BQ4802YDSH - Parallel RTC with CPU Supervisor | Texas Instruments
MPN: BQ4802YDSH ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.82 | $6.82 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
BQ4802YDSH Overview
A real-time clock is a clock-and-timing IC that maintains calendar information independently of the system processor. The BQ4802YDSH sits in the system timing hierarchy as a parallel RTC beneath the processor bus and above the backup-battery and SRAM subsystem. Its calendar and supervision functions are useful in industrial controllers, embedded systems, test equipment, data loggers, and systems requiring time stamps or reliable nonvolatile state.
The supplied product information identifies the BQ4802Y, Y2K-compliant parallel RTC with CPU supervisor and external NVSRAM control. Listed features include alarm, daylight-saving time, leap-year handling, a supervisor, and a watchdog timer. The package is identified as 28-SOIC, with a width of 0.345 inch and a stated width of 8.77 mm in distributor listings. The Y designation and DSH package suffix are retained exactly as supplied.
The parallel interface is intended for systems that can accommodate the RTC's 28-pin arrangement and provide the required control signals. Because the supplied excerpts do not include the complete timing table, electrical limits, register map, or absolute maximum ratings, those parameters remain to be confirmed from the manufacturer datasheet before release to production.
Typical design use includes supervising a processor reset line, timestamping events, scheduling alarms, preserving external SRAM contents during a power interruption, and coordinating watchdog activity. The CPU supervisor and watchdog functions are particularly useful when a controller must recover predictably after brownout or firmware lockup conditions.
For layout, place the device close to the processor and backup circuitry while preserving the package pin arrangement and decoupling path specified by the manufacturer. Verify oscillator, backup-battery, reset, and SRAM interfaces against the complete datasheet; the available search excerpts do not provide every electrical value required for a production schematic.
This page consolidates the supplied distributor metadata, package information, and application context. It also distinguishes verified facts from parameters that still require datasheet confirmation rather than filling gaps with guessed values.
Drop-in alternatives for BQ4802YDSH — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
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Request AlternativesBQ4802YDSH Specifications
| Product Type | Parallel real-time clock with CPU supervisor |
| Supply Voltage | 5 V |
| Calendar Compliance | Y2K-compliant |
| Clock/Calendar Memory | 16 bytes |
| Interface Type | Parallel |
| Package | 28-SOIC |
| Package Width | 0.345 inch |
| Package Width, Distributor Listing | 8.77 mm |
| Backup Support | SNAPHAT sockets |
| NVSRAM Support | External SRAM nonvolatile-memory backup |
| Alarm Feature | Yes |
| Daylight-Saving Feature | Yes |
| Leap-Year Handling | Yes |
| CPU Supervisor | Yes |
| Watchdog Timer | Yes |
| Pin Count | 28 pins |
BQ4802YDSH 8.77 mm Pin Configuration Guide
Pin configuration for BQ4802YDSH (8.77 mm package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for BQ4802YDSH.
Refer to the datasheet for full pin configuration.
Typical Applications
BQ4802YDSH is suitable for 7 applications: Embedded Processor Supervision, Industrial Data Logging, Power-Fail-Aware SRAM Retention, Programmable Alarm and Scheduling, Instrumentation and Test Systems, Embedded Networking Equipment, Battery-Backed Controller Module.
Embedded Processor Supervision
The BQ4802YDSH is suited to embedded processor boards that need timekeeping combined with fault supervision. Its verified CPU-supervisor and watchdog functions can help a host recover from processor lockups or abnormal operating states, while the parallel interface keeps the timing device accessible to a compatible bus controller. The 5 V VCC requirement and 28-SOIC footprint should be included in the motherboard power and layout plan. Exact reset polarity, watchdog timing, and register behavior must be confirmed from the manufacturer datasheet.
Recommended
Industrial Data Logging
Industrial data loggers can use the BQ4802YDSH to maintain calendar time for events, alarms, and scheduled records. The verified Y2K-compliant parallel clock/calendar and 16-byte memory provide a dedicated timing function, while the CPU supervisor and watchdog support more reliable controller behavior. In a data logger, place the RTC where its 28-SOIC footprint and 5 V supply are accessible to the control logic. Exact timestamp resolution and register access timing remain datasheet-dependent.
Recommended
Power-Fail-Aware SRAM Retention
The BQ4802YDSH is a timing choice when an embedded system must coordinate external SRAM retention during a power interruption. Its verified external SRAM nonvolatile-memory backup-control feature, together with SNAPHAT socket support, allows the design to associate the RTC with a backup source. The implementation must verify battery chemistry, backup-current limits, write-control logic, and power-fail timing from the complete datasheet. The available excerpts do not provide capacitor values or retention-duration specifications.
Recommended
Programmable Alarm and Scheduling
Use the BQ4802YDSH when an embedded controller needs scheduled events based on calendar time. The verified alarm, daylight-saving, and leap-year features provide calendar-aware timing functions that can complement a host scheduler or trigger external equipment. The parallel interface allows the controller to read and update time through a dedicated bus arrangement. Because alarm resolution, interrupt behavior, and electrical timing are not included in the supplied excerpts, confirm them in the manufacturer datasheet before setting timing tolerances.
Recommended
Instrumentation and Test Systems
The BQ4802YDSH fits instrumentation and test systems that require traceable calendar events alongside processor supervision. Its 16-byte clock/calendar memory, alarm function, watchdog, and CPU supervisor provide a consolidated timing-and-monitoring block for an embedded instrument. The 28-SOIC package simplifies use on a conventional through-hole-style SMD board footprint, while the 5 V supply must match the instrument rail. Verify signal levels, timing margins, and package details against the official datasheet.
Recommended
Embedded Networking Equipment
Networked embedded equipment can use the BQ4802YDSH for local timestamping, watchdog supervision, and predictable recovery from controller faults. The verified CPU supervisor and watchdog functions complement a network processor or embedded controller, while calendar support helps associate events with a date and time. The 5 V supply and parallel 28-SOIC interface must be checked against the host processor requirements. No network-specific protocol or timestamp resolution is supplied by the verified excerpts.
Recommended
Battery-Backed Controller Module
The BQ4802YDSH is appropriate for a battery-backed controller module where calendar information and external SRAM retention must survive a main-power interruption. The verified SNAPHAT socket support and external SRAM backup-control description provide the basis for a retention architecture, while the CPU supervisor and watchdog add system-health monitoring. The backup battery, regulator, and SRAM write path must be designed from the complete electrical specifications. Current draw and retention duration are not available in the supplied excerpts.
Recommended
Recommended Products Summary
Engineering reference data for BQ4802YDSH — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Package | 28-SOIC |
| Brand | Texas Instruments |
| Supply Voltage | 5 V |
| Interface | Parallel |
| Clock/Calendar Memory | 16 bytes |
| Calendar Compliance | Y2K-compliant |
| CPU Supervisor | Yes |
| Watchdog Timer | Yes |
| External SRAM Backup Control | Yes |
| Alarm | Yes |
Key Differentiators
- Integrated supervision beyond basic timekeeping (vs Generic parallel RTC)
- External SRAM retention-control integration (vs RTC without SRAM backup control)
- Calendar-oriented feature set (vs Simple counter or calendarless timer)
Design Notes
Design the BQ4802YDSH supply path around the verified 5 V VCC requirement and keep the RTC backup path separate from the normal system rail according to the manufacturer application guidance. Because the supplied excerpts do not provide operating-voltage limits, quiescent current, backup current, or capacitor values, do not finalize the regulator or decoupling network without the official datasheet and power-budget calculations.
Place the 28-SOIC footprint so that the RTC, backup-battery connection, external SRAM interface, and host processor bus have short, controlled routes. Confirm pin numbering from the manufacturer drawing before routing; the supplied search results identify the package but do not provide a complete pin table. Keep sensitive timing and backup-control traces away from high-current switching nodes where practical.
Do not treat the BQ4802YDSH as a generic time-only RTC. Its value comes from the combination of calendar timing, CPU supervision, watchdog monitoring, alarm handling, and external SRAM backup control. Verify reset polarity, watchdog limits, backup-battery requirements, and SRAM write timing in the datasheet before connecting the device to a new processor platform.
The available distributor pages provide package and feature summaries but not a complete electrical specification set. Avoid importing typical values from another RTC or from a different BQ4802 package variant. Check the exact BQ4802YDSH ordering code, operating-temperature range, absolute maximum ratings, oscillator details, and timing characteristics against the manufacturer datasheet.
Compliance Information
The supplied search results identify the manufacturer, package, features, and commercial sources but do not provide verified RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declarations.
