AS1801-BTDT

Overview

The AS1801 is an ultra-low power serial real-time clock (RTC) with a trickle charger, manufactured by Austria Micro. It provides timekeeping for seconds, minutes, hours, day, date, month, and year in BCD format, supporting both 12-hour and 24-hour modes with automatic leap-year compensation up to the year 2100. The device operates on a supply voltage of 1.8V to 3.6V for VCC and 0.9V to 3.6V for battery backup. Timekeeping current is typically 500nA at 1.5V. It features dual alarms, a programmable square-wave output, and frequency trimming capabilities via I²C interface.

Feature Summary

• Ultra-low power consumption with standby current as low as 400nA at 1.5V
• Integrated trickle charger for battery or supercapacitor backup management
• Dual programmable time-of-day alarms and interrupt/square-wave output
• Oscillator frequency trimming with 3.81 ppm steps over 8-second intervals and 5.8 ppm steps over 2-day periods

Applications

• Handheld devices such as GPS units and POS terminals
• Consumer electronics including set-top boxes and digital recorders
• Medical implements like glucometers and medicine dispensers
• Telecommunications equipment such as routers, switches, and servers

Procurement Notes

Verify the package type matches the required footprint, specifically the 8-UFDFN Exposed Pad (8-TDFN 2x2). Confirm the operating temperature range requirements align with the specified -40°C to +85°C industrial grade. Ensure the design supports the I²C bus protocol speeds up to 400 kHz for fast mode operation.

Selection Notes

Select this component when ultra-low battery drain is critical, particularly for applications requiring long-term backup without primary power. Consider the integrated trickle charger if using rechargeable backup sources like supercapacitors, but disable it for standard lithium batteries. Verify that the external crystal load capacitance requirement of 6pF matches the selected resonator specifications.

Part Context

The AS1801 belongs to the family of serial real-time clocks designed for battery-operated systems. It distinguishes itself from basic RTCs by including a programmable trickle charger and advanced frequency trimming registers to compensate for crystal drift over temperature and aging, enhancing accuracy without external calibration components.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation.