DS3234S#

Real Time Clock Overview

The DS3234S# is a low-cost, extremely accurate SPI bus real-time clock (RTC) featuring an integrated temperature-compensated crystal oscillator (TCXO) and 256 bytes of battery-backed SRAM. It manages all timekeeping functions with ±2ppm accuracy from 0°C to +40°C and ±3.5ppm from -40°C to +85°C. The device includes two programmable alarms, a square-wave output, and a digital temperature sensor with ±3°C accuracy. Operating on a 2V to 5.5V supply, it supports commercial (0°C to +70°C) and industrial (-40°C to +85°C) ranges in a 20-pin SO package.

Real Time Clock Feature Summary

• Integrated TCXO provides high accuracy: ±2ppm (0°C to +40°C) and ±3.5ppm (-40°C to +85°C).
• Includes 256 bytes of battery-backed SRAM for data retention during power loss.
• Features two programmable time-of-day alarms and a programmable square-wave output.
• Integrates a digital temperature sensor with ±3°C accuracy and an aging trim register.

Real Time Clock Applications

• Servers
• Utility Power Meters
• Telematics
• GPS Systems

Real Time Clock Procurement Notes

Verify the specific suffix against the manufacturer's ordering information to confirm the operating temperature range. The 'S' designation indicates the commercial range (0°C to +70°C), while 'SN' denotes the industrial range (-40°C to +85°C). Ensure the RoHS compliance status matches project requirements, as indicated by the '#' symbol in the part number.

Real Time Clock Selection Notes

Select the DS3234S# for applications requiring high precision within the commercial temperature range. For environments exceeding 70°C or dropping below 0°C, choose the DS3234SN# variant instead. Confirm that the system voltage remains between 2.0V and 5.5V and that the microcontroller supports the required SPI modes (1 and 3) at up to 4MHz.

Real Time Clock Part Context

The DS3234 series belongs to Maxim Integrated's (now Analog Devices) line of high-precision RTCs. It distinguishes itself by integrating the crystal resonator and TCXO circuitry, reducing component count and improving long-term stability compared to standard RTCs using external crystals. It serves as a robust timing solution for systems needing reliable timekeeping without complex external calibration.

Real Time Clock Replacement Considerations

For industrial temperature requirements, use DS3234SN#. For I2C interface alternatives, consider the DS3231 series, though pinouts and interfaces differ. Direct pin-to-pin replacements for the SPI interface are limited; verify compatibility with existing firmware and hardware layouts when switching models.

Real Time Clock FAQ

What is the function of the RST pin?

The RST pin acts as an active-low reset output indicating VCC status relative to the power-fail voltage (VPF). It also supports a pushbutton input function for generating a microprocessor reset.

How does the device handle power failure?

When VCC drops below VPF, the device switches to the VBAT backup supply. If VCC falls below both VPF and VBAT, read/write access is inhibited to preserve battery life, but timekeeping continues.

What is the maximum SPI clock frequency?

The SPI bus supports frequencies up to 4MHz when VCC is between 2.7V and 5.5V, and up to 2MHz when VCC is between 2.0V and 2.7V.