BQ4845YP-A4

Overview

The BQ4845YP-A4 is a low-power microprocessor peripheral integrating a real-time clock, 100-year calendar, and CPU supervisor in a 28-pin plastic DIP package. It operates on a +5V supply with a minimum voltage of 4.75V and supports an industrial temperature range of -40°C to +85°C. The device features a parallel interface for direct connection to system buses, providing 16 bytes of nonvolatile RAM control via an external SRAM switch. Key electrical characteristics include less than 500nA backup current and a programmable watchdog timer.

Feature Summary

• Integrates a real-time clock counting seconds through years in BCD format with automatic leap year adjustment.
• Includes a CPU supervisor with power-fail interrupt warning and microprocessor reset valid down to VSS.
• Features an independent watchdog timer with programmable time-out periods ranging from 1.5s to 3s.
• Provides on-chip battery-backup switchover circuitry to maintain external SRAM data during power loss.

Applications

• Fax machines
• Copiers
• Industrial control systems
• Point-of-sale terminals
• Data loggers

Procurement Notes

Verify the specific suffix 'Y' indicates a 10% voltage tolerance variant compared to the standard 5% version. Confirm the 'P' designation corresponds to the 28-pin plastic DIP package. Check for the 'A4' environmental compliance marking against current RoHS directives. Ensure the industrial temperature grade (-40°C to +85°C) matches the application requirements.

Selection Notes

Select this component when a parallel interface RTC with integrated CPU supervision is required. The BQ4845YP-A4 is suitable for systems needing a 100-year calendar and nonvolatile memory control without serial bus overhead. Consider the 28-pin DIP form factor for through-hole mounting constraints. Evaluate the need for the specific 10% voltage tolerance if operating near the lower supply limits.

Part Context

This part belongs to the bq4845 family of parallel real-time clocks with CPU supervisors. The 'Y' suffix denotes a 10% voltage tolerance specification, while 'P' identifies the 28-pin plastic dual in-line package. The 'A4' suffix typically indicates lead-free and halogen-free material composition compliant with specific environmental standards.

Replacement Considerations

Direct pin-compatible replacements within the same family include the bq4845P (5% voltage tolerance) or bq4845YS-A4 (SOIC package). Cross-vendor alternatives such as the Xicor X1288 or Intersil X1227 offer similar functionality but utilize different 2-wire serial interfaces rather than parallel connections.