What Is the DS1307ZN RTC?

What Is the DS1307ZN?
1. The DS1307ZN is a serial real-time clock (RTC) with several notable features.
2. The DS1307ZN provides comprehensive timekeeping and calendaring functions. It keeps track of seconds, minutes, hours, day of the week, date, month, and year.
3. Time and date information is stored and communicated in Binary-Coded Decimal (BCD) format. BCD representation simplifies interfacing with digital systems, as it uses binary codes to represent decimal numbers directly.
4. The DS1307ZN automatically adjusts the end-of-month dates, accommodating months with fewer than 31 days. It also includes corrections for leap years.
5. The clock can operate in either a 24-hour or a 12-hour format, with an AM/PM indicator for the 12-hour mode.
6. The DS1307ZN is equipped with a built-in power-sense circuit that detects power failures and switches to a backup power supply if needed.
Pinout of DS1307ZN
X1: External 32.768 kHz crystal input
X2: External 32.768 kHz crystal output
VBAT: Backup battery input
GND: Ground
VCC: Power supply
SQW/OUT: Square wave output or interrupt
SCL: Serial clock line (I2C)
SDA: Serial data line (I2C)
Circuit of DS1307ZN
The DS1307ZN operates with the VCC pin supplying power, using GND as the reference. If VCC is lost, the VBAT pin takes over, ensuring the RTC continues running on the backup battery. A crystal connected between X1 and X2 generates a stable 32.768 kHz clock signal. The SCL and SDA pins facilitate I2C communication with a microcontroller, enabling the exchange of time and calendar data. The SQW/OUT pin can output a square wave signal or act as an interrupt.
Specification of DS1307ZN
Voltage - Supply: 4.5V - 5.5V
Voltage - Supply, Battery: 2.0V - 3.5V
Current Consumption (VCC): 1.5mA @ 5V
Current Consumption (VBAT): 500nA
Timekeeping Oscillator: 32.768 kHz external crystal
Communication Interface: I2C (2-wire)
Clock Format: 12-hour (with AM/PM) or 24-hour format
Calendar Range: Up to the year 2100 with automatic leap year adjustment
Date Format: YY-MM-DD-dd
Time Format: HH:MM:SS (12/24 hr)
NV SRAM: 56 bytes
Memory Size：56B
Operating Temperature: -40°C - 85°C
SQW/OUT Frequency Options: 1 Hz, 4.096 kHz, 8.192 kHz, 32.768 kHz
Package Type: 8-SOIC
Benefits and Features of DS1307ZN
- 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 2100
- 56-Byte, Battery-Backed, General-Purpose
- RAM with Unlimited Writes
- Programmable Square-Wave Output Signal
- Simple Serial Port Interfaces for Most Microcontrollers
- Low Power Operation Extends Battery Backup Run Time
- Consumes Less than 500nA in BatteryBackup Mode with Oscillator Running
- Automatic Power-Fail Detect and Switch Circuitry
- 8-Pin DIP and 8-Pin SO Minimizes Required Space
- Optional Industrial Temperature Range: -40°C to +85°C Supports Operation in a Wide Range of Applications
- Underwriters Laboratories® (UL) Recognized
The Package of DS1307ZN
The DS1307ZN is packaged in an 8-pin Small Outline Integrated Circuit (SOIC) format, which is a compact, surface-mount package ideal for space-constrained applications. The 8-SOIC package has a standardized pin layout with a 1.27mm pin pitch, allowing for easy integration onto printed circuit boards (PCBs). This package is widely used in electronic devices due to its small footprint, reliability, and ease of automated assembly.
Where to Use DS1307ZN?
The DS1307ZN is commonly used in applications requiring accurate timekeeping and calendar functions. It is available for digital clocks, time-stamping systems, and calendar-based scheduling systems. The RTC's ability to maintain time during power outages, thanks to its backup battery capability, makes it suitable for embedded systems in consumer electronics, industrial automation, and portable devices. Additionally, the DS1307ZN is used in data logging applications.
How to Select and Use DS1307ZN?
First, evaluate your application's timekeeping and calendar requirements. Additionally, prepare a stable 32.768 kHz crystal oscillator that can be connected between the X1 and X2 pins for accurate timekeeping. If your application requires timekeeping during power outages, connect a backup battery to the VBAT pin, typically between 2.0V and 3.5V.
After selecting the DS1307ZN, connect the VCC and GND pins to the power supply. Next, attach the crystal oscillator to the X1 and X2 pins, ensuring it is mounted close to the IC. Then, connect the SCL and SDA pins to the corresponding I2C lines of the microcontroller for communication. You can configure the SQW/OUT pin as a square wave output or an interrupt signal, depending on your application needs. Finally, program the microcontroller using the I2C protocol to interface with the DS1307ZN, allowing you to set and read the time and calendar data as required.
FAQs
What is the DS1307ZN used for?
The DS1307ZN is a real-time clock (RTC) used to keep track of time and date. It's commonly used in applications requiring accurate timekeeping, such as digital clocks, data loggers, and time-stamping systems.
What type of crystal oscillator is needed for the DS1307ZN?
The DS1307ZN requires a 32.768 kHz crystal oscillator, connected between the X1 and X2 pins.
Can I use the DS1307ZN in a 12-hour format?
Yes, the DS1307ZN supports both 12-hour and 24-hour clock formats. It can be configured to display time in either format, with the 12-hour format including an AM/PM indicator.
What should I do if the DS1307ZN isn’t keeping time accurately?
Check the power supply and backup battery connections. Verify that the I2C communication is correctly set up and that the microcontroller is properly programmed to handle the RTC data.