DS1308 I2C RTC Datasheet

DS1308 Datasheet, PDF, Equivalent


Part Number

DS1308

Description

Low-Current I2C RTC

Manufacture

Maxim Integrated

Total Page 16 Pages
Datasheet
Download DS1308 Datasheet


DS1308
DS1308
Low-Current I2C RTC with 56-Byte NV RAM
General Description
The DS1308 serial real-time clock (RTC) is a low-power,
full binary-coded decimal (BCD) clock/calendar plus
56 bytes of NV RAM. Address and data are transferred
serially through an I2C interface. The clock/calendar
provides seconds, minutes, hours, day, date, month,
and year information. The end of the month date is auto-
matically 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 an AM/PM
indicator. The DS1308 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)
Benefits and Features
Compatible with Crystal ESR Up to 100kΩ Allows a
Crystal to be Optimized for Cost and Space
● Low-Power Operation Extends Battery Backup Run Time
Low Timekeeping Current of 250nA (typ)
Automatic Power-Fail Detect and Switch Circuitry
Completely Manages All Timekeeping Functions
• Real-Time Clock Counts Seconds, Minutes, Hours,
Date of the Month, Month, Day of the Week, and
Year with Leap-Year Compensation Valid Up to 2400
• External Clock Source for Synchronization Clock
Reference (e.g., 32kHz, 50Hz/60Hz Powerline,
GPS 1PPS)
56-Byte, Battery-Backed, General-Purpose RAM
with Unlimited Writes
Programmable Square-Wave Output Signal
● Simple Serial Port Interfaces with Most Microcontrollers
• I2C Serial Interface
● Industrial Temperature Range: -40ºC to +85ºC
Supports Operation in a Wide Range of Applications
Underwriters Laboratories (UL®) Recognized
Typical Operating Circuit
VCC VCC
RPU RPU RPU
CPU
SCL VCC
SDA
SQW/CLKIN
X1
X2
DS1308
VBAT
GND
Ordering Information appears at end of data sheet.
UL is a registered trademark of Underwriters Laboratories Inc.
19-6353; Rev 3; 4/15

DS1308
DS1308
Low-Current I2C RTC with 56-Byte NV RAM
Absolute Maximum Ratings
(All voltages relative to ground.)
Voltage Range on VCC or VBAT............................-0.3V to +6.0V
Voltage on Any Non-Power Pin................. -0.3V to (VCC + 0.3V)
Operating Temperature Range........................... -40NC to +85NC
Junction Temperature Maximum......................................+150NC
Storage Temperature Range............................. -55NC to +125NC
Lead Temperature (soldering, 10s).................................+300NC
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 opera-
tion 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)
FSOP
Junction-to-Ambient Thermal Resistance (BJA)......206.3NC/W
Junction-to-Case Thermal Resistance (BJC)................42NC/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
(TA = -40NC to +85NC, unless otherwise noted.) (Note 2)
PARAMETER
Operating Voltage Range
Battery Voltage
SYMBOL
VCC
VBAT
DS1308-18
DS1308-3
DS1308-33
Logic 1 Input
VIH
CONDITIONS
Logic 0 Input
VIL
MIN
1.71
2.7
3.0
1.3
0.7 x
VCC
-0.3
TYP
1.8
3.0
3.3
MAX
5.5
5.5
5.5
5.5
VCC +
0.3
0.3 x
VCC
UNITS
V
V
V
V
DC Electrical Characteristics
(VCC = VCCMIN to VCCMAX, VBAT = VBATMIN to VBATMAX, TA = -40NC to +85NC, unless otherwise noted.) (Note 2)
PARAMETER
Power-Supply Active Current
(Note 3)
SYMBOL
CONDITIONS
ICCA
fSCL = 400kHz
MIN TYP MAX
325
Power-Supply Standby Current
(Note 4)
Battery Leakage Current
Input Leakage (SCL)
I/O Leakage (SDA, SQW/CLKIN)
Output Logic 0 (SDA, SQW/
CLKIN), VOL = 0.4V
Power-Fail Trip Point
ICCS
IBATLKG
II
IIO
IOL
VPF
-33: VCC = 3.63V
-3: VCC = 3.3V
-18: VCC = 1.89V
VCC = VCCMAX
VCC R VPF
VIN = 0V to VCC
I2C bus inactive, ECLK = 1
VCC R VCCMIN
VBAT R 1.3V R VCC + 0.2V
-33
-3
-18
-100
-0.1
-0.1
3.0
250
2.70
2.45
1.45
25
2.82
2.55
1.62
125
125
100
200
+100
+0.1
+0.1
3.00
2.70
1.70
UNITS
FA
FA
nA
FA
FA
mA
FA
V
www.maximintegrated.com
Maxim Integrated 2


Features DS1308 Low-Current I2C RTC with 56-Byte NV RAM General Description The DS1308 serial real-time clock (RTC) is a low- power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV RAM. Address and data are transferred seria lly through an I2C interface. The clock /calendar provides seconds, minutes, ho urs, day, date, month, and year informa tion. The end of the month date is auto matically adjusted for months with fewe r than 31 days, including corrections f or leap year. The clock operates in eit her the 24-hour or 12-hour format with an AM/PM indicator. The DS1308 has a bu ilt-in power-sense circuit that detects power failures and automatically switc hes to the backup supply, maintaining t ime and date operation. Applications Ha ndhelds (GPS, POS Terminal) Consumer El ectronics (Set-Top Box, Digital Recordi ng, Network Appliance) Office Equipment (Fax/Printer, Copier) Medical (Glucome ter, Medicine Dispenser) Telecommunicat ions (Router, Switcher, Server) Other (Utility Meter, Vending M.
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