DS1500
Y2K Watchdog RTC with
Nonvolatile Control
www.maxim-ic.com
GENERAL DESCRIPTION
The DS1500 is a full-function, year 2000-compliant
real-time clock/calendar (RTC) with an alarm,
watchdog timer, power-on reset, battery monitors,
256 bytes of on-board nonvolatile (NV) SRAM, NV
control for backing up an external SRAM, and a
32.768kHz output. User access to all registers within
the DS1500 is accomplished with a byte-wide
interface, as shown in Figure 7. 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
Automatic Battery Backup and Write Protection
to External SRAM
+5V Operation
Precision Power-On Reset
Power-Control Circuitry Supports System Power-
On from Date/Day/Time Alarm or Key Closure
256 Bytes User NV RAM
Auxiliary Battery Input
Accuracy Better than ±1 Minute/Month at +25°C
Day-of-Week/Date Alarm Register
Battery Voltage-Level Indicator Flags
Industrial Temperature Range: -40°C to +85°C
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APPLICATIONS
Remote Systems
Battery-Backed Systems
Telecom Switches
Office Equipment
Consumer Electronics
ORDERING INFORMATION
PART
DS1500YEN
DS1500WEN
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
32 TSOP
32 TSOP
PIN CONFIGURATION
TOP VIEW
Selector Guide appears at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
Dallas
Semiconductor
DS1500
TSOP
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: 030603
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground
Operating Temperature Range
Storage Temperature Range
Soldering Temperature
-0.5V to +6.0V
-40°C to +85°C (Note 1)
-55°C to +125°C
See IPC/JEDEC J-STD-020A Specification
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.
RECOMMENDED DC OPERATING CONDITIONS
(T
A
= -40°C to +85°C)
PARAMETER
Power Supply Voltage (Note 2)
Logic 1 Voltage All Inputs (Note 2)
Pullup Voltage,
IRQ
,
PWR
, and
RST
Outputs
Logic 0 Voltage All Inputs (Note 2)
Battery Voltage (Note 2)
Auxiliary Battery Voltage (Note 2)
SYMBOL
CONDITIONS
5V (Y)
3.3V (W)
Y
W
(Note 2)
Y
W
Y
W
MIN
4.5
3.0
2.2
2.0
-0.3
-0.3
2.5
2.5
2.5
3.0
3.0
3.0
TYP
5.0
3.3
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
V
CC
V
IH
V
PU
V
IL
V
BAT
V
BAUX
DC ELECTRICAL CHARACTERISTICS
(V
CCMIN
< V
CCI
< V
CCMAX
, T
A
= -40°C to +85°C.)
PARAMETER
Active Supply Current (Note 3)
TTL Standby Current (CS = V
IH
)
CMOS Standby Current
(CS
³
V
CCI
- 0.2V)
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,
CEO
I
OUT
= 5.0mA,
IRQ
,
I
OUT
= 7.0mA
PWR
, and
RST
)
Battery Low, Flag Trip Point (Note 2)
Output Voltage (I
CCO1
= 85mA ) (Note 5)
Power-Fail Voltage (Note 2)
Battery Switchover Voltage
Output Voltage (I
CCO2
= 50µA)
Battery Leakage Current
SYMBOL
I
CC
I
CC1
I
CC2
I
IL
I
OL
V
OH
V
OL1
V
OL2
V
BLF
V
CCO1
V
PF
V
SO
V
CCO2
I
LKG
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(Note 2)
(Note 2)
(Notes 2, 4)
Y
W
Y
W
Y
W
(Notes 2, 6)
(Note 7)
V
BAT
-
0.3
10
100
2.0
1.9
V
CCI
-
0.3
4.20
2.75
V
BAT,
V
BAUX,
or V
PF
CONDITIONS
Y
W
Y
W
Y
W
MIN
TYP
MAX
15
10
5
4
5
4
+1
+1
0.4
0.4
UNITS
mA
mA
mA
mA
mA
V
V
V
V
V
4.50
2.97
V
V
V
nA
-1
-1
2.4
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 0V, T
A
= -40°C to +85°C.)
PARAMETER
Battery Current, BB32 = 0,
EOSC
= 0
Battery Current, BB32 = 0,
EOSC
= 1
V
BAUX
Current BB32 = 1, SQW Open
SYMBOL
I
BAT1
I
BAT2
I
BAUX
CONDITIONS
(Notes 8, 9)
(Notes 8, 9)
(Notes 8, 9)
MIN
TYP
0.27
0.01
2
MAX
1.0
0.1
UNITS
µA
µA
µA
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
kΩ
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
CCI
= 5.0V
±10%,
T
A
= -40°C to +85°C.)
PARAMETER
Read Cycle Time
Address Access Time
CS
to DQ Low-Z
CS
Access Time
CS
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
CS
Pulse Width
Data Setup Time
Data Hold Time
Address Hold Time
WE
Data Off Time
Write Recovery Time
CEI
to
CEO
Propagation Delay
Pulse Width,
OE
,
WE
, or
CS
High
Pulse Width,
OE
,
WE
, or
CS
Low
SYMBOL
t
RC
t
AA
t
CSL
t
CSA
t
CSZ
t
OEL
t
OEL
t
OEA
t
OEZ
t
OH
t
WC
t
AS
t
WEW
t
CSW
t
DS
t
DH
t
AH
t
WEZ
t
WR
t
CEPD
PW
HIGH
PW
LOW
CONDITIONS
MIN
70
5
70
25
5
2
35
25
5
70
0
50
55
30
5
0
(Note 10)
15
10
20
70
25
TYP
MAX
70
(Note 10)
(Note 10)
(Note 10)
(Note 10)
(Note 10)
UNITS
ns
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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DS1500 Y2KC Watchdog RTC with Nonvolatile Control
AC OPERATING CHARACTERISTICS (continued)
(V
CCI
= 3.3V
±10%,
T
A
= -40°C to +85°C.)
PARAMETER
Read Cycle Time
Address Access Time
CS
to DQ Low-Z
CS
Access Time
CS
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
CS
Pulse Width
Data Setup Time
Data Hold Time
Address Hold Time
WE
Data Off Time
Write Recovery Time
CEI
to
CEO
Propagation Delay
Pulse Width,
OE
,
WE
, or
CS
High
Pulse Width,
OE
,
WE
, or
CS
Low
SYMBOL
t
RC
t
AA
t
CSL
t
CSA
t
CSZ
t
OEL
t
OEL
t
OEA
t
OEZ
t
OH
t
WC
t
AS
t
WEW
t
CSW
t
DS
t
DH
t
AH
t
WEZ
t
WR
t
CEPD
PW
HIGH
PW
LOW
CONDITIONS
MIN
120
5
120
40
5
2
100
35
5
120
0
100
110
80
5
0
(Note 10)
15
10
40
100
40
TYP
MAX
120
(Note 10)
(Note 10)
(Note 10)
(Note 10)
(Note 10)
UNITS
ns
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
CS
t
C SA
t
C SZ
t
OH
t
CSL
OE
t
OEA
t
O EZ
t
OEL
DQ 0-DQ 7
VALID
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DS1500 Y2KC Watchdog RTC with Nonvolatile Control
Figure 2. Write Cycle Timing, Write-Enable-Controlled
t
W C
A0-A4
VALID
VALID
t
AS
t
AH
CS
t
AS
t
W EW
t
W R
WE
t
W EZ
t
DS
t
D H
DQ0-DQ7
DATA OUT PUT
D ATA INPUT
DATA INPUT
Figure 3. Write Cycle Timing, Chip-Select-Controlled
t
W C
A0-A4
VALID
VALID
t
AS
t
CSW
t
AH
CS
t
AS
t
W R
WE
t
D S
t
DH
DQ0-DQ7
D ATA INPUT
DATA IN PUT
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