BQ4285LS - 114x8 NVRAM RTC, 3V | Texas Instruments
Référence : BQ4285LS ✓ Actif| Qté | Prix unitaire | Total |
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| 1 | $0 | $0,00 |
| 10 | $0 | $0,00 |
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| 500 | $0 | $0,00 |
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BQ4285LS Présentation
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.
Alternatives de remplacement direct pour BQ4285LS — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
Aucune alternative de remplacement direct disponible pour ce produit.
Demander des alternativesBQ4285LS Spécifications
| Product Type | Real-Time Clock (RTC) IC with NVRAM control |
| Device Function | Clock/calendar with 114x8 NVRAM |
| Tension d'alimentation | 3 V |
| General-Purpose NVRAM | 114 bytes |
| NVRAM Organization | 114 x 8 bits |
| Interface Width | 24 bits |
| Type d'interface | Parallel |
| Boîtier | 24-SOIC |
| Package Width | 0.295 inch (7.50 mm) |
| Type de montage | 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 |
Guide de configuration des broches du BQ4285LS 0.295 inch (7.50 mm)
Configuration des broches du BQ4285LS (boîtier 0.295 inch (7.50 mm)). La numérotation des broches, les fonctions et les schémas de connexion sont définis dans la fiche technique du fabricant. Consultez-la pour l'empreinte exacte et les directives de soudage.
Aucune donnée de brochage détaillée disponible pour BQ4285LS.
Consultez la fiche technique pour la configuration complète des broches.
Applications typiques
BQ4285LS convient pour 6 applications: 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.
Recommandé
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.
Recommandé
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.
Recommandé
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.
Recommandé
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.
Recommandé
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.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour BQ4285LS — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit |
|---|---|
| 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 |
Principaux différenciateurs
- 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)
Notes de conception
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.
Informations de conformité
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.
