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FEATURES
Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year with Leap-Year Compensation Valid Up to 2100 96-Byte, Battery-Backed NV RAM for Data Storage Two Time-of-Day Alarms, Programmable on Combination of Seconds, Minutes, Hours, and Day of the Week 1Hz and 32.768kHz Clock Outputs Supports Motorola SPI ™ (Serial Peripheral Interface) Modes 1 and 3 or Standard 3-Wire Interface Burst Mode for Reading/Writing Successive Addresses in Clock/RAM Dual-Power Supply Pins for Primary and Backup Power Supplies Optional Trickle Charge Output to Backup Supply 2.0V to 5.5V Operation Optional Industrial Temperature Range: -40°C to +85°C Available in Space-Efficient, 20-Pin TSSOP Package Underwriters Laboratory (UL) Recognized PIN CONFIGURATIONS www.maxim-ic.com DS1306 Serial Alarm Real-Time Clock SPI is a trademark of Motorola, Inc. TSSOP (4.4mm) VCC2 VBAT N.C. N.C. INT0 INT1 1Hz GND VCC1 N.C. 32kHz VCCIF SDO SDI SCLK CE SERMODE N.C. VCC2 DIP (300 mils) INT0 1Hz GND VCC1 SDO SDI SCLK CE SERMODE VBAT INT1 32kHz VCCIF 19-5056; Rev 12/09
ORDERING INFORMATION
PART TEMP RANGE PIN-PACKAGE TOP MARK* DS1306 0°C to +70°C 16 DIP (300 mils) DS1306 DS1306+ 0°C to +70°C 16 DIP (300 mils) DS1306 + DS1306N -40°C to +85°C 16 DIP (300 mils) DS1306N DS1306N+ 0°C to +70°C 16 DIP (300 mils) DS1306N + DS1306E 0°C to +70°C 20 TSSOP (173 mils) DS1306 DS1306E+ 0°C to +70°C 20 TSSOP (173 mils) DS1306 + DS1306EN -40°C to +85°C 20 TSSOP (173 mils) DS1306N DS1306EN+ -40°C to +85°C 20 TSSOP (173 mils) DS1306N + DS1306EN/T&R -40°C to +85°C 20 TSSOP (173 mils) DS1306N DS1306EN+T&R -40°C to +85°C 20 TSSOP (173 mils) DS1306N + DS1306E/T&R 0°C to +70°C 20 TSSOP (173 mils) DS1306 DS1306E+T&R 0°C to +70°C 20 TSSOP (173 mils) DS1306 + +Denotes a lead(Pb)-free/RoHS-compliant package T&R = Tape and reel. *An “N” on the top mark indicates an industrial device. PIN DESCRIPTION PIN TSSOP DIP NAME FUNCTION 1 1 V CC2 Backup Power Supply. This is the secondary power supply pin. In systems using the trickle charger, the rechargeable energy source is connected to this pin. 2 2 V BAT Battery Input for Any Standard +3V Lithium Cell or Other Energy Source. If not used, VBAT must be connected to ground. Diodes must not be placed in series between VBAT and the battery, or improper operation will result. UL recognized to ensure against reverse charging current when used in conjunction with a lithium battery. See “Conditions of Acceptability” at www.maxim-ic.com/TechSupport/QA/ntrl.htm. 3 3 X1 5 4 X2 Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator is designed for operation with a crystal having a specified load capacitance of 6pF. For more information on crystal selection and crystal layout considerations, refer to Application Note 58, “Crystal Considerations with Dallas Real-Time Clocks.” The DS1306 can also be driven by an external 32.768kHz oscillator. In this configuration, the X1 pin is connected to the external oscillator signal and the X2 pin is floated. 7 5 INT0 Active-Low Interrupt 0 Output. The INT0 pin is an active-low output of the DS1306 that can be used as an interrupt input to a processor. The INT0 pin can be programmed to be asserted by Alarm 0. The INT0 pin remains low as long as the status bit causing the interrupt is present and the corresponding interrupt enable bit is set. The INT0 pin operates when the DS1306 is powered by VCC1, VCC2, or VBAT. The INT0 pin is an open-drain output and requires an external pullup resistor. 8 6 INT1 Interrupt 1 Output. The INT1 pin is an active-high output of the DS1306 that can be used as an interrupt input to a processor. The INT1 pin can be programmed to be asserted by Alarm 1. When an alarm condition is present, the INT1 pin generates a 62.5ms active-high pulse. The INT1 pin operates only when the DS1306 is powered by V CC2 or VBAT. When active, the INT1 pin is internally pulled up to VCC2 or VBAT. When inactive, the INT1 pin is internally pulled low.
PIN DESCRIPTION (continued) PIN TSSOP DIP NAME FUNCTION 9 7 1Hz 1Hz Output. The 1Hz pin provides a 1Hz square wave output. This output is active when the 1 Hz bit in the control register is a logic 1. Both INT0 and 1Hz pins are open-drain outputs. The interrupt, 1Hz signal, and the internal clock continue to run regardless of the level of VCC (as long as a power source is present). 10 8 GND Ground 11 9 SERMODE Serial Interface Mode. The SERMODE pin offers the flexibility to choose between two serial interface modes. When connected to GND, standard 3-wire communication is selected. When connected to VCC, SPI communication is selected. 12 10 CE Chip Enable. The chip enable signal must be asserted high during a read or a write for both 3-wire and SPI communication. This pin has an internal 55k pulldown resistor (typical). 14 11 SCLK Serial Clock. SCLK is used to synchronize data movement on the serial interface for either the SPI or 3-wire interface. 15 12 SDI Serial Data In. When SPI communication is selected, the SDI pin is the serial data input for the SPI bus. When 3-wire communication is selected, this pin must be tied to the SDO pin (the SDI and SDO pins function as a single I/O pin when tied together). 16 13 SDO Serial Data Out. When SPI communication is selected, the SDO pin is the serial data output for the SPI bus. When 3-wire communication is selected, this pin must be tied to the SDI pin (the SDI and SDO pins function as a single I/O pin when tied together). V CCIF provides the logic-high level. 17 14 V CCIF Interface Logic Power-Supply Input. The VCCIF pin allows the DS1306 to drive SDO and 32kHz output pins to a level that is compatible with the interface logic, thus allowing an easy interface to 3V logic in mixed supply systems. This pin is physically connected to the source connection of the p-channel transistors in the output buffers of the SDO and 32kHz pins. 18 15 32kHz 32.768kHz Output. The 32kHz pin provides a 32.768kHz output. This signal is always present. VCCIF provides the logic-high level. 20 16 V CC1 Primary Power Supply. DC power is provided to the device on this pin. VCC1 is the primary power supply. 4, 6, 13, 19 — N.C. No Connection
DESCRIPTION
The DS1306 serial alarm real-time clock (RTC) provi des a full binary coded decimal (BCD) clock calendar that is accessed by a simple serial interf ace. The clock/calendar provides seconds, minutes, hours, day, date, month, and year info rmation. The end of the month date is automatically adjusted for months with fewer than 31 days, in cluding corrections for leap year. Th e clock operates in either the 24- hour or 12-hour format with AM/PM indicator. In a ddition, 96 bytes of NV RAM are provided for data storage. An interface logic power-supply input pin (V CCIF) allows the DS1306 to drive SDO and 32kHz pins to a level that is compatible with the interface logic. This allows an easy interface to 3V logic in mixed supply systems. The DS1306 offers dual-power supplies as we ll as a battery-input pi n. The dual-power supplies support a programmable trickle charge circuit that allows a rechargeable energy source (such as a super cap or rechargeable battery) to be used for a backup supply. The V BAT pin allows the device to be backed up by a non-rechargeable battery. The DS1306 is fully operational from 2.0V to 5.5V. Two programmable time-of-day alarms are provi ded by the DS1306. Each alarm can generate an interrupt on a programmable 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. A 1Hz and a 32kHz clock output are also available. The DS1306 supports a direct interface to SPI serial data ports or standard 3-wire interface. An easy-to- use address and data format is implemented in whic h data transfers can occur 1 byte at a time or in multiple-byte burst mode. OPERATION The block diagram in Figure 1 show s the main elements of the serial alarm RTC. The following paragraphs describe the function of each pin. Figure 1. BLOCK DIAGRAM
Note 58: Crystal Considerations with Dallas Real-Time Clocks for detailed information. Table 1. Crystal Specifications Application Note 58: Crystal Considerations for Dallas Real-Time Clocks for additional specifications. register increments at midnight. Illogical time and date entries result in undefined operation. one second after writing the seconds register ensures consistent data. Terminating a write before the last bit is sent aborts the write for that byte. mode, the user copy is static while the internal registers continue to increment.
Figure 2. RTC REGISTERS AND ADDRESS MAP Note: Range for alarm registers does not include mask’m’ bits.
is set to a logic 1, an alarm occurs every second. the corresponding alarm interrupt enable bit is enabled, an interrupt output is activated. Table 2. TIME-OF-DAY ALARM MASK BITS that control the real-time clock, interrupts, and trickle charger.
0 WP 0 0 0 1Hz AIE1 AIE0
control register bit can be written. is enabled. When this bit is a logic 0, the 1Hz output is high-Z. not initiate the INT0 signal. not initiate an interrupt signal, and the INT1 pin is set to a logic 0 state.
activated when the device is powered by VCC1, VCC2, or VBAT. Figure 3. PROGRAMMABLE TRICKLE CHARGER
Table 3. TRICKLE CHARGER RESISTOR AND DIODE SELECT If RS is 00, the trickle charger is disabled independently of TCS. VBAT + 0.2V. The device is write-protected whenever it is switched to VBAT. VCC2, VCC2 powers the DS1306. The DS1306 does not write-protect itself in this configuration. battery. In this case, the VCC1 and VBAT pins are grounded and the battery is connected to the VCC2 pin. Only these three configurations are allowed. Unused supply pins must be grounded.
Figure 4. POWER-SUPPLY CONFIGURATIONS NOTE: DEVICE DOES NOT PROVIDE AUTOMATIC WRITE PROTECTION. NOTE: DEVICE IS WRITE-PROTECTED IF VCC < VCCTP.
determined by the SERMODE pin. When this pin is connected to V CC, SPI communication is selected. When this pin is connected to ground, standard 3-wire communication is selected. 68HC11A8. The SPI mode of serial communication is selected by tying the SERMODE pin to VCC. microcontroller being the master. movement between the master (microcontroller) and the slave (DS1306) devices. bit transferred. Address and data bits are transferred in groups of eight, MSB first. Figure 5. SERIAL CLOCK AS A FUNCTION OF MICROCONTROLLER NOTE 1: CPHA BIT POLARITY (IF APPLICABLE) MAY NEED TO BE SET ACCORDINGLY. NOTE 2: CPOL IS A BIT THAT IS SET IN THE MICROCONTROLLER’S CONTROL REGISTER. NOTE 3: SDO REMAINS AT HIGH-Z UNTIL 8 BITS OF DATA ARE READY TO BE SHIFTED OUT DURING A READ.
Figure 8. SPI MULTIPLE-BYTE BURST TRANSFER around after reaching 7Fh (FFh for writes). mode, where each byte is shifted in MSB first. rising edge of SCLK and output on the falling edge of SCLK.
Figure 9. 3-WIRE SINGLE BYTE TRANSFER NOTE: IN BURST MODE, CE IS KEPT HIGH AND ADDITIONAL SCLK CYCLES ARE SENT UNTIL THE END OF THE BURST. *I/O IS SDI AND SDO TIED TOGETHER.
Soldering Temperature.……………………………….Refer to the IPC/JEDEC Standard J-STD-020 Specification This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time can affect reliability. OPERATING RANGE RANGE TEMP RANGE V CC (V) Commercial 0°C to +70°C 2.0 to 5.5 V CC1 or VCC2 Industrial -40°C to +85°C 2.0 to 5.5 V CC1 or VCC2 RECOMMENDED DC OPERATING CONDITIONS (TA = Over the operating range, unless otherwise specified.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Supply Voltage VCC1, VCC2 VCC1, VCC2 2.0 5.5 V 1, 8 Logic 1 Input VIH 2.0 V CC + 0.3 V VCC = 2.0V +0.3 Logic 0 Input VIL VCC = 5V -0.3 +0.8 V VBAT Battery Voltage VBAT 2.0 5.5 V VCCIF Supply Voltage VCCIF 2.0 5.5 V 10
DC ELECTRICAL CHARACTERISTICS (TA = Over the operating range, unless otherwise specified.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Leakage ILI -100 +500 A Output Leakage ILO -1 +1 A Logic 1 Output Current (INT1 pin) IOH, INT1 (VCC2, VBAT) -0.3V -100 A VCC1 = 2.0V 0.425 VCC1 Active Supply Current I CC1A VCC1 = 5V 1.28 mA 2, 7 VCC1 = 2.0V 25.3 VCC1 Timekeeping Current I CC1T VCC1 = 5V 81 A 1, 7 VCC2 = 2.0V 0.4 VCC2 Active Supply Current I CC2A VCC2 = 5V 1.2 mA 2, 8 VCC2 = 2.0V 0.4 VCC2 Timekeeping Current I CC2T VCC2 = 5V 1 A 1, 8 Battery Timekeeping Current I BAT V BAT = 3V 550 nA 9 Battery Timekeeping Current (IND) I BAT V BAT = 3V 800 nA 9 VCC Trip Point VCCTP VBAT -
50 VBAT +
R2 4 Trickle Charge Resistors R3 8 Trickle Charger Diode Voltage Drop V TD 0.7 V CAPACITANCE (TA = +25C) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES Input Capacitance CI 10 pF Output Capacitance CO 15 pF
3-WIRE AC ELECTRICAL CHARACTERISTICS (TA = Over the operating range, unless otherwise specified.) (Figure 10 and Figure 11) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES VCC = 2.0V 200 Data to CLK Setup tDC VCC = 5V 50 ns 3, 4 VCC = 2.0V 280 CLK to Data Hold tCDH VCC = 5V 70 ns 3, 4 VCC = 2.0V 800 CLK to Data Delay tCDD VCC = 5V 200 ns 3, 4, 5 VCC = 2.0V 1000 CLK Low Time tCL VCC = 5V 250 ns 4 VCC = 2.0V 1000 CLK High Time tCH VCC = 5V 250 ns 4 VCC = 2.0V 0.6 CLK Frequency tCLK VCC = 5V DC 2.0 MHz 4 VCC = 2.0V 2000 CLK Rise and Fall tR, tF VCC = 5V 500 ns VCC = 2.0V 4 CE to CLK Setup tCC VCC = 5V 1 s 4 VCC = 2.0V 240 CLK to CE Hold tCCH VCC = 5V 60 ns 4 VCC = 2.0V 4 CE Inactive Time tCWH VCC = 5V 1 s 4 VCC = 2.0V 280 CE to Output High-Z tCDZ VCC = 5V 70 ns 3, 4 VCC = 2.0V 280 SCLK to Output High-Z tCCZ VCC = 5V 70 ns 3, 4
SPI AC ELECTRICAL CHARACTERISTICS (TA = Over the operating range, unless otherwise specified.) PARAMETER SYMBOL MIN TYP MAX UNITS NOTES VCC = 2.0V 200 Data to CLK Setup tDC VCC = 5V 50 ns 3, 4 VCC = 2.0V 280 CLK to Data Hold tCDH VCC = 5V 70 ns 3, 4 VCC = 2.0V 800 CLK to Data Delay tCDD VCC = 5V 200 ns 3, 4, 5 VCC = 2.0V 1000 CLK Low Time tCL VCC = 5V 250 ns 4 VCC = 2.0V 1000 CLK High Time tCH VCC = 5V 250 ns 4 VCC = 2.0V 0.6 CLK Frequency tCLK VCC = 5V DC 2.0 MHz 4 VCC = 2.0V 2000 CLK Rise and Fall tR, tF VCC = 5V 500 ns VCC = 2.0V 4 CE to CLK Setup tCC VCC = 5V 1 s 4 VCC = 2.0V 240 CLK to CE Hold tCCH VCC = 5V 60 ns 4 VCC = 2.0V 4 CE Inactive Time tCWH VCC = 5V 1 s 4 VCC = 2.0V 280 CE to Output High-Z tCDZ VCC = 5V 70 ns 3, 4
NOTES: 1) ICC1T and ICC2T are specified with CE set to a logic 0. 2) ICC1A and ICC2A are specified with CE = V CC, SCLK = 2MHz at V CC = 5V; SCLK = 500kHz at V CC = 2.0V, VIL = 0V, VIH = VCC. 3) Measured at VIH = 2.0V or VIL = 0.8V and 10ms maximum rise and fall time. 4) Measured with 50pF load. 5) Measured at VOH = 2.4V or VOL = 0.4V. 6) VCC = VCC1, when VCC1 > VCC2 + 0.2V (typical); VCC = VCC2, when VCC2 > VCC1. 7) VCC2 = 0V. 8) VCC1 = 0V. 9) VCC1 < VBAT. 10) VCCIF must be less than or equal to the largest of VCC1, VCC2, and VBAT.
PACKAGE INFORMATION
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAG E CODE DOCUMENT NO.
16 PDIP P16+1 21-0043
20 TSSOP U20+1 21-0066
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2009 Maxim Integrated Products Maxim Is a registered trademark of Maxim Integrated Products, Inc.
REVISION HISTORY
Added Table 1. Crystal Specifications to the Clock Accuracy section. 5 Added “SERMODE = VCC” to Figures 6, 7, 12, and 13. 12, 20 Added “SERMODE = GND” to Figures 9, 10, and 11. 14, 18 12/09 Removed the “Crystal Capacitance” parameter from the Capacitance table. 16