Ultra-Low-Power Real Time Clock with Integrated Power Switch

The MAX31334 ultra-low-power, real-time clock (RTC) is a time-keeping device that consumes only 70nA timekeeping current. It features an integrated high-side power pass switch that enables ultra-low-power idle modes on duty-cycled applications by disconnecting power to other devices on the system. The power switch on/off durations can be controlled by periodic interrupt sources such as countdown timer (programmable from 100ms to 1hr) and alarms (1s resolution). The power switch can also be controlled by an external interrupt (from a pushbutton, for example) on the DIN pin. The MAX31334 supports a wide range of crystals with any loading (CL) spec which broadens the pool of usable crystals for this device. This device is accessed through an I2C serial interface. An integrated power-on reset function ensures deterministic default register status upon power-up.

The device also features a backup supply pin (VBAT) and automatically switches over to this supply when the main supply (VCC) drops below the programmed threshold voltage. Other features include two time-of-day alarms, interrupt outputs, a programmable square-wave output, event detection input with timestamping (32-byte timestamp registers double as RAM storage), a serial bus timeout mechanism.

The digital Schmitt trigger input (DIN) can also be used to record timestamps and/or assert an interrupt on a falling/rising edge of the DIN signal. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. A 1/128 seconds register is available for a sub-second timestamp resolution. 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/12-hour format.

The MAX31334 is available in lead (Pb)-free/RoHS compliant, 12-bump, 1.5mm x 2mm WLP with 0.5mm pitch, as well as a 12-pin 3mm x 3mm TDFN package.

The device supports the -40°C to +85°C extended temperature range.

Applications

* Electronic Shelf Label

* Ultra-low-power IoT Modules

* Medical Wearables

* Temperature Loggers

* Asset Tracking

* Battery-Powered Devices

* Ultra-Low-Power Real Time Clock

* 70nA Timekeeping Current

* 1.1V to 5.5V Timekeeping Voltage Range

* Automatic Switchover to Backup Supply on Power Failure

* Trickle Charger for External Supercapacitor

* Integrated Power Switch with State Machine Increases System Battery Life

* Up to 500mA Continuous Current

* Ultra-Low 57mΩ On-Resistance

* Wakeup on Periodic Interrupt—Countdown Timer (100ms to 1hr) and Alarms (1s Resolution)

* Wakeup on External Interrupt, Like Pushbutton