DS3231MZ+ - ±5ppm I2C RTC with TCXO | Maxim Integrated
MPN: DS3231MZ+ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.75 | $275.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.2 | $2,200.00 |
| 3,000 | $1.95 | $5,850.00 |
DS3231MZ+ Overview
A real-time clock (RTC) is a dedicated low-power timing IC that keeps wall-clock time (seconds, minutes, hours, day, date, month, year) independently of the main MCU. It sits in the system hierarchy alongside power management and supervision ICs, between the backup battery and the host processor. Unlike an MCU's internal timer, an RTC continues counting during main power loss, making it the canonical block for data-logger timestamping, scheduled wake-ups, and any application that must remember "when" across power cycles. The DS3231M family specifically replaces a discrete crystal + TCXO with an on-chip MEMS resonator, eliminating PCB crystal layout and trimming steps.
Key features include ±5 ppm accuracy (±2.17 minutes/year) without user calibration, integrated MEMS resonator that removes external crystal requirements, automatic backup switching to a battery on VCC loss, two programmable time-of-day alarms, a square-wave output (1 Hz, 1.024 kHz, 4.096 kHz, 8.192 kHz), and an I2C bus rated to 400 kHz fast mode. The 8-SOIC package is pin-compatible with the popular DS1307 footprint family and other 8-pin RTCs. Operating temperature spans the industrial -40°C to +85°C range, and the part consumes roughly 110 µA active and 3 µA in timekeeping mode with VCC removed.
The DS3231M uses a silicon MEMS resonator trimmed at the factory, eliminating the need for external load capacitors or PCB crystal layout. An on-chip temperature sensor drives a compensation circuit that adjusts the counter, achieving the ±5 ppm rating without user intervention. Battery-backup mode is transparent to the user: when VCC drops below the battery voltage, an internal switch redirects the supply to the backup source and the oscillator keeps running. Per the manufacturer datasheet, the BB32 pin accepts a 3 V lithium cell (CR2032 typical) and the device draws 3 µA from the battery in timekeeping mode.
Typical applications include Arduino/Raspberry Pi data-logger timestamps, IoT sensor nodes that wake on RTC alarm, point-of-sale terminals requiring accurate transaction time, GPS-disciplined wall-clock backup, and industrial controllers with scheduled logging. The 8-SOIC footprint drops onto thousands of existing DS3231 / DS1307 module PCBs, making it the lowest-effort upgrade from generic crystal RTCs.
When designing with the DS3231MZ+, place a 0.1 µF decoupling capacitor as close as possible to VCC and a backup battery on the BB32 pin through a decoupling network; ensure the I2C lines (SCL, SDA) are pulled up to VCC with 4.7 kΩ resistors for reliable 400 kHz operation. The INT/SQW pin can be left open or used as an interrupt source for the host MCU.
This page synthesizes distributor pricing, drop-in alternatives in the same 8-SOIC package, and practical design notes that go beyond what is found in the manufacturer datasheet alone.
Drop-in alternatives for DS3231MZ+ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
DS3231M+
✅ Drop-In📋 Reference alternative (not in catalog)
DS3231M+TRL
✅ Drop-In📋 Reference alternative (not in catalog)
DS3232MZ+
✅ Drop-In📋 Reference alternative (not in catalog)
DS3231SN#
✅ Drop-In📋 Reference alternative (not in catalog)
MCP79410-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
DS3231MZ+ Specifications
| Function | Real-Time Clock (RTC) with TCXO/MEMS resonator |
| Interface | I2C, 2-Wire Serial (up to 400 kHz) |
| Date Format | YY-MM-DD-dd |
| Time Format | HH:MM:SS (12/24 hour) |
| Supply Voltage | 2.3 V to 5.5 V |
| Accuracy | ±5 ppm (0°C to +50°C) |
| Operating Temperature | -40°C to +85°C |
| Battery Backup Current | 3 µA (timekeeping mode) |
| Memory Size | None (RTC only, no NV SRAM) |
| Package / Case | 8-SOIC (0.154", 3.90 mm width) |
| Mounting Type | Surface Mount |
| Number of Pins | 8 |
| Alarms | 2 programmable time-of-day alarms |
| Square-Wave Output | 1 Hz, 1.024 kHz, 4.096 kHz, 8.192 kHz |
| Resonator Type | Integrated MEMS (no external crystal required) |
| RoHS Status | Compliant |
DS3231MZ+ Pin Configuration
| Pin 1 | INT/SQW — Interrupt or square-wave output |
| Pin 2 | SDA — I2C data (open-drain, requires pull-up) |
| Pin 3 | SCL — I2C clock (open-drain, requires pull-up) |
| Pin 4 | VBAT — Backup battery input (3 V lithium cell) |
| Pin 5 | GND — Ground |
| Pin 6 | VCC — Main supply, 2.3 V to 5.5 V |
| Pin 7 | NC — Not connected (per datasheet) |
| Pin 8 | NC — Not connected (per datasheet) |
Typical Applications
DS3231MZ+ is suitable for 6 applications: Arduino / Raspberry Pi Data Logger Timestamping, IoT Sensor Node with RTC Alarm Wake, Point-of-Sale Terminal Timekeeping, GPS-Disciplined Wall-Clock Backup, Industrial Controller Scheduled Logging, Consumer Electronics Display Clock.
Arduino / Raspberry Pi Data Logger Timestamping
The DS3231MZ+ is the default RTC companion for Arduino UNO, ESP32, and Raspberry Pi data-logger projects that must timestamp readings when the host MCU is offline or when network time (NTP) is unavailable. The integrated MEMS resonator eliminates the external 32.768 kHz crystal and load capacitors, so a complete battery-backed real-time clock fits on two I2C lines and one coin cell. At ±5 ppm (≈ ±2.17 minutes/year), timestamps remain trustworthy across multi-month sensor deployments, and the 3 µA backup current lets a CR2032 hold time for over a decade. Drop the chip on any ZS-042 module footprint, load a DS3231 library, and log timestamps with millisecond-level consistency between power cycles.
Recommended
IoT Sensor Node with RTC Alarm Wake
Battery-powered IoT sensor nodes rely on the DS3231MZ+ to wake the host periodically using its two programmable time-of-day alarms. While the host sleeps in deep-sleep mode drawing microamps, the RTC continues ticking on the backup cell; when the alarm fires, the INT/SQW pin asserts and the host wakes, reads sensors, and transmits. This pattern extends coin-cell life from weeks to years compared with MCU-internal timers that drift and force frequent re-syncs. The 2.3 V to 5.5 V supply range supports both 3.3 V ESP32 nodes and 5 V Arduino variants without level shifting, and the 8-SOIC footprint integrates easily above the host PCB.
Recommended
Point-of-Sale Terminal Timekeeping
POS terminals, payment terminals, and fiscal printers require accurate transaction timestamps that survive power interruptions and accidental power-cord pulls. The DS3231MZ+ provides ±5 ppm accuracy, integrated MEMS resonator, and transparent battery-backup switching, so transaction logs always carry the correct wall-clock time even when the main supply is removed at end-of-day. The 8-SOIC package and I2C interface integrate into the terminal mainboard with a CR2032 backup cell providing months of holdover. Its two alarms can drive end-of-day and audit-log events without burdening the application processor.
Recommended
GPS-Disciplined Wall-Clock Backup
Wall clocks, industrial time displays, and GPS-disciplined clocks use the DS3231MZ+ as a holdover oscillator when GPS signals are lost (indoor mounting, antenna failure, jamming). With ±5 ppm accuracy, the RTC keeps time within seconds per day even without GPS correction for weeks at a time. The 1 Hz square-wave output can directly drive a stepper motor or counter, while the INT/SQW alarm output triggers periodic display refreshes. The 8-SOIC and battery backup make the DS3231MZ+ a maintenance-free upgrade from legacy DS1307 crystal RTCs in clock modules.
Recommended
Industrial Controller Scheduled Logging
PLCs, industrial controllers, and SCADA peripherals use the DS3231MZ+ to time-stamp event logs, scheduled maintenance tasks, and time-of-use metering where regulatory accuracy is required. The wide -40°C to +85°C industrial operating range handles factory-floor conditions, and the integrated MEMS resonator eliminates crystal aging concerns in high-vibration environments. Battery backup keeps the clock running through power outages so the controller never has to re-acquire time on restart. The 8-SOIC package and 400 kHz I2C interface drop into any embedded controller with two free GPIO pins.
Recommended
Consumer Electronics Display Clock
Microwave ovens, washing machines, audio receivers, and home automation panels use the DS3231MZ+ to maintain wall-clock time across power cycles, including brief outages and standby mode. The integrated MEMS resonator means no crystal or trimming is needed during assembly, lowering manufacturing cost and improving yield. The INT/SQW pin can drive the display multiplex directly or trigger the host to refresh the time on wake. Combined with a coin cell, the clock stays accurate for the lifetime of the product without user intervention.
Recommended
Recommended Products Summary
Engineering reference data for DS3231MZ+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | DS3231M+ | DS3232MZ+ | DS3231SN# | MCP79410-I/SN |
|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Microchip Technology |
| Package | 8-SOIC (0.154", 3.90 mm) | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same |
| Supply Voltage | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 1.8 V to 5.5 V |
| Accuracy | ±5 ppm (0°C to +50°C) | ±5 ppm | ±5 ppm | ±2 ppm (external crystal) | ±5 ppm typical |
| External Crystal Required | No (integrated MEMS) | No | No | Yes (32.768 kHz) | No (integrated resonator) |
| SRAM | None | None | 236 bytes | None | 64 bytes |
| Interface Speed | I2C up to 400 kHz | 400 kHz | 400 kHz | 400 kHz | 400 kHz |
| Operating Temperature | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C |
Key Differentiators
- Integrated MEMS resonator eliminates external crystal BOM (vs DS3231SN#)
- Pin-compatible upgrade path for DS1307 module footprints (vs DS3231SN#)
- Cross-brand drop-in option with broader voltage range (vs MCP79410-I/SN)
Design Notes
Estimated: with VCC = 3.3 V, a CR2032 backup cell (3 V, 240 mAh), and 3 µA backup draw, holdover time is approximately 240 mAh / 3 µA = 80,000 hours ≈ 9 years, neglecting self-discharge. Place a 0.1 µF decoupling capacitor on VBAT close to the IC, and a 1 µF + 0.1 µF pair on VCC. If the application experiences rapid VCC transients, add a 100 Ω series resistor on VCC to limit inrush into the internal supply switch.
Although the DS3231MZ+ integrates the resonator, it is still sensitive to nearby thermal gradients. Route the I2C lines (SCL, SDA) with 4.7 kΩ pull-ups to VCC and keep them short. Do not place the RTC directly above or below high-current switching converter inductors; ±5 ppm accuracy assumes the temperature-compensation circuit can read the chip's own temperature correctly, which is corrupted by adjacent heat sources. A ground pour under and around the SOIC improves thermal uniformity.
Common pitfalls: (1) leaving VBAT floating - the part still works but loses backup capability; always tie VBAT to a coin cell or supply through a series diode. (2) Forgetting I2C pull-ups - the SDA/SCL lines are open-drain and the bus will not function without external 4.7 kΩ pull-ups. (3) Driving the INT/SQW pin as an input - it is an open-drain output that needs a pull-up; shorting it to VCC can damage the die. (4) Using software-only library defaults that mask the alarm enable bits; verify the CONTROL and STATUS registers in the application code.
Compliance Information
RoHS and lead-free per Maxim Integrated product page; AEC-Q100 not applicable for this consumer/industrial-grade RTC. Halogen-free status not stated in provided data.
