BQ4845S-A4NTRG4 - 5V Parallel RTC with Supervisor | TI
MPN: BQ4845S-A4NTRG4 ✓ نشطBQ4845S-A4NTRG4 نظرة عامة
A real-time clock, or RTC, is a timing peripheral that retains seconds, minutes, hours, date, and calendar information independently of the main processor clock. The BQ4845 belongs to the clock and timing IC hierarchy, where it combines an RTC with voltage supervision, watchdog, reset, interrupt, and nonvolatile-memory control functions. This integration reduces the number of separate system-support components required around a microprocessor.
The BQ4845S-A4NTRG4 uses a BCD clock and calendar format and supports a parallel host interface. Its integrated 32.768 kHz crystal connections support accurate timekeeping, while the backup-cell path maintains the clock during main-power loss. The CEOUT output can write-protect external nonvolatile SRAM, and the VOUT output provides a battery-voltage signal for system monitoring.
The CPU-supervisor section adds power-fail detection, processor reset, watchdog timing, and interrupt support. According to the manufacturer datasheet, an internal approximately 100 kilohm-equivalent resistor network biases the watchdog input, while internal comparators detect the resulting level and disable the watchdog. Below the power-fail threshold, watchdog operation is disabled and the watchdog input is disconnected from the internal network.
Typical uses include industrial control systems, point-of-sale terminals, fax machines, copiers, data loggers, computers, and embedded equipment requiring calendar retention. Its 28-pin SOIC format also supports designs that need parallel access to time registers, alarm functions, supervisor status, and backup-battery information.
PCB design should place the crystal and associated load components close to the oscillator pins and keep backup-supply routing away from high-current switching nodes. Because the main supply and backup cell have separate operating ranges, designers should verify both rails under worst-case battery depletion, startup, and power-transition conditions.
This product summary consolidates the verified manufacturer and distributor information into a design-focused reference covering the BQ4845S-A4NTRG4 clock, watchdog, backup-battery, and SRAM-control functions. It also identifies same-family candidates, highlights unresolved comparison parameters, and supplies practical selection guidance beyond a basic distributor listing.
بدائل مباشرة لـ BQ4845S-A4NTRG4 — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع BQ4845S-A4NTRG4 (نفس عامل الشكل والبصمة) — يختلف في Package, Product Type, Interface, Timekeeping Format.
BQ4845S-A4NTR
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←BQ4845YS-A4NTR
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←BQ4845YS-A4NG4
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
BQ4845YS-A4NTRG4
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
BQ4845S-A4G4
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←BQ4845S-A4NTRG4 المواصفات
| Product Type | Parallel real-time clock and calendar with CPU supervisor |
| Main Supply Voltage Range | 4.75 V to 5.5 V |
| Backup Battery Voltage Range | 2.3 V to 4 V |
| Crystal Frequency | 32.768 kHz |
| Clock Format | BCD |
| Date Format | BCD |
| Host Interface | Parallel |
| العلبة | 28-pin SOIC, 7.50 mm width |
| نوع التركيب | Surface mount |
| Operating Features | Alarm, daylight-saving time, leap year, watchdog timer, processor reset, interrupt, and battery-low warning |
| Calendar Range | 100 years |
| Backup Clock Operating Current | Less than 500 nA |
| Watchdog Input Bias | Approximately 1.6 V through a 100 kilohm-equivalent internal resistor network |
| Battery Voltage Output | VOUT output available |
| External SRAM Control | CEOUT write-protection output available |
| Power-Fail Behavior | Watchdog disabled and WDI disconnected from the internal resistor network below the power-fail threshold |
دليل تكوين أطراف BQ4845S-A4NTRG4 28-pin soic, 7.50 mm width
تكوين الأطراف لـ BQ4845S-A4NTRG4 (حزمة 28-pin soic, 7.50 mm width). يتم تعريف ترقيم الأطراف والوظائف ومخططات التوصيل في ورقة البيانات الفنية من الشركة المصنعة. راجعها للحصول على البصمة الدقيقة وإرشادات اللحام.
لا تتوفر بيانات مفصلة لمخطط التوصيلات لـ BQ4845S-A4NTRG4.
راجع ورقة البيانات للحصول على تكوين الأطراف الكامل.
التطبيقات النموذجية
BQ4845S-A4NTRG4 مناسب لـ 6 التطبيقs: Industrial Control Systems, Point-of-Sale Terminals, Data Loggers, Fax Machines and Copiers, Backup-Powered Embedded Equipment, Computer and Peripheral Timing.
Industrial Control Systems
The BQ4845S-A4NTRG4 suits industrial controllers that must preserve event timestamps and calendar records during power interruptions. Its 4.75 V to 5.5 V main supply, 3 V backup-battery connection, 32.768 kHz crystal interface, and less-than-500 nA backup operating current support continuous timekeeping when VCC is removed. The parallel bus provides direct access to time, calendar, alarm, and supervisor registers, while the integrated watchdog and processor-reset functions can supervise an embedded controller without separate supervisor ICs. For an industrial design, confirm the exact operating-temperature grade and verify the watchdog thresholds against the manufacturer datasheet before release.
موصى به
Point-of-Sale Terminals
Point-of-sale terminals benefit from a dedicated calendar clock that remains valid when the main system loses power. The BQ4845S-A4NTRG4 maintains BCD time and date through a 3 V backup cell, covers a 100-year calendar, and includes alarm and daylight-saving functions that can support scheduled transactions and record handling. Its parallel interface is useful with processors that already provide a bus-oriented control architecture. The CEOUT output can also control write protection for external SRAM, although the designer must confirm that the terminal's memory topology and retention requirements match the intended implementation.
موصى به
Data Loggers
A data logger often needs accurate timestamps even after an unexpected power loss, making the BQ4845S-A4NTRG4's backup-powered RTC a practical timing component. The device combines a 32.768 kHz crystal oscillator with a 3 V backup battery, a 100-year calendar, alarm handling, and a low-power backup current below 500 nA. A host processor can read the parallel clock registers when the logger starts and correlate stored measurements with the retained time. Designers should allow adequate layout separation between the oscillator and backup-supply routing, and should validate clock accuracy across the intended temperature range because that limit was not included in the supplied verified snippets.
موصى به
Fax Machines and Copiers
The BQ4845S-A4NTRG4 addresses the timekeeping and power-management needs identified by Texas Instruments for fax machines and copiers. It maintains date and time during main-power loss, supports alarms, and integrates watchdog and processor-reset functions for embedded print-system controllers. The 5 V main-supply range fits the documented operating environment, while the parallel interface can support deterministic access by the equipment controller. CEOUT can provide conditional write protection for external nonvolatile SRAM, helping preserve documents or settings when the primary rail collapses. Exact timer behavior and board-level integration should be checked against the complete manufacturer schematic and pin descriptions.
موصى به
Backup-Powered Embedded Equipment
Equipment that must resume operations with valid timestamps after a power interruption can use the BQ4845S-A4NTRG4 as a dedicated backup time source. The RTC supports a 2.3 V to 4 V battery range, including the documented 3 V cell, and its backup operating current is less than 500 nA. The processor-reset, watchdog, battery-low, and interrupt functions provide useful fault-management signals around the host processor. Because the device is a parallel-interface part in a 28-pin SOIC package, it is best suited to boards that already have sufficient bus and routing resources and can preserve the reference clock layout without modification.
موصى به
Computer and Peripheral Timing
The BQ4845S-A4NTRG4 can support legacy or industrial computer peripherals that require a dedicated parallel real-time clock. The part tracks seconds through years in BCD format, supplies a 100-year calendar, and keeps operating from a backup battery when the system supply is removed. Its alarm and watchdog capabilities allow a host processor to be scheduled or supervised independently of the main real-time operating system. Integration is most practical on custom 28-pin SOIC boards with a parallel bus, rather than on a conventional plug-in PC interface without additional glue logic. Pin-level review remains essential because the verified source did not provide a complete numbered pin table.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ BQ4845S-A4NTRG4 — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | BQ4845S-A4NTR | BQ4845YS-A4NTR | BQ4845YS-A4NG4 | BQ4845YS-A4NTRG4 | BQ4845S-A4G4 |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | SOIC-28 | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same |
أبرز الفروقات
- Combines timekeeping and CPU supervision (مقابلBQ4285S-SB2TR)
- Maintains time through main-power loss (مقابلBQ4845S-A4G4)
- Supports external SRAM retention control (مقابلBQ4845YS-A4NTR)
- Direct 32.768 kHz crystal interface (مقابلBQ4845YS-A4NG4)
ملاحظات التصميم
Route the 32.768 kHz crystal and its load network with short, symmetric connections to the oscillator pins, and keep the region free from switching-power traces and high-current motor or relay wiring. Place the backup-cell connection so that main-rail transients cannot couple directly into it. The supplied data confirms direct 32.768 kHz crystal and 3 V battery connections but does not provide the manufacturer layout figures, so exact guard-ring and capacitor placement should follow the TI datasheet.
Validate startup and power-loss behavior with both the main 4.75 V to 5.5 V supply and the 2.3 V to 4 V backup range. The RTC is intended to operate from a 3 V cell and continue maintaining time when VCC disappears. Check battery-low timing, the VOUT battery-voltage signal, and the power-fail threshold against the system requirements. Do not allow the backup rail to exceed its specified range during abnormal charging or transient conditions.
Do not treat every 28-pin SOIC RTC as a pin-compatible substitute. The verified candidates belong to the TI BQ4845 family, but the supplied results explicitly note that some electrical characteristics can differ. Before replacing the BQ4845S-A4NTRG4, compare the complete ordering table, pin functions, watchdog thresholds, alarm behavior, electrical limits, temperature grade, and qualification status. A matching package alone does not prove drop-in compatibility.
Account for the parallel interface when designing bus timing and firmware. The RTC supplies direct clock, calendar, alarm, supervisor, interrupt, and backup-related signals, but the verified snippets do not include complete access-time or timing-edge parameters. Confirm read and write cycle requirements, chip-select behavior, and interrupt polarity in the manufacturer datasheet. Software should also handle rollover, alarm-mask, and power-transition states rather than assuming an always-valid main supply.
معلومات الامتثال
The supplied verified snippets do not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status for this ordering code. AEC-Q100 is marked not_applicable because the device was not identified as an automotive-qualified part in the provided data; this is not an automotive-grade approval.
