DS1302S/T&R

Overview

The DS1302S/T&R is a Real-Time Clock (RTC) and calendar integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It provides seconds, minutes, hours, date, month, day of the week, and year information with leap-year compensation valid up to the year 2100. The device features a simple 3-wire serial interface compatible with TTL logic levels at VCC = 5V. It includes 31 bytes of battery-backed static RAM for general-purpose data storage. Electrical specifications include a supply voltage range of 2.0V to 5.5V, timekeeping current ranging from 0.3µA to 1µA depending on voltage, and an operating temperature range of 0°C to +70°C. The component is housed in an 8-SOIC package.

Feature Summary

• Real-time clock/calendar with leap-year compensation valid through 2100
• 31-byte battery-backed static RAM for non-volatile data storage
• Simple 3-wire synchronous serial interface (CE, I/O, SCLK)
• Programmable trickle charger for backup battery or supercapacitor charging

Applications

• Portable instruments requiring precise timekeeping
• Telecommunications equipment
• Faxes and computer peripherals

Procurement Notes

Verify the specific suffix configuration against the manufacturer's ordering guide. The 'T&R' designation indicates Tape & Reel packaging. Confirm that the commercial temperature grade (0°C to +70°C) meets system requirements, as industrial variants (-40°C to +85°C) exist under different part numbers such as DS1302SN+.

Selection Notes

Select this component when a low-pin-count RTC solution is required. Ensure the microcontroller supports the synchronous 3-wire protocol. Verify that the external 32.768kHz crystal load capacitance matches the internal oscillator design (typically 6pF). Consider the trickle charger settings if using a rechargeable backup source connected to VCC1.

Part Context

The DS1302 series serves as a successor to the DS1202, adding dual power pins and programmable trickle charging capabilities. The 'S' suffix denotes the 8-pin SO (208 mils) surface-mount package. The 'T&R' suffix specifies the reel packaging format for automated assembly processes.

Replacement Considerations

For industrial temperature grades (-40°C to +85°C), consider the DS1302SN+ (8-Pin SO, 208 mils) or DS1302ZN+ (8-Pin SO, 150 mils). For DIP packages, the DS1302+ or DS1302N+ are available equivalents.