DS1501WSN

Real Time Clock Overview

The DS1501WSN is a Y2K-compliant real-time clock/calendar IC manufactured by Analog Devices Inc./Maxim Integrated. It features a parallel interface, 256 bytes of NVSRAM, and operates at +3.3V with a temperature range of 0°C to +70°C. The device provides automatic leap-year compensation up to the year 2100, a programmable watchdog timer, and an RTC alarm. Key electrical parameters include a maximum active supply current of 10mA and a standby current of 4mA at 3.3V. It utilizes a 32.768kHz crystal for timekeeping and includes power-fail detection with battery backup switching.

Real Time Clock Feature Summary

• Y2K-Compliant RTC with automatic leap-year correction valid through 2100
• Integrated 256-byte battery-backed NVSRAM
• Programmable watchdog timer and day-of-week/date alarm
• +3.3V operation with precision power-on reset and battery voltage-level indicators

Real Time Clock Applications

• Remote Systems
• Battery-Backed Systems
• Telecom Switches
• Office Equipment
• Consumer Electronics

Real Time Clock Procurement Notes

Verify component authenticity and datasheet revision compatibility before integration. Confirm that the specific package variant matches the design requirements. Check for any known errata associated with this manufacturing batch. Ensure proper handling procedures are followed during assembly to maintain reliability.

Real Time Clock Selection Notes

Select the DS1501WSN for applications requiring a standalone RTC with integrated memory and +3.3V logic levels. Ensure the system design accommodates the required parallel interface signals. Verify that the external crystal meets the specified load capacitance requirements (6pF or 12.5pF) for optimal accuracy.

Real Time Clock Part Context

The DS1501WSN belongs to the DS1501/DS1511 family of Y2K-compliant real-time clocks. It is functionally similar to other variants in the series but is distinguished by its specific voltage rating (+3.3V), operating temperature range (0°C to +70°C), and surface-mount SOIC packaging.

Real Time Clock Replacement Considerations

Direct replacements within the same family include DS1501WE+ and DS1501WEN+. Verify pinout compatibility and ensure that the substitute part supports the required +3.3V supply voltage and parallel interface timing specifications.

Real Time Clock FAQ

How does the DS1501WSN handle data retention during power failure?

When VCC drops below the power-fail trip point, the device automatically switches to battery backup via the VBAT or VBAUX pins. All inputs become don't cares, outputs go to high-Z, and the internal clock registers and SRAM are maintained by the battery.

What is the purpose of the Kickstart (KS) input?

The KS input is an active-low pin used to wake up a system from an external event, such as a key closure. It requires a pullup resistor connected to VBAUX when not in use.

Can the DS1501WSN operate with an external oscillator?

Yes, an external 32.768kHz oscillator can drive the DS1501. In this configuration, the X1 pin is connected to the external signal, and the X2 pin must be left floating.