Keeps ticking when the power's out.
A real-time clock is a tiny IC that holds calendar time independently of your main system — running from a coin cell or backup battery for years. Critical for logging, scheduling, security and anything that must remember "when" across power cycles.
Four reasons to integrate a dedicated RTC instead of using the MCU's internal counter.
Industry's lowest backup current — a CR2032 coin cell powers the clock for over 10 years between battery changes.
Better than 1 second per month accuracy at +25 °C. Suitable for security event logging, scheduling, and audit trails.
Selected RTCs are AEC-Q100 qualified — Grade 1 (−40 to +125 °C) for engine bay and ADAS designs.
Most TDE RTCs include the 32.768 kHz crystal in the package — no external resonator, no load capacitance tuning, no PCB layout headaches.
I²C for simplicity. SPI for speed.
Choose the interface that matches your bus topology. I²C wins when you already have an I²C bus and want minimal pin count. SPI wins when latency matters or when you need to share the bus with high-throughput peripherals.
I²C Bus
The classic two-wire bus — SDA and SCL — used by virtually every embedded peripheral. Add an RTC to an existing I²C bus without using additional MCU pins.
- Only 2 wires (SDA + SCL)
- Multi-device on same bus
- Up to 400 kHz Fast Mode
- Open-drain, needs pull-ups
- Most TDE RTCs use I²C
SPI Bus
Faster, full-duplex, with dedicated chip-select per device. The right choice when the I²C bus is busy or when latency-sensitive reads (sub-microsecond) are required.
- 4 wires (SCK + MOSI + MISO + CS)
- Full-duplex, faster
- Up to 8 MHz clock
- Dedicated CS per device
- Lower-latency reads
Seiko Epson — the broadest RTC portfolio on the market.
RTCs are an EPSON specialty. The portfolio covers everything from ultra-low-power IoT chips (RX8804 family) to fully automotive-qualified parts (RX8901CE, single-source approved for ETSI / DSMR-6 smart meter gateways).
Most EPSON RTCs include the 32.768 kHz crystal in the package, so you don't need an external resonator. That cuts BOM lines, eliminates load-cap tuning, and removes a common layout failure mode.
Where RTCs count. Anywhere time outlives power.
Need an RTC? Let us narrow it down.
The RTC Finder Tool helps you pick the right part by interface, backup current, accuracy and temperature grade — or send us your requirements directly. Quote and samples within one business day.
Keeps ticking when the power's out.
A real-time clock is a tiny IC that holds calendar time independently of your main system — running from a coin cell or backup battery for years. Critical for logging, scheduling, security and anything that must remember "when" across power cycles.
Four reasons to integrate a dedicated RTC instead of using the MCU's internal counter.
Industry's lowest backup current — a CR2032 coin cell powers the clock for over 10 years between battery changes.
Better than 1 second per month accuracy at +25 °C. Suitable for security event logging, scheduling, and audit trails.
Selected RTCs are AEC-Q100 qualified — Grade 1 (−40 to +125 °C) for engine bay and ADAS designs.
Most TDE RTCs include the 32.768 kHz crystal in the package — no external resonator, no load capacitance tuning, no PCB layout headaches.
I²C for simplicity. SPI for speed.
Choose the interface that matches your bus topology. I²C wins when you already have an I²C bus and want minimal pin count. SPI wins when latency matters or when you need to share the bus with high-throughput peripherals.
I²C Bus
The classic two-wire bus — SDA and SCL — used by virtually every embedded peripheral. Add an RTC to an existing I²C bus without using additional MCU pins.
- Only 2 wires (SDA + SCL)
- Multi-device on same bus
- Up to 400 kHz Fast Mode
- Open-drain, needs pull-ups
- Most TDE RTCs use I²C
SPI Bus
Faster, full-duplex, with dedicated chip-select per device. The right choice when the I²C bus is busy or when latency-sensitive reads (sub-microsecond) are required.
- 4 wires (SCK + MOSI + MISO + CS)
- Full-duplex, faster
- Up to 8 MHz clock
- Dedicated CS per device
- Lower-latency reads
Seiko Epson — the broadest RTC portfolio on the market.
RTCs are an EPSON specialty. The portfolio covers everything from ultra-low-power IoT chips (RX8804 family) to fully automotive-qualified parts (RX8901CE, single-source approved for ETSI / DSMR-6 smart meter gateways).
Most EPSON RTCs include the 32.768 kHz crystal in the package, so you don't need an external resonator. That cuts BOM lines, eliminates load-cap tuning, and removes a common layout failure mode.
Where RTCs count. Anywhere time outlives power.
Need an RTC? Let us narrow it down.
The RTC Finder Tool helps you pick the right part by interface, backup current, accuracy and temperature grade — or send us your requirements directly. Quote and samples within one business day.