Real-Time Clock Supports Timekeeping Current of 150nAApril 29, 2019 by Scott McMahan
Maxim Integrated introduced the MAX31342 low-current, real-time clock (RTC). It is a time-keeping device that provides an extremely low timekeeping current that allows longer life from a power supply. The MAX31342 supports 6pF high-ESR crystals, which broaden the pool of usable crystals for the devices. An I2C serial interface provides access to the device. Upon power-up, an integrated power-on reset function ensures deterministic default register status. (See functional diagram above).
Typical applications for the RTC include medical, wearables, point-of-sale (POS), telematics, portable instruments, portable audio, and power meters.
Other features a serial bus timeout mechanism, two time-of-day alarms, interrupt outputs, and a programmable square-wave output. The clock/calendar provides seconds, minutes, hours, day, date, month and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in 24-hour mode.
The MAX31342 also includes an input for synchronization. When a reference clock (such as a 32kHz, 50Hz/60Hz Power Line, GPS 1PPS) is present at the CLKIN pin and the enable external clock input bit (ECLK) is set to 1, the MAX31342 RTC is frequency-locked to the external clock and the clock accuracy is determined by the external source.
Maxim says that the RTC can increase battery life. The device provides a timekeeping current of just 150nA. It can work with a wide range of external crystals with CL = 6pF and ESR up to 100kΩ for a minimal current draw.
The RTCs have integrated load capacitors for the crystal oscillator. This integration combined with the compact size of 1mm x 2mm, 8-Bump WLP with 0.5mm pitch package help the RTC save PCB space.
The RTC has an operating voltage range of 1.6V to 3.6V, and it features a countdown timer with a repeat function. The device can operate in temperatures from -40°C to +85°C.
Integrated protection features include Power-On Reset for default configuration and lockup-free operation with bus timeout.
Features and Benefits
- Increases Battery Life
- 150nA Timekeeping Current
- Wide Range of External Crystals with CL = 6pF and ESR up to 100kΩ for Minimal Current Draw
- Provides Flexible Configurability
- Programmable Square Wave Output for Clock Monitoring
- Saves Board Space
- Integrated Load Capacitors for Crystal Oscillator
- 1mm x 2mm, 8-Bump WLP with 0.5mm Pitch
- Value Add Features for Ease of Use
- +1.6V to +3.6V Operating Voltage Range
- Countdown Timer with Repeat Function
- Integrated Protection
- Power-On Reset for Default Configuration
- Lockup-Free Operation with Bus Timeout