DS1302SN+T&R

Overview

The DS1302SN+T&R is a Real-Time Clock (RTC) integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It provides timekeeping functions including seconds, minutes, hours, date, month, and year with leap-year compensation valid up to the year 2100. The device features 31 bytes of battery-backed static RAM for general-purpose data storage. It communicates via a simple 3-wire serial interface compatible with most microcontrollers. Operating on a supply voltage range of 2V to 5.5V, it supports an industrial temperature range from -40°C to +85°C. The component is housed in an 8-SOIC package with a width of 5.30mm.

Feature Summary

• Real-time clock/calendar with leap-year compensation valid through 2100
• 31 bytes of battery-backed NVSRAM for general-purpose storage
• Simple 3-wire synchronous serial interface (CE, I/O, SCLK)
• Programmable trickle charger for backup power source maintenance

Applications

• Embedded systems requiring precise calendar and time tracking
• Industrial control equipment operating in wide temperature environments
• Portable devices utilizing battery backup for continuous timekeeping

Procurement Notes

Verify that the specific order suffix T&R corresponds to the Tape & Reel packaging format as indicated in local product fields. Confirm the industrial temperature grade (-40°C to +85°C) matches system requirements, as commercial variants exist. Ensure compatibility with the 8-SOIC (0.209 inch width) footprint during PCB layout.

Selection Notes

Select this variant when an industrial temperature rating is required alongside surface-mount assembly. The SN designation indicates the SOIC package style with the wider 5.30mm body dimension. Verify that the microcontroller supports the required 3-wire serial protocol and can handle the TTL-compatible logic levels at the chosen supply voltage.

Part Context

This part belongs to the DS1302 series of trickle-charge timekeeping chips. The 'SN' suffix specifically denotes the industrial temperature grade (-40°C to +85°C) and the 8-pin Small Outline (SO) package with a 208-mil (5.30mm) width. The '+T&R' suffix indicates lead-free/RoHS compliance and Tape & Reel packaging.

Replacement Considerations

DS1302S+T&R: Commercial temperature grade (0°C to +70°C), same 8-SOIC package.

FAQ

How does the DS1302SN+T&R handle power switching between primary and backup sources?

The device uses dual power pins (VCC1 and VCC2). It automatically operates from the higher voltage source. If VCC2 is greater than VCC1 + 0.2V, VCC2 powers the chip; otherwise, VCC1 powers it.

What crystal specifications are required for the DS1302SN+T&R oscillator?

An external 32.768kHz quartz crystal is required. The internal oscillator is designed for a crystal with a specified load capacitance (CL) of 6pF.

Can the DS1302SN+T&R operate in both 12-hour and 24-hour formats?

Yes, the clock operates in either 12-hour or 24-hour format. Bit 7 of the hours register selects the mode, with bit 5 serving as the AM/PM indicator in 12-hour mode.