BQ4802LYDW - Parallel RTC with CPU Supervisor | Texas Instruments
MPN： BQ4802LYDW ✓ 啟用中BQ4802LYDW 概覽
A real-time clock, or RTC, is a low-power timing peripheral that retains calendar information and provides the host processor with a readable time and date. The BQ4802LYDW belongs to the clock and timing hierarchy as a parallel-interface RTC, combining timekeeping, century-based calendar management, processor supervision, and external nonvolatile SRAM backup control rather than requiring these functions as separate components.
The supplied product information identifies a parallel 28-pin SOIC package and a 3 V supply configuration. Its century-based calendar is suited to systems that must maintain date information across the 2000-year boundary. The integrated CPU supervisor supports dependable restart or reset behavior after power disruption, while external NVSRAM control is intended to preserve data held in an external SRAM through a controlled backup path. Exact time accuracy, current consumption, supervisor timing, and SRAM voltage thresholds were not included in the verified web data and must be taken directly from the manufacturer datasheet.
The device is designed for embedded systems requiring a dedicated wall-clock function. A host microcontroller or microprocessor can read and write time through the parallel bus, while the RTC maintains the time-of-day record. In designs using external SRAM, the NVSRAM-control function coordinates the retention path; exact capacitor values, logic levels, and supported memory arrangements require confirmation from the manufacturer documentation.
Typical applications include industrial control systems, point-of-sale terminals, fax machines, and copiers. In an industrial controller, the BQ4802LYDW can preserve timestamps and calendar data even when the main processor is reset or power is interrupted. In office equipment, its Y2K-compliant calendar behavior supports reliable date reporting across century transitions. The parallel interface is especially appropriate for systems that already use a bus architecture and do not require an I2C or SPI interface.
When designing a replacement, engineers should verify the exact package, pin mapping, electrical limits, supervisor behavior, and external NVSRAM connection before substitution. The verified distributor listing identifies BQ4802LYDW as a Texas Instruments parallel RTC clock/calendar in a 28-SOIC package. Confirm the official TI datasheet for pin names, absolute maximum ratings, recommended operating conditions, and application-specific circuit examples.
直接替換替代品，適用於 BQ4802LYDW — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： BQ4802LYDW （相同外形與佔位） — 差異在於 Device Type, Package, Supply Voltage.
BQ4802LYDWRG4
✅ 直接替換聯絡詢價
查看資料表 →BQ4802LYDW 規格
| Device Type | Parallel real-time clock and calendar IC |
| Timekeeping Features | Time-of-day clock |
| Calendar Features | Century-based calendar |
| Supervisor Function | CPU supervisor |
| External Memory Function | External NVSRAM control |
| 供應電壓 | 3 V |
| 介面類型 | Parallel |
| 封裝 | 28-pin SOIC |
| Package Width | 0.295 inch (7.50 mm) |
| Device Category | Real Time Clocks |
| Clock/Calendar Function | RTC clock/calendar |
| Y2K Compliance | Y2K-compliant |
| Typical Applications | Fax machines, copiers, industrial control systems, point-of-sale systems |
| 腳位數 | 28 pins |
| 安裝類型 | Surface mount |
BQ4802LYDW 0.295 inch (7.50 mm) 腳位配置指南
BQ4802LYDW（0.295 inch (7.50 mm) 封裝）的腳位配置。 腳位編號、功能與連接圖定義於製造商資料手冊中。請參閱該手冊以取得確切的封裝尺寸與焊接指引。
無詳細腳位定義資料： BQ4802LYDW.
請參閱 資料表 以查看完整腳位配置。
典型應用
BQ4802LYDW 適用於 6 應用s: Industrial Control Systems, Point-of-Sale Terminals, Fax Machines, Copiers and Office Equipment, External SRAM Data Retention, Embedded Data Loggers.
Industrial Control Systems
The BQ4802LYDW fits industrial controllers that need wall-clock timestamps, century-based calendar handling, and a CPU supervisor in one 3 V device. Its parallel interface can connect to a microprocessor or microcontroller that already uses a bus-oriented control architecture. The integrated supervisor provides a dedicated path for restarting the host after a processor failure, while the external NVSRAM-control function can help preserve data in an external SRAM during power transitions. Exact bus timing, reset timing, and retention-circuit values must be verified from the TI datasheet before layout.
推薦
Point-of-Sale Terminals
For point-of-sale equipment, the BQ4802LYDW provides a dedicated time-of-day source and century-based calendar for transaction records. The 3 V supply configuration fits systems designed around low-voltage digital logic, while the parallel interface allows the host processor to access the RTC without an external serial transceiver. The CPU-supervisor feature can improve recovery from a stalled controller, and external NVSRAM control can support retention of transaction-related data stored outside the processor. Validate timestamp accuracy, supervisor timing, and SRAM support against the manufacturer documentation.
推薦
Fax Machines
The BQ4802LYDW is identified by Texas Instruments as suitable for fax machines, where maintaining date and time information is important for document processing and system logging. Its parallel RTC/calendar provides a clear host-readable timekeeping function, while the century-based calendar addresses Y2K-related date handling. The CPU supervisor can support orderly recovery if the main controller stops responding. Because fax-machine power architectures vary, the exact NVSRAM backup connection and reset polarity must be verified against the TI application information and the host circuit.
推薦
Copiers and Office Equipment
Copiers and similar office equipment can use the BQ4802LYDW to maintain a system date across power cycles and record operational events accurately. The parallel interface is useful in legacy and industrial equipment architectures that already expose processor bus signals, while the integrated CPU supervisor adds a hardware recovery function. The external NVSRAM-control capability is relevant when job data or configuration information must survive a power interruption. The package and bus arrangement should be checked carefully because these products often use legacy connector and power-system conventions.
推薦
External SRAM Data Retention
The BQ4802LYDW is suited to embedded systems that use an external SRAM together with a dedicated backup path. Its external NVSRAM-control function can coordinate the switch between normal operation and retention during power transitions, while the RTC provides time and calendar context for stored records. This arrangement can extend the useful life of nonvolatile SRAM systems without placing all storage functions inside the RTC. Confirm the supported SRAM topology, voltage levels, backup capacitance, and switching thresholds in the manufacturer datasheet before releasing the circuit.
推薦
Embedded Data Loggers
An embedded data logger can use the BQ4802LYDW to retain accurate wall-clock time while the main processor is busy acquiring or processing data. The 3 V RTC/calendar is suitable for low-voltage embedded systems, and the parallel bus provides direct access from the logging controller. The century-based calendar helps avoid date rollover surprises in long-life deployments, while the CPU-supervisor function can flag or reset a failed logger. Because the supplied data does not state RTC accuracy or backup timing, those values should be checked against the TI datasheet and the logger's power-loss requirements.
推薦
推薦產品摘要
工程參考資料，適用於 BQ4802LYDW — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | BQ4802LYDWRG4 |
|---|---|---|
| Brand | Texas Instruments | Texas Instruments |
主要差異化特點
- Integrated CPU supervision (對比Generic basic RTC)
- External NVSRAM control (對比Generic RTC without memory-retention control)
- Century-based calendar (對比Calendar-limited RTC)
- Parallel integration (對比Serial-interface RTC)
設計說明
Design the 3 V supply, decoupling, and backup path directly from the TI datasheet. The verified web data confirms a 3 V configuration and external NVSRAM-control function, but it does not provide operating-voltage limits, current consumption, or backup capacitor values. Confirm those values before selecting passive components and verify that the external SRAM remains within its permitted voltage range during normal operation and retention.
Place the RTC and its required support components close to the host bus and power-entry circuitry. Keep the 28-pin SOIC footprint, pin numbering, ground connections, and external NVSRAM routing aligned with the official TI package drawing. Because the supplied data does not reproduce the pinout, do not finalize the PCB until every pin name and connection has been checked against the manufacturer datasheet.
Do not substitute a generic RTC solely because it also tracks time. BQ4802LYDW also integrates a century-based calendar, CPU supervisor, and external NVSRAM control; replacing it with a device lacking one of those functions can change system behavior. Also verify SOIC orientation, supply polarity, bus levels, reset polarity, and power-loss behavior before releasing a replacement design.
Separate sensitive timing and backup-control routing from noisy switching nodes and high-current loads. Keep the RTC reference and power connections short where the datasheet recommends them, and provide a low-impedance ground return. The retrieved data does not specify decoupling values or layout dimensions, so use the manufacturer's recommended application circuit rather than relying on generic values.
合規資訊
The supplied verified web data does not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. Verify these claims using the manufacturer product documentation or current supplier compliance records.