Renesas real-time clocks (RTC IC) are ultra-low-power clock/date devices with programmable time-of-day alarms and programmable square-wave outputs. These devices offer high noise immunity, low current consumption, 12/24 hour mode of operation, auto-correction for leap year, and programmable square wave output, making them ideal for a wide range of design applications.
Renesas' real-time clock ICs count seconds, minutes, hours, day, date, month, and year with leap-year compensation valid up to 2100. The devices feature normal and fast-mode I2C interfaces, two time-of-day alarms, an oscillator stop flag, programmable square-wave outputs that default to 32kHz on power-up, and operating voltages ranging from 1.8V to 5.5V. The Renesas 1338 real-time clock IC includes a 56-Byte battery-backed non-volatile RAM for data storage.
A real-time clock IC (RTC IC) is an integrated circuit that keeps track of the current time and date, typically counting seconds, minutes, hours, day, month, and year with leap-year compensation. Although the term often refers to the devices in personal computers, servers and embedded systems, real-time clock ICs are present in almost any electronic device which needs to keep accurate time. Most of Renesas' real-time clocks use an external crystal oscillator, but some contain an integrated oscillator to simplify the circuit and reduce the bill-of-materials (BOM). Most often, the oscillator's frequency is 32.768kHz, or, exactly 2^15 cycles per second; making it a convenient rate to use with binary counter circuits.
Interface |
Alarms (#) |
Supply Voltage Vcc (Min) (V) |
Battery Backup |
Battery Seal |
CPU Supervisory Function POR |
Crystal Frequency Trimming |
Frequency Out Pin |
Battery Current (nA) |
Time Keeping Current (µA) |
SRAM |
Selectable Frequency Output |
Oscillator Compensation |
TRIP Voltage for POR |
Accuracy |
Other Functions |
Price (USD) | 1ku |
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Part Number | |||||||||||||||||
Real-Time Clock With I2C Serial Interface | I2C | 2 | 1.8 | No | No | No | No | No | 300 | 0.9 | 1 | ±10 ppm | 1.75 | ||||
Real-Time Clock With Battery Backed Non-Volatile RAM | I2C | 0 | 1.8 | No | No | No | No | No | 300 | 1.4 | 56 Bytes | 1 | ±20 ppm | 1.683 | |||
Real-Time Clock With Serial I2C Interface | I2C | 2 | 2 | No | No | No | No | No | 300 | 1.4 | 1 | ±20 ppm | 1.683 | ||||
I2C Real Time Clock with Battery Backup Low Power RTC with Battery ReSeal™ Function | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 800 | 1.6 | 1 | -94 to +140 | 1.683 | ||||
Real Time Clock with Embedded Crystal, ±5ppm Accuracy | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 1000 | 3.5 | 128 Bytes | 15 | -336 to +337 | 6 Select VTRIP Levels | ±5 ppm | Battery Status Monitor, Battery Switchover Time Stamp and more... |
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Low Power RTC with Battery-Backed SRAM and Embedded Temp Compensation ±5ppm with Auto Day Light Saving | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 1000 | 3.5 | 128 Bytes | 15 | -336 to +337 | 6 Select VTRIP Levels | ±5 ppm | Battery Status Monitor, Battery Switchover Time Stamp and more... |
3.012 |
Low Power RTC with Battery Backed SRAM, Integrated ±5ppm Temperature Compensation and Auto Daylight Saving | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 1000 | 3.5 | 128 Bytes | 15 | -336 to +337 | 6 Select VTRIP Levels | ±5 ppm | Battery Status Monitor, Battery Switchover Time Stamp and more... |
4.2 |
Low Power RTC with Battery Backed SRAM, Integrated ±5ppm Temperature Compensation and Auto Daylight Saving | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 1000 | 3.5 | 128 Bytes | 15 | -336 to +337 | 6 Select VTRIP Levels | ±5 ppm | Battery Status Monitor, Battery Switchover Time Stamp and more... |
4.2 |
Low Power RTC with Battery Backed SRAM, Integrated ±5ppm Temperature Compensation and Auto Daylight Saving | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 1000 | 3.5 | 128 Bytes | 15 | -336 to +337 | 6 Select VTRIP Levels | ±5 ppm | Battery Status Monitor, Battery Switchover Time Stamp and more... |
4.822 |
Real Time Clock/Calendar with I2C Bus™ and EEPROM | I2C | 2 | 2.7 | Yes | Yes | No | Yes | Yes | 850 | 5 | 512x8-Bit EEPROM | 3 | -64 to +110 | 2.234 | |||
Real Time Clock/Calendar with I2C Bus™ and EEPROM | I2C | 2 | 2.7 | Yes | Yes | No | Yes | Yes | 850 | 5 | 512x8-Bit EEPROM | 3 | -64 to +110 | 2.234 | |||
Low Cost and Low Power I2C Real Time Clock/Calendar with Alarm Function and Dual IRQ Pins | I2C | 2 | 1.4 | No | No | Yes | No | Yes | 0.5 | 4 | Dual Alarms, Dual IRQs | 1.471 | |||||
Low Cost and Low Power I2C Bus™ Real Time Clock/Calendar Low Power and Low Cost RTC with Alarm Function | I2C | 2 | 1.4 | No | No | No | No | Yes | 0.5 | 4 | Dual Alarms | 1.471 | |||||
I2C Real Time Clock/Calendar, Low Power RTC with Battery-Backed SRAM | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 400 | 1.2 | 2 Bytes | 15 | -94 to +140 | Yes | 1.909 | ||
Low Power RTC with Battery Backed SRAM and Event Detection | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 400 | 1.2 | 2 Bytes | 15 | -94 to +140 | Yes | Event Detect | 2.178 | |
Low Power RTC with Battery Backed SRAM and Event Detection | I2C | 1 | 2.7 | Yes | Yes | No | Yes | Yes | 400 | 1.2 | 2 Bytes | 15 | -94 to +140 | Event Detect, Time Stamp | 2.206 |