BQ4847YMT RTC Module with CPU Supervisor | Texas Instruments
MPN： BQ4847YMT ✓ 啟用中BQ4847YMT 概覽
A real-time clock, or RTC, is a clock-and-timing IC that maintains time independently of the system processor. It typically supplies calendar and alarm information, supports battery-backed operation during main-power loss, and allows embedded equipment to retain accurate timestamps after restart. The BQ4847YMT combines the RTC, clock source, backup battery, supervisor circuitry, and external-SRAM retention control in one module, reducing the number of separate timing and power components a board must accommodate.
Key features include BCD time-of-day and calendar counting from seconds through years, an integrated battery and crystal, an on-chip battery-backup switchover circuit, nonvolatile control for an external SRAM, a 130 mAh battery capacity, and ±1 minute per month clock accuracy. The CPU-supervisor function helps system firmware distinguish normal operation from reset or power-failure events, while watchdog, interrupt, reset, and battery-low warning functions support reliable embedded-control behavior.
The module uses a parallel interface rather than the serial bus found in many compact RTC packages. According to the verified distributor descriptions, it is packaged as a 28-DIP module and is categorized as a clock/calendar RTC IC. The integrated battery and crystal mean the associated crystal and primary backup-cell implementation details are contained within the module rather than requiring the same external arrangement as a conventional RTC IC.
Typical uses include industrial controllers, data-acquisition equipment, embedded instruments, access-control systems, and legacy computer hardware requiring a parallel RTC interface. Designers should preserve the module's pinout and battery behavior, account for main-supply and backup-supply sequencing, and verify reset, watchdog, and SRAM-retention requirements against the application. The supplied verified data does not specify a full electrical limit table, operating-temperature range, or lead-time figures, so those details should be confirmed in the manufacturer documentation.
直接替換替代品，適用於 BQ4847YMT — 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： BQ4847YMT （相同外形與佔位） — 差異在於 Interface, Mounting Type, Package, REACH Status, RoHS Status.
BQ4847-MT
✅ 直接替換📋 參考替代品（不在目錄中）
BQ4845
✅ 直接替換📋 參考替代品（不在目錄中）
BQ4847YMT 規格
| Product Type | Real-time clock module with CPU supervisor |
| Time Representation | BCD seconds through years |
| 介面 | Parallel clock/calendar interface |
| Integrated Functions | RTC, CPU supervisor, watchdog timer, reset, interrupts, battery-low warning |
| Battery Type | Integrated 130 mAh battery |
| Clock Accuracy | ±1 minute per month |
| Backup Control | On-chip battery-backup switchover circuit |
| External SRAM Control | Nonvolatile control for an external SRAM |
| Crystal | Integrated quartz crystal |
| 封裝 | 28-DIP module |
| Package Width | 15.49 mm |
| Distributor Listing Size | 0.61 inch |
| 安裝類型 | Through-hole DIP module |
| Reset and Watchdog | CPU supervisor with watchdog and reset functions |
| Battery Warning | Battery-low warning feature |
| Interrupt Support | Interrupt features |
| Calendar Range | Seconds through years |
| RoHS 狀態 | unknown |
| REACH Status | unknown |
| AEC-Q100 Qualification | unknown |
| Lead-Free Status | unknown |
BQ4847YMT 15.49 mm 腳位配置指南
BQ4847YMT（15.49 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： BQ4847YMT.
請參閱 資料表 以查看完整腳位配置。
典型應用
BQ4847YMT 適用於 6 應用s: Industrial Data Loggers, Embedded Access-Control Systems, Data-Acquisition Instruments, Legacy Computer Peripherals, Battery-Backed Embedded Control, Test and Measurement Equipment.
Industrial Data Loggers
The BQ4847YMT fits industrial data-logging equipment that must retain timestamps when the main supply fails or the controller restarts. Its ±1 minute per month clock accuracy provides a defined timing basis, while the integrated 130 mAh battery supports backup operation without adding a separate crystal and primary backup cell. The parallel clock/calendar interface can be connected to a controller with suitable GPIO or bus-interface logic. The CPU-supervisor, reset, watchdog, interrupt, and battery-low warning functions help the firmware distinguish power events and protect the logging sequence. Before layout, confirm voltage levels, reset timing, and SRAM-control requirements in the manufacturer datasheet.
推薦
Embedded Access-Control Systems
BQ4847YMT is appropriate for access-control and security equipment requiring a persistent calendar record independent of the main processor. The RTC counts seconds through years in BCD format, which supports event timestamps across long operating periods. The integrated battery and quartz crystal simplify the backup-timekeeping implementation, while the CPU supervisor and reset features provide useful system-state inputs for lockout and event-log handling. The external-SRAM retention control can support designs that need nonvolatile storage behavior, although the exact SRAM interface must be verified. Use the parallel interface and the module’s through-hole package in a layout that accounts for mechanical clearance and battery access.
推薦
Data-Acquisition Instruments
The BQ4847YMT can serve as the time base in measurement instruments where samples must be correlated with a calendar and retained across power interruptions. Its ±1 minute per month specification provides a useful accuracy reference for slow-changing process and laboratory records, and the backup battery helps preserve elapsed time during service or restart. The integrated crystal removes the need for a separate oscillator in the timer subsystem, leaving the design team to focus on bus decoding and signal-chain calibration. Watchdog and reset functions can reduce recovery time after unexpected events, while battery-low warning permits maintenance before timekeeping becomes unreliable. Verify operating temperature and supply limits against the exact manufacturer documentation.
推薦
Legacy Computer Peripherals
BQ4847YMT is suited to legacy computer and peripheral designs that require a parallel RTC/calendar interface rather than a modern serial RTC. The module combines timekeeping, crystal, backup battery, and CPU-supervisor functions in a 28-DIP package, which can simplify retrofitting compared with reconstructing all functions from discrete components. The external-SRAM backup-control feature is useful where retained data or configuration state must survive a main-power transition. Designers should verify signal timing, address or data-line mapping, and supply sequencing because the supplied data does not include a complete pinout or electrical table. Mechanical design must also account for the module’s 15.49 mm width and through-hole construction.
推薦
Battery-Backed Embedded Control
The BQ4847YMT fits embedded controllers that must know the date and time after a brownout, watchdog reset, or power cycle. Its integrated 130 mAh battery and on-chip backup switchover provide a defined backup-power concept, while the CPU supervisor and reset functions can inform the application firmware about the source of recovery. The integrated crystal makes the module a compact timing subsystem for control boards that do not need a separately calibrated clock source. Battery-low warning is useful for preventive maintenance, and the interrupt capability can flag RTC-related events. Confirm whether the external-SRAM control feature is needed and validate all backup-supply timing in the exact datasheet.
推薦
Test and Measurement Equipment
BQ4847YMT can provide timestamp continuity for test and measurement systems whose records need to remain meaningful after a mains interruption. The ±1 minute per month clock accuracy is suitable for event-level and general-purpose instrument timestamping, while the 130 mAh integrated battery supports the module’s backup function. The CPU-supervisor, watchdog, reset, and interrupt features allow a controller to distinguish deliberate shutdowns from faults and schedule recovery actions. The parallel interface may require level-compatible logic and careful signal routing, so the design should verify voltage thresholds and timing. The 28-DIP module also provides a mechanically identifiable through-hole footprint for legacy and industrial instrument platforms.
推薦
推薦產品摘要
工程參考資料，適用於 BQ4847YMT — 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 | BQ4847-MT | BQ4845 |
|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
| RTC Function | Real-time clock with clock/calendar | Real-time clock module | Functionally equivalent RTC family part per verified material |
主要差異化特點
- Integrated backup timing subsystem (對比BQ4845)
- External-SRAM retention control (對比BQ4802LY)
- Parallel clock/calendar integration (對比M41T82RM6F)
設計說明
Validate main-supply, backup-supply, and external-SRAM power sequencing against the manufacturer datasheet before connecting the module. The verified feature set confirms an on-chip battery-backup switchover circuit and nonvolatile external-SRAM control, but the supplied data does not provide the required voltage thresholds or timing windows. Keep main-rail decoupling close to the board power entry and ensure that backup operation cannot backfeed or damage the SRAM or system supply.
Treat BQ4847YMT as a 28-DIP through-hole module rather than a generic 28-pin IC footprint. Confirm the mechanical drawing, pin numbering, battery clearance, and connector orientation before layout. The distributor listing identifies a 15.49 mm-wide module, so provide the specified keepout and avoid placing tall or heat-generating components that could interfere with the module body, battery area, or nearby signal routing.
Do not substitute BQ4802LY or an assumed BQ4845 variant without a complete pin-level comparison. The verified material specifically notes that BQ4802LY lacks an integrated crystal and may require an adapter board, while it does not establish BQ4845 as a direct BQ4847YMT drop-in replacement. Verify pinout, supply levels, reset behavior, battery backup, calendar access, and external-SRAM control before releasing a replacement design.
Route the parallel clock/calendar interface away from noisy switching nodes and provide a defined ground reference close to the controller interface. The supplied data confirms a parallel interface but does not specify signal timing or logic levels, so use the manufacturer timing diagram and external buffering or level translation only where the datasheet requires it. Keep the module’s crystal and backup circuitry away from high-current edges and maintain a stable return path.
合規資訊
The supplied verified web data does not provide compliance declarations for BQ4847YMT. RoHS, REACH, AEC-Q100, lead-free, halogen-free, and conflict-minerals status remain unknown until confirmed through the current manufacturer or authorized-distributor documentation.
