DS1558W-TRL

Real Time Clock Overview

The DS1558W-TRL is a year 2000-compliant real-time clock/calendar with an integrated watchdog timer, power-on reset, battery monitor, and NV SRAM controller. It operates at 3.3V within the -40°C to +85°C range. The device maps RTC registers into the top 16 locations of the static RAM address space, accessed via a byte-wide parallel interface. It features BCD-coded timekeeping with automatic leap-year compensation valid until 2100. Key electrical parameters include a typical active supply current of 4mA at 3.3V and a battery standby current of less than 0.5µA with the oscillator on. The package is a 48-pin TQFP.

Real Time Clock Feature Summary

• Integrated Real-Time Clock (RTC), Power-Fail Control Circuit, and NV RAM Controller
• Clock Registers Accessed Identically to Static RAM in Top 16 Locations
• Programmable Watchdog Timer and RTC Alarm with Interrupt Output
• BCD-Coded Year, Month, Date, Day, Hours, Minutes, Seconds with Automatic Leap-Year Compensation

Real Time Clock Applications

• Systems requiring precise timekeeping with non-volatile data retention
• Applications needing CPU watchdog monitoring via programmable timeout
• Battery-backed systems requiring seamless power switchover protection

Real Time Clock Procurement Notes

Verify the specific ordering suffix corresponds to the tape-and-reel packaging format required for automated assembly. Confirm that the 3.3V voltage variant matches the system power supply rails. Ensure compatibility with the 48-TQFP footprint during PCB layout review. Check for any manufacturer errata related to this specific revision before finalizing the design.

Real Time Clock Selection Notes

Select the DS1558W-TRL when a 3.3V operating voltage is required instead of the 5.0V DS1558Y variant. This part integrates both the RTC and NV SRAM control, reducing component count compared to discrete solutions. Ensure the external crystal meets the specified 6pF load capacitance for accurate timing. Verify that the parallel interface timing requirements align with the host processor's capabilities.

Real Time Clock Part Context

This component belongs to the DS1558 family of watchdog clocks with NV RAM control. The 'W' designation indicates the 3.3V version, while 'Y' denotes the 5.0V version. The '-TRL' suffix specifies the reel packaging format. It serves as a combined timekeeping and memory management solution for embedded systems requiring high reliability and low power consumption in battery-backed scenarios.

Real Time Clock Replacement Considerations

The DS1558W+ is the lead-free/RoHS-compliant equivalent of the DS1558W. For 5.0V applications, the DS1558Y series offers similar functionality but requires different supply voltages. Direct pin-compatible replacements within the same family include the DS1558Y-TRL for 5V systems.