MAXIM DS1672U-33+

The DS1672 incorporates a 32-bit counter and power-monitoring functions. The 32-bit counter is designed to count seconds and can be used to derive time-of-day, week, month, and year by using a software algorithm. A precision, temperature-compensated reference and comparator circuit monitors the status of VCC. When an out-of-tolerance condition occurs, an internal power-fail signal is generated that forces the reset to the active state. When VCC returns to an in-tolerance condition, the reset signal is kept in the active state for a period of time to allow the power supply and processor to stabilize. The DS1672 provides a 32-bit counter that increments once-per-second. The counter data is accessible via an I²C serial interface. A precision, temperature-compensated, voltage reference and comparator circuit monitors VCC. When VCC drops below VPF, RST becomes active and the interface is disabled to prevent data corruption. The device switches to the backup supply input, which maintains oscillator and counter operation while VCC is absent. When VCC rises above VPF, RST remains low for a period of time (tRPU) to allow VCC to stabilize. Communications to and from the DS1672 occur serially over a I²C, bidirectional bus. The DS1672 operates as a slave device on the I²C bus. Access is obtained by implementing a START condition and providing a device identification code followed by a register address. Subsequent registers can be accessed sequentially until a STOP condition is executed.

• 32-Bit Counter
• I²C Serial Interface
• Automatic Power-Fail Detect and Switch Circuitry
• Power-Fail Reset Output
• Low-Voltage Oscillator Operation (1.3V min)
• Trickle-Charge Capability
• Underwriters Laboratories (UL) Recognized
• -40°C to +85°C Operating Range