SPI RTC with onboard NVSRAM and trickle charger
The Maxim Integrated DS1305E+T&R is a serial real-time clock/calendar that communicates over SPI, carrying 96 bytes of NVSRAM for user data that survives a main power loss. It includes a trickle-charger for a backup battery or supercap, plus alarm and leap-year compensation. The 2 V to 5.5 V supply range and 0°C to 70°C operating temperature suit it for indoor equipment, instrumentation, and embedded controllers where a battery-backed timebase and a small scratchpad are needed on one SPI bus.
Timekeeping current and battery life
Timekeeping current ranges from 25.3 µA to 81 µA depending on supply voltage.
20-TSSOP footprint and surface-mount assembly
The 20-TSSOP package (4.40 mm body width) is a standard fine-pitch SOIC footprint. It mounts on the board alongside the MCU and passives, with no special handling beyond normal SMT reflow. The Tape & Reel option suits automated pick-and-place; the Cut Tape variant works for prototypes or small runs.
Active lifecycle and ROHS compliance
The DS1305E+T&R carries an Active product status and ROHS3 compliance. No end-of-life notice or last-time-buy window is in effect. It can be specified into new designs without an obsolescence clock, and the ROHS3 rating covers the current EU exemption scope.