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SOP-16 · DS3231
ActiveReal-Time Clocks (RTC)
DS3231
Analog Devices · SOP-16 · Real-Time Clocks (RTC)
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Get a competitive quote within 24 hours. Volume discounts available. Shenzhen stock ships in 1-2 business days.
Overview
The DS3231 is Analog Devices' (formerly Maxim Integrated) highly accurate I²C real-time clock with an integrated temperature-compensated crystal oscillator (TCXO). Where a standard RTC using a bare 32.768 kHz crystal drifts ±20-100 ppm over temperature, the DS3231 maintains ±2 ppm (±3.5 min/year) from 0 °C to +40 °C and ±3.5 ppm over the full -40 °C to +85 °C industrial range. That is roughly 30× better than a discrete crystal solution, without any external trimming or firmware compensation.
The chip tracks seconds, minutes, hours (12- or 24-hour format), day of week, date, month and year with automatic leap-year compensation up to 2100. Two independent time-of-day alarms can wake the host MCU from deep sleep, saving significant battery energy. A square-wave output provides a calibrated 1 Hz, 1.024 kHz, 4.096 kHz or 8.192 kHz signal for external timing needs.
Supply range is 2.3 V to 5.5 V, with a battery-backup pin (VBAT) that accepts a coin cell (CR2032 or ML-1220) and keeps time when main power fails. Battery life in backup mode is typically 8-10 years from a fresh CR2032. I²C clock is up to 400 kHz (Fast Mode).
The DS3231 comes in a wide 16-pin SOP package; the DS3231MZ is the compact 8-pin MSOP variant with reduced features (no square-wave output). For even smaller footprints, the DS3234 (SPI interface) or PCF8523 (I²C, less accurate) are alternatives.
Common uses: data loggers, meters and utility timers, GPS-synced clocks (as backup between fixes), industrial controllers, medical devices, telecom timing, and any application where long-term accuracy matters without GPS or NTP.
Our Shenzhen stock includes Analog Devices DS3231SN# (SOP-16) with batch traceability to ADI authorized distribution. MOQ 1,000 pcs on tape or 100 pcs loose.
Key Features
- ±2 ppm accuracy from 0-40 °C (±3.5 min/year)
- Integrated TCXO — no external crystal needed
- Two programmable alarms plus calibrated square-wave output
- Battery backup pin (VBAT) with 8-10 year coin-cell life
Typical Applications
- Data loggers and event recorders
- Utility meters (water, gas, electricity) with time-of-use billing
- GPS-aided clocks as holdover between satellite fixes
- Industrial controllers needing accurate event timestamps
- Medical devices and alarm systems
Specifications
- Interface
- I2C (400kHz)
- Accuracy
- ±2 ppm
- Supply Voltage
- 2.3 to 5.5 V
- Battery Backup
- Yes
- Alarms
- 2
- Operating Temperature
- -40 to 85 °C
- Mounting Type
- Surface Mount
- Pins
- 16
- RoHS
- Compliant
Procurement Tips
For cost-sensitive high-volume products, evaluate the PCF85263 (NXP) or RV-3028 (Micro Crystal) — both offer similar accuracy at 30-50% lower cost in comparable packages.
Frequently Asked Questions
DS3231 vs DS1307 — what's the difference?
DS1307 uses an external 32.768 kHz crystal and drifts ±20-100 ppm over temperature (±1-5 min/month). DS3231 has an integrated TCXO and drifts ±2 ppm (±3.5 min/year). Both are I²C with the same register map layout, so firmware migration is straightforward. Always choose DS3231 for new designs — cost difference is only ~$1.
Does the DS3231 need an external crystal?
No. The TCXO is integrated. Just connect VCC, GND, SDA, SCL, VBAT (to coin cell), and optionally SQW/INT pins. This dramatically simplifies PCB layout and reduces assembly cost.
How long does the backup battery last?
A fresh CR2032 (220 mAh) with the DS3231 drawing ~1 µA in backup mode gives 8-10 years. Use a Panasonic, Maxell or Renata brand cell for reliable longevity — cheap Chinese cells may leak or lose capacity in 2-3 years.
Can I use the alarms to wake an MCU from deep sleep?
Yes. Configure the alarm for a specific time, then set INT/SQW pin to alarm-interrupt mode. The alarm pulls INT low when triggered, waking the MCU. This is a standard technique in low-power data loggers.
What I²C address does the DS3231 use?
Fixed 0x68 (7-bit). No address pins. If you need multiple DS3231 on the same bus, use an I²C multiplexer like TCA9548A.
How do I detect a counterfeit DS3231?
Genuine ADI parts have laser-etched logo plus exact part number and lot code, matte tin leads, and correct weight. Fakes are often remarked DS1307 dies that lack the TCXO — they drift ±50 ppm or worse. Test by measuring accuracy over 24 hours against GPS or NTP reference: real DS3231 stays within ±0.2 s, fakes drift 1-3 s.
MOQ and lead time?
MOQ 1,000 pcs on tape for DS3231SN#, or 100 pcs loose. ADI authorized 12-20 weeks; Shenzhen stock 1-2 days.
Alternatives & Equivalents
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