DP8573AN

Overview

The DP8573AN is a real-time clock (RTC) from Texas Instruments, implemented in low voltage silicon gate microCMOS technology. It provides a full-function calendar and clock with 12/24 hour modes, day of week, and leap year support in BCD format. The device features a parallel interface, appearing as a contiguous block of 32 bytes including control registers, counters, and RAM. It operates on a single 5V supply (4.5V to 5.5V) or dual supplies with battery backup. Key electrical parameters include a quiescent supply current of 250 µA at 5V and standby battery leakage of 1.5 µA max at 5.5V. It includes power fail detection, automatic time save logic, and three interrupt types: periodic, alarm, and power fail.

Feature Summary

• Full-function RTC/calendar with 12/24 hour modes, day of week, and leap year counters in BCD format.
• Integrated power fail logic with automatic switch to battery supply (VBB) when VCC drops below VBB.
• On-chip interrupt structure supporting Periodic, Alarm/Compare, and Power Fail interrupts.
• Parallel bus interface organized as a 32-byte memory block for easy microprocessor integration.

Applications

• Microprocessor-based systems requiring multi-tasking synchronization.
• Data logging applications needing precise time/date stamping.
• General time-of-day and date information systems.
• Battery-backed embedded systems requiring low standby power.

Procurement Notes

Verify the package type matches the application requirements; the 'AN' suffix denotes a 24-pin Plastic Dual-In-Line (PDIP) package. Confirm that the host system supports the parallel interface timing specifications, specifically read/write strobe widths and address hold times. Ensure the design accounts for the required external 32.768 kHz crystal and load capacitors for the internal oscillator. Check if the single-supply mode is sufficient or if battery backup via the VBB pin is needed for the specific use case.

Selection Notes

Select the DP8573AN when a parallel interface RTC is required with integrated power fail protection and automatic time saving capabilities. It is suitable for systems operating within the -40°C to +85°C temperature range. Consider the DIP-24 package for through-hole mounting. If I2C or SPI interfaces are preferred, other RTC models should be evaluated. Ensure the system can provide the necessary 32.768 kHz crystal and capacitors for the parallel resonant oscillator.

Part Context

The DP8573A series is part of National Semiconductor's (now Texas Instruments) legacy real-time clock portfolio. The DP8573AN specifically refers to the PDIP-24 variant. It is designed to replace older discrete clock solutions by integrating the oscillator, prescaler, and control logic into a single CMOS chip. The device simplifies system design by handling power fail detection and battery switching internally.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. The DP8573AV/NOPB is a PLCC-28 variant of the same functional device. Direct pin-to-pin replacement with other manufacturers' parts requires careful verification of register maps and timing characteristics due to the proprietary parallel interface architecture.