DS1307+
DS1307+ - I2C RTC with 56B SRAM | Maxim Integrated
The Maxim Integrated DS1307+ is a low-power, 64 x 8 serial real-time clock with 56 bytes of nonvolatile SRAM, I2C communication, and an 8-pin PDIP package. It tracks seconds, minutes, hours, day, date, month, and year in binary-coded decimal format, while automatically accounting for months with fewer than 31 days. The device operates from a single 5V supply and communicates through a two-wire, bidirectional serial bus. Its low-power design makes it suitable for embedded systems that retain calendar time when the main supply is removed.
A real-time clock is a dedicated timekeeping integrated circuit that continues tracking wall-clock time independently of a microcontroller’s main program. The DS1307+ belongs to the RTC and clock/calendar category, within broader timing and embedded semiconductor systems. Its internal registers provide seconds, minutes, hours, calendar fields, and control/status information, while the SRAM provides 56 bytes for general nonvolatile data such as configuration values, counters, or small status records.
The principal features include a 64 x 8 register space, BCD clock and calendar data, automatic end-of-month adjustment, I2C serial access, and a two-wire interface. Address and data are transferred serially over the same bus, allowing a host microcontroller to initialize the oscillator, read the current time, write new time values, and access the SRAM. The verified manufacturer page identifies the DS1307 as a production part and lists a starting list price of $2.39, while LCSC reports DS1307+ pricing from $2.9452.
The DS1307+ uses an external 32.768 kHz crystal as its timebase. Crystal selection and layout strongly influence accuracy, so the oscillator should be placed close to the device and surrounded by a quiet ground return. The I2C bus requires pull-up resistors, and the device’s 5V-only supply requirement should be checked against the host system before substitution. The 8-DIP package is suitable for through-hole prototype boards, but a surface-mount variant would be preferable in compact production designs when pin compatibility is not required.
Typical uses include microcontroller data loggers, industrial controllers, embedded instrumentation, access-control systems, and products requiring calendar timestamps after power loss. The I2C interface also makes the DS1307+ convenient for systems already using PCF8574, PCA9557, STM32, MSP430, or similar embedded controllers. Its SRAM can retain small operating parameters without using the MCU’s nonvolatile memory.
When designing around the DS1307+, verify the complete pinout, crystal connection, supply decoupling, I2C pull-up arrangement, and battery-backed supply architecture before layout release. Firmware must also use the correct device address and BCD register format. For designs where higher time accuracy or a smaller surface-mount footprint is required, a temperature-compensated RTC may be a better architectural choice.
This page combines verified manufacturer information, distributor availability, package details, application guidance, and honest replacement analysis. It also distinguishes true drop-in interchangeability from functional alternatives that may require firmware, PCB, or crystal changes.
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