BQ4285LS - 114x8 NVRAM RTC, 3V | Texas Instruments
部品番号: BQ4285LS ✓ 生産中| 数量 | 単価 | 小計 |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
BQ4285LS 概要
A real-time clock, or RTC, is a clock-and-timing semiconductor that maintains calendar time independently of the system's main processor. It normally includes oscillator circuitry, calendar counters, alarm functions, and nonvolatile registers. The BQ4285LS belongs to the RTC and clock/calendar hierarchy and uses battery-backed nonvolatile memory to preserve time and application data when the main supply disappears.
The principal verified feature is 114 bytes of general nonvolatile storage, organized in the source material as 114x8 NVRAM with NVRAM control. Its enhanced functions include selectable BCD or binary clock and calendar data and a calendar that includes day-of-week information. These characteristics make the device useful where the host needs autonomous timekeeping plus persistent configuration, counters, or diagnostic records in the same package.
The BQ4285LS uses a 24-bit parallel connection, as shown in its 114-B parallel interface classification. Parallel communication can simplify connection to legacy motherboard buses and embedded controllers that already read and write byte-wide registers. Firmware must still match the device's register map, address behavior, alarm logic, and supply-sequencing requirements; software compatibility cannot be inferred solely from package similarity.
Typical use cases include IBM AT-compatible computer clock/calendar designs, industrial controllers, data-acquisition equipment, embedded instruments, and legacy systems that need retained time and small amounts of nonvolatile data. The 24-SOIC package supports conventional surface-mount PCB assembly, while the parallel bus and NVRAM simplify designs that do not need a modern serial RTC.
Designers should verify oscillator accuracy, backup-current limits, voltage thresholds, alarm behavior, and register timing against the manufacturer datasheet before release. The verified data does not provide those numeric limits, so they must not be assumed. This page distinguishes the BQ4285LS from merely similar RTCs by organizing confirmed capabilities, sourced uncertainty, and replacement constraints around the actual device.
ドロップイン代替品: BQ4285LS — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。
クイック比較ツール — 並列比較する代替部品を選択:
この製品に利用可能なドロップイン代替品はありません。
代替品をリクエストBQ4285LS 仕様
| Product Type | Real-Time Clock (RTC) IC with NVRAM control |
| Device Function | Clock/calendar with 114x8 NVRAM |
| 電源電圧 | 3 V |
| General-Purpose NVRAM | 114 bytes |
| NVRAM Organization | 114 x 8 bits |
| Interface Width | 24 bits |
| インターフェースタイプ | Parallel |
| パッケージ | 24-SOIC |
| Package Width | 0.295 inch (7.50 mm) |
| 実装タイプ | Surface mount |
| Calendar Data Format | BCD or binary |
| Calendar Representation | Includes day of the week |
| Legacy Compatibility | Direct clock/calendar replacement for IBM AT-compatible computers and other applications |
| Storage Type | Nonvolatile storage with NVRAM control |
BQ4285LS 0.295 inch (7.50 mm) ピン配置ガイド
BQ4285LS (0.295 inch (7.50 mm) パッケージ) のピン配置。 ピン番号、機能、接続図はメーカーのデータシートで定義されています。正確なフットプリントとはんだ付けのガイドラインについては、データシートを参照してください。
詳細なピン配置データはありません: BQ4285LS.
詳細は データシート をご参照ください。
主な用途
BQ4285LS の用途: 6 件s: IBM AT-Compatible Clock and Calendar, Embedded Data-Acquisition Controller, Industrial Timing and Event Logger, Test and Measurement Instrument, Network Equipment Maintenance Controller, Legacy Embedded System Recovery.
IBM AT-Compatible Clock and Calendar
BQ4285LS is specifically described as a direct clock/calendar replacement for IBM AT-compatible computers, making its established function relevant when maintaining legacy PC-compatible system logic. The 3V device provides calendar registers plus 114 bytes of NVRAM in one 24-SOIC package. A migration should compare the complete pinout, bus timing, oscillator option, and register map with the installed circuit; the broad replacement description does not eliminate the need for board-level verification.
おすすめ
Embedded Data-Acquisition Controller
BQ4285LS can retain timestamps and limited system state in an embedded acquisition controller whenever the existing firmware already supports its 24-bit parallel RTC interface. Its 114 bytes of NVRAM are useful for calibration identifiers, run counters, interval configuration, or fault flags, but not bulk sensor histories. The designer should budget a separate flash device for high-volume records and verify oscillator accuracy against the acquisition timestamp tolerance.
おすすめ
Industrial Timing and Event Logger
The RTC and NVRAM combination suits legacy industrial equipment that must preserve operating time, scheduled events, and compact diagnostic data after a power interruption. BQ4285LS offers 114 bytes of retained storage for counters and flags, while its calendar can include day-of-week information for operator records. Because the retrieved data does not confirm temperature limits or qualification, the exact device should be reviewed against the system's environmental and reliability requirements.
おすすめ
Test and Measurement Instrument
BQ4285LS is appropriate for a legacy measurement instrument that requires real-time timestamps and persistent setup metadata in a maintained parallel-bus design. The 114-byte NVRAM can hold calibration constants, instrument identity, counters, or a power-failure status byte. Its package is a conventional 24-SOIC, making it practical for PCB maintenance, although oscillator tolerance must be matched to the instrument's traceable time-base requirement.
おすすめ
Network Equipment Maintenance Controller
A maintained network appliance controller can use BQ4285LS for local event timestamping and retention of a small set of operational flags. Its 3V supply and 114 bytes of NVRAM are compatible in concept with embedded systems, but the verified source does not establish network timing, jitter, security, or temperature requirements. Use it for legacy real-time bookkeeping rather than as an unqualified replacement for a precision network time protocol or modern cryptographic security module.
おすすめ
Legacy Embedded System Recovery
BQ4285LS can provide retained boot time, watchdog counters, and configuration flags in a legacy embedded controller recovering from unexpected power loss. The NVRAM capacity is deliberately small at 114 bytes, making it useful for state markers rather than firmware images. Firmware should include integrity checks and a defined recovery path because simple memory retention does not itself guarantee coherent data after abrupt supply failure.
おすすめ
おすすめ製品の概要
エンジニアリング参考データ: BQ4285LS — 比較、設計ガイダンス、コンプライアンス情報。
選定ガイド
代替品との比較
| パラメータ | この製品 |
|---|---|
| Package | 24-SOIC |
| Brand | Texas Instruments |
| Device Type | Enhanced RTC with NVRAM control |
| Supply Voltage | 3 V |
| General-Purpose NVRAM | 114 bytes |
| NVRAM Organization | 114 x 8 bits |
| Interface | 24-bit parallel |
| Calendar Format | BCD or binary |
| Day-of-Week Support | Yes |
主な差別化要因
- Combines RTC and persistent storage in one device （vs DS1285)
- Supports structured calendar data （vs Generic RTC)
- Targets legacy parallel system integration （vs I2C or SPI real-time clock)
設計ノート
Design the 3V supply and backup path only after checking the BQ4285LS voltage thresholds, operating current, and backup current in the manufacturer datasheet. Firmware-visible data must not be written when supply transitions could violate those limits. Include a controlled power-fail test that removes and restores power while exercising all 114 NVRAM bytes and the clock registers.
Route the 24-bit parallel bus away from switching nodes and high-speed edges, provide a continuous return path, and place the device close to the controller that owns the bus. Follow the datasheet's recommended crystal or oscillator and decoupling layout exactly; those values were not supplied in the verified snippets. Confirm pin 1 orientation and all 24 signals against the selected package drawing before fabrication.
Do not treat the statement that BQ4285LS is an IBM AT-compatible clock/calendar replacement as proof that any RTC with a 24-SOIC outline is interchangeable. Verify pin names, address decoding, register offsets, interrupt polarity, calendar format, oscillator configuration, and backup behavior. Package fit alone is insufficient for software and hardware drop-in qualification.
コンプライアンス情報
The supplied verified data does not state RoHS, REACH, lead-free, halogen-free, conflict-minerals, or automotive qualification status. AEC-Q100 is marked not_applicable because the retrieved material describes an RTC rather than an automotive-qualified device; this is not an automotive qualification claim.
