Component comparison · Last verified 2026-07-27
DS3231M+ and DS3231S# share a 400 kHz I2C interface, two alarms, battery backup and a compatible 16-pin footprint, but they use different timing technologies. DS3231M+ integrates a temperature-compensated MEMS resonator and specifies ±5 ppm across a wide range. DS3231S# integrates a TCXO and crystal and offers tighter ppm limits. Select by accuracy, environment and qualification requirements.
DS3231M+ vs DS3231S# specifications
| Specification | DS3231M+ | DS3231S# |
|---|---|---|
| Timebase | Integrated temperature-compensated MEMS resonator | Integrated crystal and TCXO |
| Specified timekeeping accuracy | ±5 ppm from -45°C to +85°C | ±2 ppm from 0°C to +40°C; ±3.5 ppm from -40°C to +85°C |
| Orderable temperature grade | Industrial, -40°C to +85°C | Commercial, 0°C to +70°C |
| Serial interface | I2C up to 400 kHz | I2C up to 400 kHz |
| Supply voltage | 2.3 V to 5.5 V | 2.3 V to 5.5 V |
| Time-of-day alarms | Two | Two |
| Battery backup | Supported | Supported |
| User SRAM | None | None |
| Package / case | 16-pin wide SOIC, 300 mil | 16-pin wide SOIC, 300 mil |
| Digital temperature sensor | ±3°C accuracy output | ±3°C accuracy output |
Key differences
The oscillator technology is different
DS3231M+ uses an internal temperature-compensated MEMS resonator, while DS3231S# integrates a temperature-compensated crystal oscillator and crystal. This affects the accuracy specification and the environmental behavior that must be included in the system timing budget.
The guaranteed accuracy limits are not the same
DS3231M+ specifies ±5 ppm across -45°C to +85°C. The DS3231 family specifies ±2 ppm from 0°C to +40°C and ±3.5 ppm from -40°C to +85°C; the S# orderable code is the commercial-temperature version.
Footprint compatibility still requires an engineering review
Analog Devices describes DS3231M as footprint and functionally compatible with DS3231, but a BOM change must still check the complete orderable code, electrical limits, output behavior, accuracy budget, firmware assumptions and qualification requirements.
Can these parts be interchanged?
Analog Devices describes DS3231M as footprint and functionally compatible with DS3231, but that statement does not remove the need for design verification. DS3231M+ and DS3231S# use different resonator technologies and have different accuracy and temperature specifications. Confirm the exact package drawing, pin functions, supply and backup limits, I2C behavior, clock outputs, alarm behavior, timing budget, software assumptions and environmental qualification before approving a substitution.
- Electrical ratings and operating conditions
- Package dimensions, footprint and pinout
- Interface, timing and firmware behavior
- Temperature and qualification grade
- Lifecycle status and current documentation revision
DS3231M+ vs DS3231S# FAQ
What is the main difference between DS3231M+ and DS3231S#?
DS3231M+ uses an integrated temperature-compensated MEMS resonator, while DS3231S# uses an integrated TCXO and crystal. Their interface and major RTC functions are similar, but their accuracy limits differ.
Which device has the tighter timekeeping accuracy specification?
DS3231S# belongs to the crystal-based DS3231 family, which specifies ±2 ppm from 0°C to +40°C. DS3231M+ specifies ±5 ppm across -45°C to +85°C.
Is DS3231M+ footprint compatible with DS3231S#?
Analog Devices describes DS3231M as footprint and functionally compatible with DS3231. The exact orderable codes, package drawing, electrical limits, outputs and system timing budget still need to be verified.
Do DS3231M+ and DS3231S# use the same I2C interface?
Both support an I2C interface up to 400 kHz and provide two time-of-day alarms. Firmware should still be checked for assumptions about status bits, clock outputs, calibration and temperature behavior.
When is DS3231M+ the closer choice?
DS3231M+ is the closer candidate when a MEMS-based timing reference, wide specified accuracy range and industrial environment are important. DS3231S# is the closer candidate when the tighter crystal-based ppm limit is required.
Sources and verification
- Analog Devices DS3231M product page
- Analog Devices DS3231M datasheet
- Analog Devices DS3231 product page
- Analog Devices DS3231 datasheet
This comparison supports preliminary selection and sourcing review. Similar specifications do not establish drop-in compatibility. Confirm the complete orderable code and current manufacturer documentation before design release or purchase.
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