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DS1338U-18

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
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GENERAL DESCRIPTION
The DS1338 serial real-time clock (RTC) is a low-
power, full binary-coded decimal (BCD)
clock/calendar plus 56 bytes of NV SRAM. Address
and data are transferred serially through an I
2
C
interface. The clock/calendar provides seconds,
minutes, hours, day, date, month, and year
information. The end of the month date is
automatically adjusted for months with fewer than 31
days, including corrections for leap year. The clock
operates in either the 24-hour or 12-hour format with
AM/PM indicator. The DS1338 has a built-in power-
sense circuit that detects power failures and
automatically switches to the backup supply,
maintaining time and date operation
APPLICATIONS
Handhelds (GPS, POS Terminal)
Consumer Electronics (Set-Top Box, Digital
Recording, Network Appliance)
Office Equipment (Fax/Printer, Copier)
Medical (Glucometer, Medicine Dispenser)
Telecommunications (Router, Switcher, Server)
Other (Utility Meter, Vending Machine, Thermostat,
Modem)
TYPICAL OPERATING CIRCUIT
FEATURES
RTC Counts Seconds, Minutes, Hours, Date
of the Month, Month, Day of the Week, and
Year with Leap-Year Compensation Valid Up
to 2100
Available in a Surface-Mount Package with an
Integrated Crystal (DS1338C)
56-Byte Battery-Backed General-Purpose
RAM with Unlimited Writes
I
2
C Serial Interface
Programmable Square-Wave Output Signal
Automatic Power-Fail Detect and Switch
Circuitry
-40°C to +85°C Operating Temperature Range
Underwriters Laboratories (UL) Recognized
ORDERING INFORMATION
PART TEMP RANGE PIN-PACKAGE TOP MARK†
DS1338Z-18+
-40°C to +85°C
8 SO (0.150″)
DS1338-18
DS1338Z-3+
-40°C to +85°C
8 SO (0.150
″
)
DS1338-3
DS1338Z-33+
-40°C to +85°C
8 SO (0.150″)
DS133833
DS1338U-18+ -40°C to +85°C
8 µSOP
1338
rr-18
DS1338U-3+ -40°C to +85°C
8 µSOP
1338
rr-3
DS1338U-33+ -40°C to +85°C
8 µSOP
1338
rr-33
DS1338C-18# -40°C to +85°C
16 SO (0.300″)
DS1338C-18
DS1338C-3#
-40°C to +85°C
16 SO (0.300″)
DS1338C-3
DS1338C-33#
-40°C to +85°C
16 SO (0.300″)
DS1338C-33
rr = second line, revision level
+ Denotes a lead(Pb)-free/RoHS-compliant device.
# Denotes a RoHS-compliant device that may include lead that is
exempt under the RoHS requirements. The lead finish is JESD97
category e3, and is compatible with both lead-based and lead-free
soldering processes.
† A “+” anywhere on the top mark denotes a lead-free device. A “#”
denotes a RoHS-compliant device.
Pin Configurations appear at end of data sheet.
DS1338
CPU
V
V
CC
V
SDA
SCL
GND
X2
X1
V
R
PU
R
PU
CRYSTAL
SQW /OUT
V
BAT
i
R
PU
= t
r
/C
b
DS1338
I
2
C RTC with 56-
Byte NV RAM
19-6019; Rev 3/12
DS1338 I
2
C RTC with 56-Byte NV RAM
2 of 16
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground………………………………………………………..……..-0.3V to +6.0V
Operating Temperature Range…………………………………………………………………………..……-40°C to +85°C
Storage Temperature Range………………………………………………………………………………...-55°C to +125°C
Lead Temperature (soldering, 10s) ……….………………………………………………………………………. +260°C
Soldering Temperature (reflow) ……………………………………………………………………………………. +260°C
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
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C, unless
otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage V
CC
DS1338-18
1.71
1.8
5.5
V
DS1338-3
2.7
3.0
5.5
DS1338-33
3.0
3.3
5.5
Logic 1 V
IH
(Note 2)
0.7 x
V
CC
V
CC
+
0.3
V
Logic 0 V
IL
(Note 2) -0.3
+0.3 x
V
CC
V
Power-Fail Voltage V
PF
DS1338-18
1.51
1.62
1.71
V
DS1338-3
2.45
2.59
2.70
DS1338-33
2.70
2.82
2.97
V
BAT
Input Voltage V
BAT
(Note 2) 1.3 3.0 3.7 V
DC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
CC
= TYP,
T
A
= +25°C, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Leakage I
LI
(Note 3) 1
µA
I/O Leakage I
LO
(Note 4) 1
µA
SDA Logic 0 Output I
OLSDA
V
CC
> 2V; V
OL
= 0.4V
3.0
mA
V
CC
< 2V; V
OL
= 0.2 x V
CC
3.0
SQW/OUT Logic 0 Output I
OLSQW
V
CC
> 2V; V
OL
= 0.4V
3.0
mA
1.71V < V
CC
< 2V;
V
OL
= 0.2 x V
CC
3.0
1.3V < V
CC
< 1.71V;
V
OL
= 0.2 x V
CC
250
µA
Active Supply Current
(Note 5)
I
CCA
DS1338-18: V
CC
= 1.89V
75
150
µA
DS1338-3: V
CC
= 3.30V
110
200
DS1338-33
V
CC
= 3.63V
120
200
V
CC
= 5.5V
325
Standby Current (Note 6) I
CCS
DS1338-18: V
CC
= 1.89V
60
100
µA
DS1338-3: V
CC
= 3.30V
80
125
DS1338-33
V
CC
= 3.63V
85
125
V
CC
= 5.5V
200
V
BAT
Leakage Current
(V
CC
Active)
I
BATLKG
25 100 nA
DS1338 I
2
C RTC with 56-Byte NV RAM
3 of 16
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 0V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
BAT
= 3.0V, T
A
= +25°C, unless
otherwise noted.) (Note 1)
PARAMETER SYMBOL MIN TYP MAX UNITS
V
BAT
Current (OSC ON); V
BAT
= 3.7V, SQW/OUT OFF (Note 7) I
BATOSC1
800 1200 nA
V
BAT
Current (OSC ON); V
BAT
= 3.7V, SQW/OUT ON (32kHz)
(Note 7)
I
BATOSC2
1025 1400 nA
V
BAT
Data-Retention Current (Osc Off); V
BAT
= 3.7V (Note 7) I
BATDAT
10 100 nA
AC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C) (Note 1)
PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS
SCL Clock Frequency f
SCL
Fast mode
100
400
kHz
Standard mode 0 100
Bus Free Time Between STOP
and START Condition
t
BUF
Fast mode 1.3
µs
Standard mode 4.7
Hold Time (Repeated) START
Condition (Note 8)
t
HD:STA
Fast mode 0.6
µs
Standard mode 4.0
LOW Period of SCL Clock t
LOW
Fast mode 1.3
µs
Standard mode 4.7
HIGH Period of SCL Clock t
HIGH
Fast mode 0.6
µs
Standard mode 4.0
Setup Time for Repeated
START Condition
t
SU:STA
Fast mode 0.6
µs
Standard mode 4.7
Data Hold Time (Notes 9, 10) t
HD:DAT
Fast mode 0 0.9
µs
Standard mode 0
Data Setup Time (Note 11) t
SU:DAT
Fast mode 100
ns
Standard mode 250
Rise Time of Both SDA and
SCL Signals (Note 12)
t
R
Fast mode 20 + 0.1C
B
300
ns
Standard mode 20 + 0.1C
B
1000
Fall Time of Both SDA and
SCL Signals (Note 12)
t
F
Fast mode 20 + 0.1C
B
300
ns
Standard mode 20 + 0.1C
B
300
Setup Time for STOP
Condition
t
SU:STO
Fast mode
0.6
µs
Standard mode 4.0
Capacitive Load for Each Bus
Line
C
B
(Note 12) 400 pF
I/O Capacitance (SDA, SCL) C
I/O
(Note 13) 10 pF
Oscillator Stop Flag (OSF)
Delay
t
OSF
(Note 14) 100
ms
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

DS1338U-18

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IC RTC CLK/CALENDAR I2C 8-USOP
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