DS1302S+

DS1302S+ is a Dallas/Maxim real-time clock (RTC) with battery-backed timekeeping and on-chip RAM. It maintains seconds, minutes, hours, day, date, month, and year, plus 31 bytes of non-volatile RAM for data logging. Time data are read/written through a simple 3-wire serial interface (CE, I/O, SCLK), avoiding I2C/SPI. An external 32.768 kHz crystal provides the clock, and a trickle-charge circuit keeps a backup battery charged when main power is present. It operates from 2.0 to 5.5 V and draws only microamps in battery-backed mode, suitable for low-power apps. Features include 24/12-hour formats, leap-year handling, and automatic calendar rollover. It’s easy to integrate with microcontrollers via a burst/read register protocol. Compared with newer RTCs (e.g., DS3231), DS1302S+ is typically cheaper and simpler but offers lower accuracy and temperature stability.

Here are the main features of DS1302S+ (RTC chip):
- Real-time clock and calendar with automatic leap-year handling
- 24/12-hour modes; time/date stored in BCD
- External 32.768 kHz crystal for accurate timekeeping
- VBAT backup with on-chip trickle-charge circuit for backup power
- 3-wire serial interface (CE, CLK, IO) with a bidirectional data I/O
- 31 bytes of non-volatile RAM accessible via the interface
- Programmable square-wave/IF output (SQW) for periodic interrupts
- Wide operating voltage: ≈2.0 V to 5.5 V
- Low power consumption in battery/standby operation
- Available in common packages (e.g., DIP8, SOIC)
Note: the DS1302S+ is a variant of the DS1302 family; exact register map and timing can vary by vendor, so consult the datasheet for precise register details.

- Pin count: 8 pins (DIP-8/SO-8).
- Function: Real-time clock/calendar (RTC) with a 32.768 kHz oscillator, battery backup, and a 3‑wire serial interface (CE, CLK, IO) to read/write time/date and RAM registers; includes optional trickle-charge path for a backup battery (via two pins).

- Manufacturer: Dallas Semiconductor (DS1302S+). Dallas Semiconductor is now part of Maxim Integrated, which in turn is part of Analog Devices.
- What kind of company: A semiconductor company that designs and manufactures integrated circuits (ICs), including real-time clocks, memory, and other analog/digital ICs.

DS1302S+ is a battery-backed real-time clock with 32.768 kHz oscillator, time/date calendar, 31 bytes RAM and alarm features. Common application areas:
- Embedded systems needing accurate time: clocks, timers, calendars, time-based gating
- Data logging and metering: timestamped sensor readings in environmental monitors, energy meters, loggers
- Event stamping and scheduling: alarms, security logs, scheduled actions
- Industrial automation and PLCs: timed control sequences, interval measurements
- Communications and networking: packet timestamps, maintenance windows, time references
- Portable devices with battery backup: handheld instruments, remote sensors, wearables needing persistent time during power loss

DS1302S+ is an 8-pin RTC, available in DIP-8 and SOP-8 (SOIC-8) packages.