The DS1343/DS1344 low-current real-time clocks (RTCs)
are timekeeping devices that provide an extremely low
standby current, permitting longer life from a backup
supply source. The devices also support high-ESR
crystals, broadening the pool of usable crystals for the
devices. The clock/calendar provides seconds, minutes,
hours, day, date, month, and year information. The date
at the end of the month is automatically adjusted for
months with fewer than 31 days, including corrections
for leap year. The clock operates in either 24-hour or
12-hour format with an
AM/PM
indicator.
Address and data are transferred serially through an
SPI or 3-wire interface. Two programmable time-of-day
alarms are provided. Each alarm can generate an inter-
rupt on a combination of seconds, minutes, hours, and
day. Don’t-care states can be inserted into one or more
fields if it is desired for them to be ignored for the alarm
condition. The time-of-day alarms can be programmed
to assert two different interrupt outputs, or they can be
combined to assert one common interrupt output. Both
interrupt outputs operate when the device is powered by
either V
CC
or V
BAT
.
The devices are available in a lead-free/RoHS-compliant,
20-pin TSSOP or 14-pin TDFN package, and support a
-40°C to +85°C extended industrial temperature range.
Features
S
Low Timekeeping Current of 250nA (typ)
S
Compatible with Crystal ESR Up to 100kI
S
Versions Available to Support Either 6pF or
12.5pF Crystals
S
RTC Counts Seconds, Minutes, Hours, Day, Date,
Month, and Year with Leap Year Compensation
Valid Through 2099
S
Power-Fail and Switch Circuitry
S
Three Operating Voltages
1.8V ±5%
3.0V±10%
3.3V ±10%
S
Trickle-Charge Capability
S
Maintain Time Down to 1.15V (typ)
S
Support Motorola SPI Modes 1 and 3, or Standard
3-Wire Interface
S
Burst Mode for Reading/Writing Successive
Addresses in Clock/RAM
S
96-Byte Battery-Backed NV RAM for Data Storage
S
Two Time-of-Day Alarms with Two Interrupt
Outputs
S
Industrial Temperature Range
S
20-Pin TSSOP or 14-Pin TDFN Package
S
Underwriters Laboratories (UL) Recognized
Applications
Medical
Handheld Devices
Telematics
Embedded Timestamping
Typical Operating Circuit
V
CC
R
PU
V
CC
INT0
PF
INT1
CE
SCLK
SDI
SDO
X1
DS1343
DS1344
INT
RST
P
Ordering Information
appears at end of data sheet.
3-WIRE
PORT
X2
V
BAT
SERMODE GND
NOTE:
SHOWN IN 3-WIRE I/O CONFIGURATION.
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-5801; Rev 2; 10/14
DS1343/DS1344
Low-Current SPI/3-Wire RTCs
ABSOLUTE MAXIMUM RATINGS
Voltage Range on V
CC
or V
BAT
Relative to Ground............................................-0.3V to +6.0V
Voltage Range on Any Nonpower Pin
Relative to Ground................................ -0.3V to (V
CC
+ 0.3V)
Operating Temperature Range .......................... -40NC to +85NC
Junction Temperature Maximum.....................................+150NC
Storage Temperature Range............................ -55NC to +125NC
Lead Temperature (soldering, 10s) ................................+260NC
Soldering Temperature (reflow) ......................................+260NC
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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
TSSOP
Junction-to-Ambient Thermal Resistance (B
JA
) ..........91NC/W
Junction-to-Case Thermal Resistance (B
JC
) ...............20NC/W
TDFN
Junction-to-Ambient Thermal Resistance (B
JA
) ..........54NC/W
Junction-to-Case Thermal Resistance (B
JC
) .................8NC/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
RECOMMENDED OPERATING CONDITIONS
(T
A
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
Operating Voltage Range
Minimum Timekeeping Voltage
Backup Voltage
Logic 1 Input
Logic 0 Input
SYMBOL
DS134_-18
V
CC
V
BAT
T
MIN
V
BAT
V
IH
V
IL
DS134_-3
DS134_-33
T
A
= +25NC
1.3
0.7 x
V
CC
-0.3
CONDITIONS
MIN
1.71
2.7
3.0
TYP
1.8
3.0
3.3
1.15
MAX
5.5
5.5
5.5
1.3
5.5
V
CC
+
0.3
0.3 x
V
CC
V
V
V
V
V
UNITS
DC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to +5.5V, V
BAT
= +1.3V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 2, 3)
PARAMETER
Power-Supply Active Current
SYMBOL
I
CCA
CONDITIONS
-3 or -33: f
SCLK
= 4MHz (Note 4)
-33
Power-Supply Standby Current
(Note 5)
I
CCS
-3
-18
Backup Leakage Current
Backup Current (Oscillator Off)
Backup Current
(Note 6)
2
MIN
TYP
MAX
400
120
160
130
175
120
200
UNITS
FA
V
CC
= 3.63V
V
CC
= V
CC(MAX)
V
CC
= 3.3V
V
CC
= V
CC(MAX)
V
CC
= 1.89V
V
CC
= V
CC(MAX)
-100
+25
250
FA
I
BATLKG
I
BAT
DS1343
I
BAT1
DS1344
V
CC
> V
PF
T
A
= +25NC, V
CC
= 0V,
EOSC
= 1
V
BAT
= 3V
V
BAT
= V
BAT(MAX)
V
BAT
= 3V
V
BAT
= V
BAT(MAX)
+100
100
500
nA
nA
350
600
nA
Maxim Integrated
DS1343/DS1344
Low-Current SPI/3-Wire RTCs
DC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= V
CC(MIN)
to +5.5V, V
BAT
= +1.3V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 2, 3)
PARAMETER
Backup Current
(Note 7)
DS1343
I
BAT2
DS1344
I
I
I
O
I
OH
SYMBOL
V
BAT
= 3V
V
BAT
= V
BAT(MAX)
V
BAT
= 3V
V
BAT
= V
BAT(MAX)
V
IN
= 0V to V
CC
CE = V
IL
, no alarms
-3 or -33: V
OH
= 2.4V
-18: V
OH
= 1V
-3 or -33: V
OL
= 0.4V
Output Logic 0
(INT0,
INT1, PF,
SDO)
I
OL
-18: V
OL
= 0.4V
V
BAT
R
1.3V
R
V
CC
+ 0.2V, V
OL
=
0.2V
(Note 8)
-18
Power-Fail Trip Point
V
PF
-3
-33
Switchover Voltage
V
SW
R1
Trickle-Charger Resistors
R2
R3
V
BAT
> V
PF
V
BAT
< V
PF
-0.1
-0.1
-1
-0.5
3.0
2.0
0.25
1.51
2.45
2.70
1.6
2.6
2.88
V
PF
V
BAT
> V
CC
1
2
4
kI
1.71
2.70
3.0
V
V
mA
400
700
+0.1
+0.1
FA
FA
mA
CONDITIONS
MIN
TYP
300
600
nA
MAX
UNITS
Input Leakage (CE, SERMODE,
SCLK, SDI)
Output Leakage
(INT0,
INT1, PF,
SDO)
Output Logic 1 (PF, SDO)
AC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 2, 3)
PARAMETER
SCLK Frequency
Data to SCLK Setup
SCLK to Data Hold
SCLK to Data Delay
SCLK Low Time
SCLK High Time
SYMBOL
f
SCLK
t
DC
t
CDH
t
CDD
t
CL
t
CH
-18
-3 or -33
-18
-3 or -33
-18
-3 or -33
400
110
400
110
-18
-3 or -33
CONDITIONS
MIN
DC
DC
30
30
240
80
TYP
MAX
1
4
UNITS
MHz
ns
ns
ns
ns
ns
Maxim Integrated
3
DS1343/DS1344
Low-Current SPI/3-Wire RTCs
AC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 2, 3)
SCLK Rise and Fall
CE to SCLK Setup
SCLK to CE Hold
CE Inactive Time
CE to Output High-Z
Oscillator Stop Flag (OSF) Delay
t
R,
t
F
t
CC
t
CCH
t
CWH
t
CDZ
t
OSF
(Note 9)
25
-18
-3 or -33
400
100
500
400
80
100
200
ns
ns
ns
ns
ns
ms
POWER-UP/DOWN CHARACTERISTICS
(T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
Recovery at Power-Up
V
CC
Fall Time (V
PF
to 0V)
V
CC
Rise Time (0V to V
PF
)
SYMBOL
t
REC
t
VCCF
t
VCCR
150
0
CONDITIONS
MIN
TYP
20
MAX
40
UNITS
ms
Fs
Fs
CAPACITANCE
(T
A
= +25°C, unless otherwise noted.)
PARAMETER
Input Capacitance
Output Capacitance
SYMBOL
C
I
C
O
(Note 10)
(Note 10)
CONDITIONS
MIN
TYP
10
15
MAX
UNITS
pF
pF
CRYSTAL PARAMETERS
PARAMETER
Nominal Frequency
Series Resistance
Load Capacitance
Note
Note
Note
Note
Note
Note
Note
Note
Note
SYMBOL
f
O
ESR
C
L
DS1343
DS1344
6
12.5
CONDITIONS
MIN
TYP
32.768
100
MAX
UNITS
kHz
kI
pF
2:
Voltage referenced to ground.
3:
Limits at T
A
= -40°C are guaranteed by design and not production tested.
4:
CE = V
CC
, V
SCLK
= V
CC
to GND, I
OUT
= 0mA, trickle charger disabled.
5:
CE = GND, I
OUT
= 0mA,
EOSC
= EGFIL = DOSF = 0, trickle charger disabled.
6:
V
CC
= 0V, EGFIL = 0, DOSF = 1.
7:
V
CC
= 0V, EGFIL = 1, DOSF = 0.
8:
Applies to
INT0
and
INT1.
9:
The parameter t
OSF
is the period of time the oscillator must be stopped for the OSF flag to be set.
10:
Guaranteed by design; not 100% production tested.
4
Maxim Integrated
DS1343/DS1344
Low-Current SPI/3-Wire RTCs
SPI Write Timing
t
CWH
CE
t
CC
t
CL
SCLK*
t
CDH
t
CH
t
F
t
R
t
CCH
t
DC
t
CDH
SDI
R/W = 1
A6
A0
D7
D0
WRITE ADDRESS BYTE
*SCLK CAN BE EITHER POLARITY. TIMING SHOWN FOR CPOL = 1.
SERMODE = V
CC
.
WRITE DATA BYTE
SPI Read Timing
t
CWH
CE
t
CC
t
CL
SCLK*
t
CDH
t
DC
SDI
t
CH
t
CDD
t
CDZ
R/W = 0
A6
A0
SDO
D7
D0
WRITE ADDRESS BYTE
*SCLK CAN BE EITHER POLARITY. TIMING SHOWN FOR CPOL = 1.
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