DS1501/DS1511
Y2K-Compliant Watchdog
Real-Time Clocks
www.maxim-ic.com
GENERAL DESCRIPTION
The DS1501/DS1511 are full-function, year 2000-
compliant real-time clock/calendars (RTCs) with an
RTC alarm, watchdog timer, power-on reset, battery
monitors, 256 bytes NV SRAM, and a 32.768kHz
output. User access to all registers within the
DS1501/DS1511 is accomplished with a byte-wide
interface, as shown in Figure 8. The RTC registers
contain century, year, month, date, day, hours,
minutes, and seconds data in 24-hour binary-coded
decimal (BCD) format. Corrections for day of month
and leap year are made automatically.
FEATURES
§
BCD-Coded Century, Year, Month, Date, Day,
Hours, Minutes, and Seconds with Automatic
Leap-Year Compensation Valid Up to the Year
2100
Programmable Watchdog Timer and RTC Alarm
Century Register; Y2K-Compliant RTC
+3.3 or +5V Operation
Precision Power-On Reset
Power-Control Circuitry Support System Power-
On from Date/Day/Time Alarm or Key
Closure/Modem-Detect Signal
256 Bytes Battery-Backed NV SRAM
Auxiliary Battery Input
Accuracy of DS1511 Better than ±1
Minute/Month at +25°C
Day-of-Week/Date Alarm Register
Crystal Select Bit Allow RTC to Operate with 6pF
or 12.6pF Crystal
Battery Voltage-Level Indicator Flags
Available as Chip (DS1501) or Stand-Alone
Module with Embedded Battery and Crystal
(DS1511)
UL Recognized
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APPLICATIONS
Remote Systems
Battery-Backed Systems
Telecom Switches
Office Equipment
Consumer Electronics
ORDERING INFORMATION
PART
DS1501YN
DS1501YEN
DS1501YSN
DS1501WN
DS1501WEN
DS1501WSN
DS1511Y
DS1511W
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
28 DIP (600 mil)
28 TSOP
28 SO (330 mil)
28 DIP (600 mil)
28 TSOP
28 SO (330 mil)
28 Module (720 mil)
28 Module (720 mil)
PIN CONFIGURATION
TOP VIEW
Selector Guide appears at end of data sheet.
Typical Operating Circuits appears at end of data sheet.
PWR
X1
X2
RST
IRQ
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
1
28
2
27
3
26
4
25
Dallas
5
Semiconductor
24
6
DS1501
23
22
7
21
8
20
9
19
10
18
11
17
12
16
13
15
14
V
CC
WE
V
BAUX
V
BAT
KS
SQW
OE
GND
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DIP, SO
Pin Configurations are continued at end of data sheet.
Note:
Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here:
www.maxim-ic.com/errata.
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REV: 031704
DS1501/DS1511 Y2KC Watchdog Real-Time Clocks
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground……………………………………………………..……....-0.5V to +6.0V
Operating Temperature Range (Module)…………………………………………………………..………....0°C to +70°C
Operating Temperature Range, DS1501
………………………………………………..
-40°C to +85°C (Note 1)
Operating Temperature Range, DS1511……………………………………………………………….……..0°C to +70°C
Storage Temperature Range, DS1501
…………………...…………………………………....
-55°C to +125°C
Storage Temperature Range, DS1511………………………………………………………………….…..-40°C to +70°C
Soldering Temperature (DIP, Module)….………………….+260°C Lead Temperature for 10 seconds (max) (Note 2)
Soldering Temperature (SO, TSOP)
…….……………..
See IPC/JEDEC J-STD-020A for Surface-Mount Devices
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 the absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED DC OPERATING CONDITIONS
(V
CC
= 3.3V or 5V ±10%, T
A
= 0°C to +70°C; V
CC
= 3.3V or 5V ±10%, T
A
= -40°C to +85°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
5V (Y)
4.5
5.0
Power Supply Voltage (Note 3)
V
CC
3.3V (W)
3.0
3.3
Y
2.2
Logic 1 Voltage All Inputs (Note 3)
V
IH
W
2.0
Pullup Voltage,
IRQ
,
PWR
, and
V
PU
RST
Outputs (Note 3)
Y
-0.3
Logic 0 Voltage All Inputs (Note 3)
V
IL
W
-0.3
Battery Voltage (Note 3)
Auxiliary Battery Voltage (Note 3)
V
BAT
V
BAUX
Y
W
2.5
2.5
2.5
3.0
3.0
3.0
MAX
5.5
3.6
V
CC
+ 0.3
V
CC
+ 0.3
5.5
+0.8
+0.6
3.7
5.3
3.7
UNITS
V
V
V
V
V
V
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 3.3V or 5V ±10%, T
A
= 0°C to +70°C; V
CC
= 3.3V or 5V ±10%, T
A
= -40°C to +85°C.)
PARAMETER
SYMBOL CONDITIONS
MIN
TYP
Y
Active Supply Current (Note 4)
I
CC
W
Y
I
CC1
TTL Standby Current (
CE
= V
IH
)
W
CMOS Standby Current
Y
I
CC2
(
CE =
V
CC
- 0.2V)
W
Input Leakage Current (Any Input)
Output Leakage Current (Any Output)
Output Logic 1 Voltage
(I
OUT
= -1.0mA)
Output Logic 0 Voltage (I
OUT
= 2.1mA,
DQ0–7; I
OUT
= 5.0mA,
IRQ
, I
OUT
=
7.0mA,
PWR
and
RST
)
Battery Low, Flag Trip Point (Note 2)
Power-Fail Voltage (Note 2)
Battery Switchover Voltage (Notes 3, 6)
Battery Leakage Current
I
IL
I
OL
V
OH
V
OL1
V
OL2
V
BLF
V
PF
V
SO
I
LKG
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(Note 3)
(Note 3)
(Notes 3, 5)
Y
W
Y
W
2.0
1.9
4.20
2.75
V
BAT,
V
BAUX,
or V
PF
100
4.50
2.97
-1
-1
2.4
0.4
0.4
MAX
15
10
5
4
5
4
+1
+1
UNITS
mA
mA
mA
mA
mA
V
V
V
V
V
V
nA
DS1501/DS1511 Y2KC Watchdog Real-Time Clocks
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 0V; T
A
= 0°C to +70°C; V
CC
= 0V, T
A
= -40°C to +85°C.)
PARAMETER
SYMBOL
CONDITIONS
I
BAT1
(Note 7)
Battery Current, BB32 = 0,
EOSC
= 0
I
BAT2
(Note 7)
Battery Current, BB32 = 0,
EOSC
= 1
I
BAUX
(Note 7)
V
BAUX
Current BB32 = 1, SQW Open
MIN
TYP
0.27
0.01
2
MAX
1.0
0.1
UNITS
mA
mA
mA
CRYSTAL SPECIFICATIONS*
PARAMETER
Nominal Frequency
Series Resistance
Load Capacitance
SYMBOL
f
O
ESR
C
L
CONDITIONS
MIN
TYP
32.768
6
MAX
45
UNITS
kHz
kW
pF
*The crystal, traces, and crystal input pins should be isolated from RF generating signals. Refer to
Application Note 58: Crystal Considerations
for Dallas Real-Time Clocks
for additional specifications.
AC OPERATING CHARACTERISTICS
(V
CC
= 5V ±10%, T
A
= 0°C to +70°C; V
CC
= 5V ±10%, T
A
= -40°C to +85°C.)
PARAMETER
SYMBOL
CONDITIONS
Read Cycle Time
t
RC
Address Access Time
t
AA
t
CEL
(Note 8)
CE
to DQ Low-Z
t
CEA
CE
Access Time
t
CEZ
(Note 8)
CE
Data-Off Time
t
OEL
(Note 8)
OE
to DQ Low-Z (0°C to +85°C)
t
OEL
(Note 8)
OE
to DQ Low-Z (-40°C to 0°C)
t
OEA
OE
Access Time
t
OEZ
(Note 8)
OE
Data-Off Time
Output Hold from Address
t
OH
Write Cycle Time
t
WC
Address Setup Time
t
AS
t
WEW
WE
Pulse Width
t
CEW
CE
Pulse Width
Data Setup Time
t
DS
Data Hold Time
t
DH
Address Hold Time
t
AH
t
WEZ
(Note 8)
WE
Data-Off Time
Write Recovery Time
t
WR
PW
HIGH
Pulse Width,
OE
,
WE
, or
CE
High
PW
LOW
Pulse Width,
OE
,
WE
, or
CE
Low
MIN
70
5
70
25
5
2
35
25
5
70
0
50
55
30
5
0
25
15
20
70
TYP
MAX
70
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
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DS1501/DS1511 Y2KC Watchdog Real-Time Clocks
AC OPERATING CHARACTERISTICS
(V
CC
= 3.3V ±10%,
T
A
= 0°C to +70°C;
V
CC
= 3.3V ±10%,
T
A
= -40°C to +85°C.)
PARAMETER
Read Cycle Time
Address Access Time
CE
to DQ Low-Z
CE
Access Time
CE
Data Off Time
OE
to DQ Low-Z (0°C to +85°C)
OE
to DQ Low-Z (-40°C to 0°C)
OE
Access Time
OE
Data-Off Time
Output Hold from Address
Write Cycle Time
Address Setup Time
WE
Pulse Width
CE
Pulse Width
Data Setup Time
Data Hold Time
Address Hold Time
WE
Data-Off Time
Write Recovery Time
Pulse Width,
OE
,
WE
, or
CE
High
Pulse Width,
OE
,
WE
, or
CE
Low
SYMBOL
t
RC
t
AA
t
CEL
t
CEA
t
CEZ
t
OEL
t
OEL
t
OEA
t
OEZ
t
OH
t
WC
t
AS
t
WEW
t
CEW
t
DS
t
DH
t
AH
t
WEZ
t
WR
PW
HIGH
PW
LOW
CONDITIONS
MIN
120
5
120
40
5
2
100
35
5
120
0
100
110
80
5
5
(Note 8)
15
40
100
40
TYP
MAX
120
(Note 8)
(Note 8)
(Note 8)
(Note 8)
(Note 8)
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Figure 1. Read Cycle Timing
t
RC
A0–A4
t
AA
CE
t
CEA
t
CEZ
t
OH
t
CEL
OE
t
OEA
t
OEZ
t
OEL
DQ0-DQ7
VALID
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DS1501/DS1511 Y2KC Watchdog Real-Time Clocks
Figure 2. Write Cycle Timing, Write-Enable Controlled
t
WC
A0–A4
VALID
VALID
t
AS
t
AH
CE
t
AS
t
WEW
t
WR
WE
t
WEZ
t
DS
t
DH
DQ0–DQ7
DATA OUTPUT
DATA INPUT
DATA INPUT
Figure 3. Write Cycle Timing, Chip-Enable Controlled
t
W C
A0-A4
VALID
VALID
t
AS
t
CEW
t
AH
CE
t
AS
t
W R
WE
t
DS
t
DH
DQ0-DQ7
DATA INPUT
DATA INPUT
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