
00–23
xxxxAh
X
10 MINUTES
MINUTES
MINUTES
00–59
xxxx9h
OSC
10 SECONDS
SECONDS
SECONDS
00–59
xxxx8h
W
R
CENTURY
CONTROL
00–39
xxxx7h
WDS
BMB4
BMB3
BMB2
BMB1
BMB0
RB1
RB0
WATCHDOG

xxxx6h
AE
Y
ABE
Y
Y
Y
Y
Y
INTERRUPTS

xxxx5h
AM4
Y
10 DATE
DATE
ALARM DATE
01–31
xxxx4h
AM3
Y
10 HOURS
HOURS
ALARM
HOURS
00–23
xxxx3h
AM2
10 MINUTES
MINUTES
ALARM
MINUTES
00–59
xxxx2h
AM1
10 SECONDS
SECONDS
ALARM
SECONDS
00–59
10 CENTURY
xxxx1h
Y
Y
Y
Y
Y
Y
Y
Y
UNUSED

xxxx0h
WF
AF
0
BLF
0
0
0
0
FLAGS

x = Don’t care address bits.
X = Unused. Read/writeable under write and read bit control.
FT = Frequency test bit.
OSC = Oscillator start/stop bit.
W = Write bit.
R = Read bit.
WDS = Watchdog steering bit.
BMB0–BMB4 = Watchdog multiplier bits.
RB0, RB1 = Watchdog resolution bits.
12
B2
AE = Alarm flag enable.
Y = Unused. Read/writeable without write and read bit control.
ABE = Alarm in backup mode enable.
AM1–AM4 = Alarm mask bits.
WF = Watchdog flag.
AF = Alarm flag.
0 = Reads as a 0 and cannot be changed.
BLF = Battery low flag.
____________________________________________________________________
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
RTC Write Mode
The DS3065W executes an RTC write cycle whenever
CE is inactive (high) and the CS and WE signals are
active (low) after address inputs are stable. The lateroccurring falling edge of CS or WE determines the start
of the write cycle. The write cycle is terminated by the
earlier rising edge of CS or WE. All address inputs must
be kept valid throughout the write cycle. WE must return
to the high state for a minimum recovery time (t WR)
before another cycle can be initiated. The CE and OE
control signals should be kept inactive (high) during RTC
write cycles to avoid bus contention. However, if the output drivers have been enabled (CS and OE active) then
WE disables the outputs in tODW from its falling edge.
Clock Oscillator Mode
The oscillator can be turned off to minimize battery current drain. The OSC bit is the MSB of the SECONDS
register, and must be initialized to a 0 to start the oscillator upon first power application. The OSC bit is factory set to a 1 prior to shipment. Oscillator operation and
frequency can be verified by setting the FT bit to a 1
and monitoring the IRQ/FT output for 512Hz.
Reading the Clock
When reading the RTC data, it is recommended to halt
updates to the external set of double-buffered RTC registers. This puts the external registers into a static state,
allowing the data to be read without register values
changing during the read process. Normal updates to
the internal registers continue while in this state.
External updates are halted by writing a 1 to the read
bit (R). As long as a 1 remains in the R bit, updating is
inhibited. After a halt is issued, the registers reflect the
RTC count (day, date, and time) that was current at the
moment the halt command was issued. Normal
updates to the external set of registers resume within 1
second after the R bit is set to a 0 for a minimum of
500µs. The R bit must be a 0 for a minimum of 500µs to
ensure the external registers have fully updated.
Setting the Clock
As with a clock read, it is also recommended to halt
updates prior to setting new time values. Setting the
write bit (W) to a 1 halts updates of the external RTC
registers 8h to Fh. After setting the W bit to a 1, the RTC
registers can be loaded with the desired count (day,
date, and time) in BCD format. Setting the W bit to a 0
then transfers the values written to the internal registers
and allows normal clock operation to resume.
Frequency Test Mode
The DS3065W frequency test mode uses the IRQ/FT
open-drain output. With the oscillator running, the
IRQ/FT output toggles at 512Hz when the FT bit is a 1,
the alarm-flag enable bit (AE) is a 0, and the watchdogenable bit (WDS) is a 1 or the WATCHDOG register is
written to 00h (FT • AE • (WDS + WATCHDOG)). The
IRQ/FT output and the frequency test mode can be
used to measure the actual frequency of the 32.768kHz
RTC oscillator. The FT bit is reset to a 0 on power-up.
Using the Clock Alarm
The alarm settings and control for the DS3065W reside
within RTC registers 2h–5h. The INTERRUPTS register
(6h) contains two alarm-enable bits: alarm enable (AE)
and alarm in backup enable (ABE). The AE and ABE
bits must be set as described below for the IRQ/FT output to be activated when an alarm match occurs.
The alarm can be programmed to activate on a specific
day of the month or repeat every day, hour, minute, or
second. It can also be programmed to go off while the
DS3065W is in the Data Retention Mode to serve as a
system wake-up. Alarm mask bits AM1 to AM4 control
the alarm mode (see Table 3). Configurations not listed
in the table will default to the once-per-second mode to
notify the user of an incorrect alarm setting.
____________________________________________________________________
13
DS3065W
RTC Read Mode
The DS3065W executes an RTC read cycle whenever
CE (SRAM chip enable) and WE (write enable) are
inactive (high) and CS (RTC chip select) is active (low).
The least significant 4 address inputs (A0 to A3) define
which of the 16 RTC registers is to be accessed (see
Table 2). Valid data is available to the eight data output
drivers within tACC (access time) after the last address
input signal is stable, providing that CS and OE (output
enable) access times are also satisfied. If CS and OE
access times are not satisfied, then data access must
be measured from the later occurring signal (CS or OE)
and the limiting parameter is either tCO for CS or tOEC
for OE rather than address access.
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
Table 3. Alarm Mask Bits
AM4
AM3
AM2
AM1
1
1
1
1
Once per second
1
1
1
0
When seconds match
1
1
0
0
When minutes and seconds match
1
0
0
0
When hours, minutes, and seconds match
0
0
0
0
When date, hours, minutes, and seconds match
When the RTC register values match alarm register settings, the alarm flag (AF) is set to a 1. If AE is also a 1,
the alarm condition activates the IRQ/FT output. When
CS is active, the IRQ/FT signal can be cleared by holding the FLAGS register address stable for tRC and forcing either OE or WE active (see Figure 1). The flag does
not change state until the end of the read/write cycle
and after the IRQ/FT signal has deasserted. To avoid
inadvertently clearing the IRQ/FT signal while preparing
for subsequent write/read cycles at other register
addresses, assure that tAW is met for that subsequent
address (see Figure 2).
ALARM RATE
The IRQ/FT output can also be activated during battery
backup mode. The IRQ/FT goes low if an alarm occurs
and both AE and ABE are set to 1. The AE and ABE
bits are reset to 0 during the power-up transition, but an
alarm generated during power-up will set AF to a 1.
Therefore, the AF bit can be read after system powerup to determine if an alarm was generated during the
power-up sequence. Figure 3 illustrates alarm timing
during battery backup mode and power-up states.
CE
WE OR OE
CS
tRC MAX
A0–A3
ADDRESS 0h
IRQ/FT
Figure 1. Clearing Active IRQ Waveforms
14
____________________________________________________________________
HIGH
IMPEDANCE
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
DS3065W
CE
tAS
INTENTIONAL WRITE OR
READ AT ADDRESS Xh
INADVERTENT WRITE OR READ OF
RTC FLAGS REGISTER
WILL RESET IRQ/FT
WE OR OE
CS
A0–A3
ADDRESS 0h
ADDRESS Xh
HIGH
IMPEDANCE
IRQ/FT
Figure 2. Prevent Accidental Clearing of IRQ Waveforms
VTP
VCC
ABE, AE
AF
IRQ/FT
HIGH
IMPEDANCE
HIGH
IMPEDANCE
Figure 3. Battery Back-up Mode Alarm Waveforms
____________________________________________________________________
15
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
Using the Watchdog Timer
The watchdog timer can be used to detect an out-ofcontrol processor. The user programs the watchdog
timer by setting the desired timeout delay into the
WATCHDOG register. The five high-order WATCHDOG
register bits store a binary multiplier and the two lowerorder WATCHDOG bits select the resolution, where 00
= 1/16 second, 01 = 1/4 second, 10 = 1 second, and 11
= 4 seconds. The watchdog timeout value is then
determined by multiplication of the 5-bit multiplier value
with the 2-bit resolution value. (For example: writing
00001110 (0Eh) into the WATCHDOG register = 3 x 1
second, or 3 seconds.) If the processor does not reset
the timer within the specified period, the watchdog flag
(WF) is set to a 1 and a processor interrupt is generated and stays active until either WF is read or the
WATCHDOG register is read or written.
The MSB of the WATCHDOG register is the watchdog
steering bit (WDS). When WDS is set to a 0, the watchdog activates the IRQ/FT output when the watchdog
times out. WDS should not be written to a 1, and should
be initialized to a 0 if the watchdog function is enabled.
The watchdog timer resets when the processor performs a read or write of the WATCHDOG register. The
timeout period then starts over. The watchdog timer is
disabled by writing a value of 00h to the WATCHDOG
register. The watchdog function is automatically disabled upon power-up and the WATCHDOG register is
cleared to 00h.
Power-On Default States
Upon each application of power to the device, the following register bits are automatically set to 0:
WDS = 0, BMB0–BMB4 = 0, RB0, RB1 = 0, AE = 0,
ABE = 0.
All other RTC bits are undefined.
Data-Retention Mode
The DS3065W provides full functional capability for VCC
greater than 3.0V and write-protects by 2.8V. Data is
maintained in the absence of VCC without additional
support circuitry. The NV SRAM constantly monitors
VCC. Should the supply voltage decay, the NV SRAM
automatically write-protects itself. All inputs become
don’t care, and all data outputs become high impedance. As VCC falls below approximately 2.5V (VSW), the
power-switching circuit connects the lithium energy
source to the clock and SRAM to maintain time and
retain data. During power-up, when VCC rises above
VSW, the power-switching circuit connects external VCC
to the clock and SRAM, and disconnects the lithium
16
energy source. Normal clock or SRAM operation can
resume after VCC exceeds VTP for a minimum duration
of tREC.
Battery Charging
When VCC is greater than VTP an internal regulator will
charge the battery. The UL-approved charger circuit
includes short-circuit protection and a temperature-stabilized voltage reference for on-demand charging of
the internal battery. Typical data retention expectations
greater than 2 years per charge cycle are achievable.
A maximum of 96 hours of charging time is required to
fully charge a depleted battery.
System Power Monitoring
When the external VCC supply falls below the selected
out-of-tolerance trip point, the output RST is forced
active (low). Once active, the RST is held active until
the VCC supply has fallen below that of the internal battery. On power-up, the RST output is held active until
the external supply is greater than the selected trip
point and one reset timeout period (tRPU) has elapsed.
This is sufficiently longer than tREC to ensure that the
RTC and SRAM are ready for access by the microprocessor.
Freshness Seal and Shipping
The DS3065W is shipped from Dallas Semiconductor
with the RTC oscillator disabled and the lithium battery
electrically disconnected, guaranteeing that no battery
capacity has been consumed during transit or storage.
As shipped, the lithium battery is ~60% charged, and
no pre-assembly charging operations should be
attempted.
When VCC is first applied at a level greater than VTP,
the lithium battery is enabled for backup operation. The
user is required to enable the oscillator (MSB of SECONDS register) and initialize the required RTC registers
for proper timekeeping operation. A 96 hour initial battery charge time is recommended for new system
installations.
Applications Information
Power-Supply Decoupling
To achieve the best results when using the DS3065W,
assure that all VCC and GND balls are connected and
decouple the power supply with a 0.1µF capacitor. Use
a high-quality, ceramic surface-mount capacitor if possible. Surface-mount components minimize lead inductance, which improves performance, and ceramic
capacitors tend to have adequate high-frequency
response for decoupling applications.
____________________________________________________________________
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
Using the Open-Drain IRQ/FT
and RST Outputs
The IRQ/FT and RST outputs are open drain, and therefore require pullup resistors to realize a high logic output level. Pullup resistor values between 1kΩ and 10kΩ
are typical.
Battery Charging/Lifetime
The DS3065W charges an ML battery to maximum
capacity in approximately 96 hours of operation when
VCC is greater than VTP. Once the battery is charged,
its lifetime depends primarily on the VCC duty cycle.
The DS3065W can maintain data from a single, initial
charge for up to 2 years. Once recharged, this deepdischarge cycle can be repeated for up to 20 times,
producing a worst-case service life of 40 years. More
typical duty cycles are of shorter duration, enabling the
DS3065W to be charged hundreds of times, and
extending the service life well beyond 40 years.
Recommended Cleaning
Procedures
DS3065W
Avoiding Data Bus Contention
Care should be taken to avoid simultaneous access of
the SRAM and RTC devices (see Figure 4). Any chipenable overlap violates tCCS and can result in invalid
and unpredictable behavior.
Recommended Reflow Temperature
Profile
Sn-Pb EUTECTIC
ASSEMBLY
PROFILE FEATURE
Average ramp-up rate
(TL to TP)
3°C/second max
Preheat
- Temperature min (TSmin)
- Temperature max (TSmax)
- Time (min to max) (ts)
100°C
150°C
60 to 120 seconds
TSmax to TL
- Ramp-up rate
Time maintained above:
- Temperature (TL)
- Time (tL)
183°C
60 to 150 seconds
Peak temperature (TP)
225 +0/-5°C
Time within 5°C of actual peak
temperature (TP)
10 to 30 seconds
Ramp-down rate
6°C/second max
Time 25°C to peak temperature
6 minutes max
Note: All temperatures refer to topside of the package, measured on the package body surface.
The DS3065W can be cleaned using aqueous-based
cleaning solutions. No special precautions are needed
when cleaning boards containing a DS3065W module.
Removal of the topside label violates the environmental
integrity of the package and voids the warranty of the
product.
VIH
CE
VIH
tCCS
tCCS
VIH
VIH
CS
Figure 4. SRAM/RTC Data Bus Control
____________________________________________________________________
17
Pin Configuration
TOP VIEW
1
2
3
4
5
6
7
8
9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
9
1
8
2
0
D
A16
A14
D
E
RST
A13
E
F
VCC
A12
F
G
WE
A11
G
H
OE
A10
H
J
CE
A9
J
K
DQ7
A8
K
L
DQ6
A7
L
M
DQ5
A6
M
N
DQ4
A5
N
P
DQ3
A4
P
R
DQ2
A3
R
T
DQ1
A2
T
U
DQ0
A1
U
V
GND
A0
V
W
GND
GND
W
Y
GND
GND
Y
1
2
N.C.
C
A19
A17
N.C.
A15
N.C.
C
N.C.
B
N.C.
A18
VCC
IRQ/FT
N.C.
B
N.C.
A
N.C.
GND
N.C.
GND
N.C.
A
3
4
5
6
7
8
9
1
0
1
1
1
2
1
3
1
4
1
5
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
DS3065W
CS
DS3065W
3.3V Single-Piece 8Mb Nonvolatile SRAM
with Clock
1
6
1
7
1
8
1
9
2
0
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
DS3065W BGA modules are recognized by Underwriters Laboratory (UL) under file E99151.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
is a registered trademark of Dallas Semiconductor Corporation.
Similar pages