SPI RTC with 96B NVSRAM and trickle-charger
The DS1305E+ is a full-featured real-time clock (RTC) from Analog Devices, providing seconds, minutes, hours, day, date, month, and year information with leap-year compensation through 2100. It communicates over a 4-wire SPI interface and includes 96 bytes of NVSRAM for user data storage. On-chip features include a programmable alarm, a trickle-charger for backup battery management, and automatic leap-year correction. The timekeeping current ranges from 25.3 µA to 81 µA depending on supply voltage (2V to 5V), making it suitable for battery-backed applications.
Supply voltage and temperature grade
The DS1305E+ operates from a single 2V to 5.5V supply and supports a separate battery backup input (VBAT) with the same voltage range. The trickle-charger feature allows a super-cap or rechargeable lithium cell to be charged from the main supply, maintaining the timekeeping and NVSRAM contents during main power loss. The timekeeping current varies with voltage and temperature — at 2V the typical draw is 25.3 µA, rising to 81 µA at 5V.
The supplier device package is 20-TSSOP.