BQ4802LYDSH - Parallel RTC with CPU Supervisor | Texas Instruments
MPN: BQ4802LYDSH ✓ ActiveBQ4802LYDSH Overview
A real-time clock, or RTC, is a clock-and-calendar integrated circuit that maintains time independently of the system processor. The broader hierarchy is RTC → clock and timing IC → timing and control semiconductor. Unlike a simple counter, this parallel-interface RTC also provides Y2K-compliant calendar functions, allowing embedded systems to preserve date information across power loss and restart operations.
The BQ4802LYDSH’s principal features are its parallel real-time-clock interface, integrated CPU supervisor, external SRAM backup control, 3 V VCC operation, and 28-pin SOIC construction. Its SNAPHAT-socket-compatible arrangement distinguishes it from conventional soldered SOIC packages and supports applications requiring removable backup-battery retention. The package is identified in verified distributor data as 28-SOIC with a 0.345-inch, 8.77 mm body width.
Technically, the device combines two closely related embedded-system functions. Its RTC section tracks calendar and clock information through a parallel host interface, while the CPU supervisor can assist a system in recovering from unstable power conditions. The external SRAM nonvolatile-memory control function provides a mechanism for retaining selected SRAM contents when backup power is available. Detailed timing accuracy, voltage thresholds, current consumption, and electrical limits are not present in the supplied verified dataset.
Typical uses include industrial controllers, embedded instruments, data-acquisition equipment, and computer systems requiring a host-readable clock, calendar, reset supervision, and backup retention. The SNAPHAT-compatible package can also support designs in which the backup battery and socket must be serviceable. Its parallel interface is particularly appropriate for systems with a microcontroller or processor bus that can accommodate the RTC address and data signals.
Designers should verify the complete pinout, electrical thresholds, backup-cell requirements, and application-specific timing behavior against the manufacturer datasheet before layout release. Care is especially important when using the external SRAM backup function because its implementation depends on the host design, retained-memory topology, and availability of backup power. The SNAPHAT socket arrangement should also be checked mechanically against the PCB footprint and battery-clearance requirements.
This page consolidates verified distributor descriptions, packaging information, pricing and availability references, compatible family members, and practical selection guidance. It distinguishes verified facts from unavailable electrical details so engineers can identify what must still be confirmed in the official BQ4802LY documentation before making a production release.
Drop-in alternatives for BQ4802LYDSH — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with BQ4802LYDSH (same form factor and footprint) — differing in Package, Package Width, Product Type, Supply Voltage.
BQ4802LYDWR
✅ Drop-In ⚠️ Specs UnverifiedContact for price
View Datasheet →BQ4802YDWR
✅ Drop-In ⚠️ Specs UnverifiedContact for price
View Datasheet →BQ4802YPWR
✅ Drop-In ⚠️ Specs UnverifiedContact for price
View Datasheet →BQ4802LYDSH Specifications
| Product Type | Parallel real-time clock and calendar IC |
| Y2K Compliance | Y2K-compliant |
| Supply Voltage | 3 V |
| Host Interface | Parallel |
| Integrated Functions | Real-time clock, CPU supervisor, external SRAM nonvolatile-memory backup |
| Package | 28-SOIC |
| Package Body Width | 8.77 mm |
| Package Height | 0.345 in |
| Terminal Count | 28 terminals |
| Terminal Form | Gull wing |
| Package Shape | Rectangular |
| Temperature Grade | Commercial |
| Backup Feature | SNAPHAT sockets and external SRAM nonvolatile-memory backup |
| Mounting Type | Surface mount |
BQ4802LYDSH rectangular Pin Configuration Guide
Pin configuration for BQ4802LYDSH (rectangular 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 BQ4802LYDSH.
Refer to the datasheet for full pin configuration.
Typical Applications
BQ4802LYDSH is suitable for 6 applications: Industrial Data-Acquisition Systems, Embedded Measurement Instruments, Networked Edge Controllers, Server and Network Appliance Timing, Battery-Backed Security and Access Systems, Automotive and Mobile Equipment Timing.
Industrial Data-Acquisition Systems
The BQ4802LYDSH fits acquisition systems that must retain timestamps and calendar records even when the main supply is interrupted. Its 3 V operation, parallel real-time-clock interface, and Y2K-compliant calendar function let a host processor read and maintain system time without reconstructing it after every reset. The integrated CPU supervisor adds an independent path for recognizing unstable power conditions, while the external SRAM backup feature can preserve selected controller data when backup power remains available. The 28-SOIC format supports conventional surface-mount assembly, although designers should verify the complete timing and threshold specifications before release.
Recommended
Embedded Measurement Instruments
The BQ4802LYDSH is suitable for laboratory and field instruments that need a persistent date, time, and reset event record. A parallel interface allows the instrument controller to access clock and calendar data directly, while the Y2K-compliant datekeeping behavior supports long-lived records. The CPU supervisor is valuable when an instrument must distinguish normal shutdown from unexpected supply interruption. If the instrument stores configuration or acquisition metadata in external SRAM, the BQ4802LYDSH’s backup-control function can assist retention, subject to confirming backup-battery behavior, timing accuracy, and electrical thresholds in the manufacturer documentation.
Recommended
Networked Edge Controllers
The BQ4802LYDSH can support edge controllers that require trustworthy local timestamps for logs, telemetry, and event histories. Its parallel clock interface works naturally with a microcontroller that can provide chip-select and data-bus control, while the 3 V supply operation aligns with common embedded rails. Y2K-compliant calendar functionality reduces date rollover concerns in long-duration deployments. The CPU supervisor provides useful power-state monitoring, and external SRAM backup control can support retention of volatile operational records when a backup source is present. Final design work must confirm signal timing, supply tolerances, and the required battery architecture.
Recommended
Server and Network Appliance Timing
The BQ4802LYDSH is applicable to embedded network appliances that need an independent clock for boot records, alarms, and maintenance logs. Its parallel RTC/calendar interface can be read by the host processor, while the CPU supervisor helps identify unexpected power loss and improve recovery behavior. The integrated external SRAM backup control is useful in legacy control architectures that still retain working state in SRAM during battery-backed operation. The 28-SOIC package and 3 V supply fit established embedded platforms, but clock drift, calibration method, alarm behavior, and supervisor thresholds must be verified before production use.
Recommended
Battery-Backed Security and Access Systems
The BQ4802LYDSH can support access-control and security equipment where event timestamps and configuration state must survive a main-power interruption. The Y2K-compliant clock and calendar provide a persistent time base, while CPU supervision offers an independent indication of supply instability. The SNAPHAT-compatible construction is particularly relevant to designs requiring a serviceable backup cell and socket. Its external SRAM backup control may also preserve selected volatile system data. Because the verified material identifies a commercial temperature grade, deployed equipment must remain within the confirmed operating range and should not infer extended-temperature suitability without checking the datasheet.
Recommended
Automotive and Mobile Equipment Timing
The BQ4802LYDSH is functionally relevant to embedded equipment requiring calendar time, reset supervision, and retained SRAM data, but its suitability for mobile or automotive use must be established carefully. The verified distributor data identifies a commercial temperature grade, while extended automotive requirements commonly depend on qualification and temperature-range details that are not present in the supplied sources. Its parallel interface, 3 V supply, and 28-SOIC package are compatible with many embedded architectures. Before using it in a vehicle or battery-powered mobile product, verify temperature limits, power-loss behavior, qualification status, and mechanical requirements directly from the manufacturer documentation.
Recommended
Recommended Products Summary
Engineering reference data for BQ4802LYDSH — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BQ4802LYDWR | BQ4802YDWR | BQ4802YPWR |
|---|---|---|---|---|
| Package | 28-SOIC | 28-SOIC | 28-SOIC | 28-SOIC |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Product Function | Parallel RTC with CPU supervisor and external SRAM backup control | BQ4802LY family parallel RTC device | BQ4802 family parallel RTC device | BQ4802 family parallel RTC device |
| Host Interface | Parallel | Parallel | Parallel | Parallel |
| Terminal Count | 28 terminals | 28 terminals | 28 terminals | 28 terminals |
Key Differentiators
- Integrated timekeeping, CPU supervision, and SRAM backup control (vs BQ4802YDWR)
- Parallel host-interface organization (vs BQ4802LYDWR)
- Serviceable backup-memory arrangement (vs BQ4802YPWR)
Design Notes
Use the manufacturer’s 28-SOIC land pattern and preserve clearance around the SNAPHAT socket and backup battery. The verified package is 0.345 inch, or 8.77 mm, wide with gull-wing terminals, but those body dimensions alone are not sufficient to define a PCB footprint. Confirm pin pitch, terminal span, courtyard, and socket orientation from the official package drawing before routing. Maintain service access for the battery if field replacement is required.
Plan the main 3 V supply and backup-power path separately because loss of main power is one of the conditions the CPU supervisor and SRAM backup functions are intended to address. Verify minimum operating voltage, backup-cell requirements, switchover behavior, and current consumption in the manufacturer datasheet; these values were not included in the supplied evidence. Avoid deriving capacitor or battery life without those verified parameters, especially for systems expected to retain volatile SRAM state during extended outages.
Do not assume that every BQ4802 order code is a drop-in substitute solely because the identifiers share a family name. Compare the ordering-information table, temperature grade, package suffix, pin assignments, supply limits, clock accuracy, and supervisor thresholds for BQ4802LYDSH and the proposed alternative. In particular, BQ4802LYDWR, BQ4802YDWR, and BQ4802YPWR are suitable only for formal compatibility review because the verified dataset does not provide a complete suffix-level cross-reference.
Compliance Information
The supplied verified snippets do not contain explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statements. Compliance must be confirmed from the current manufacturer product page or material declarations.
