BQ4802LYDWG4 - Parallel RTC with CPU Supervisor | Texas Instruments
Référence : BQ4802LYDWG4 ✓ ActifBQ4802LYDWG4 Présentation
A real-time clock is a clock-and-timing IC that maintains calendar time independently of the main processor. Within the product hierarchy, an RTC belongs to clock and timing devices, alongside oscillators, timers, and watchdogs. The BQ4802LY combines time-of-day tracking with a CPU supervisor, allowing a controller to determine whether the processor has reset and whether the system should enter a controlled recovery sequence.
The device uses a parallel host interface rather than a serial I2C or SPI interface. BCD clock data supports conventional year, month, day, hour, minute, and second organization, while the century-based calendar addresses the Y2K-compliant positioning of this RTC family. Its integrated CPU supervisor reduces the number of separate reset-monitor components required in a processor-based design.
External NVSRAM control is another distinguishing function. When paired with compatible nonvolatile SRAM, this control path can support retention and integrity coordination for stored data. The available package configuration is 28-pin SOIC, which is suitable for conventional surface-mount PCB assembly and industrial control systems operating across the stated 0°C to 70°C range.
Typical uses include industrial controllers, point-of-sale equipment, copiers, fax machines, embedded processors, and other systems requiring calendar time plus reset supervision. Because the interface is parallel, the host must provide address and data lines and must accommodate the device's bus timing in software or hardware. Firmware should also handle rollover and validity logic rather than assuming that every read contains a valid calendar value.
Designers should preserve the manufacturer's recommended bypass and interface layout, validate all read and write timing in the target system, and confirm backup-battery behavior before deployment. The parallel bus simplifies host connectivity but requires more PCB routing and pins than a serial RTC. Availability, lifecycle, exact accuracy, and current commercial pricing were not stated in the supplied records and should be confirmed with the manufacturer or an authorized distributor.
This page combines the verified product description, package and operating information, source links, practical implementation guidance, and clearly identified data gaps. It also distinguishes documented device characteristics from assumptions, helping engineers make sourcing and design decisions without treating unverified electrical details as guaranteed specifications.
Alternatives de remplacement direct pour BQ4802LYDWG4 — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec BQ4802LYDWG4 (même facteur de forme et même empreinte) — différant par Package Width, Device Type, Supply Voltage.
BQ4802LYDWR
✅ Remplacement directContactez-nous pour le prix
Voir la fiche technique →BQ4802YDWR
✅ Remplacement directContactez-nous pour le prix
Voir la fiche technique →BQ4802LYDWG4 Spécifications
| Device Type | Parallel real-time clock IC with CPU supervisor and external NVSRAM control |
| RTC Function | Y2K-compliant time-of-day clock with century-based calendar |
| Tension d'alimentation | 3 V Vcc |
| Host Interface | Parallel |
| Clock Data Format | BCD |
| CPU Supervisor | Integrated |
| External NVSRAM Control | Supported |
| Boîtier | 28-pin SOIC |
| Package Width | 7.50 mm |
| Type de montage | Surface mount |
| Température de fonctionnement | 0°C to 70°C |
| Calendar Century Support | Century-based calendar |
| Y2K Compliance | Y2K-compliant |
Guide de configuration des broches du BQ4802LYDWG4 7.50 mm
Configuration des broches du BQ4802LYDWG4 (boîtier 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 BQ4802LYDWG4.
Consultez la fiche technique pour la configuration complète des broches.
Applications typiques
BQ4802LYDWG4 convient pour 6 applications: Industrial Control Systems, Point-of-Sale Equipment, Copiers and Fax Machines, Embedded Data Loggers, Processor-Based Power Systems, Networked Embedded Equipment.
Industrial Control Systems
The BQ4802LYDWG4 fits industrial controllers that need time-stamped operating events, a century-based calendar, and supervisory reset detection. Its documented 3 V supply and 0°C to 70°C operating range align with controlled indoor factory equipment, while the parallel interface provides direct access to BCD clock and calendar data. The CPU supervisor can inform the controller logic that a reset occurred, helping the application execute a controlled initialization sequence. External NVSRAM control is also useful when the system must coordinate a processor with a nonvolatile memory device. Designers should validate electrical timing, backup behavior, and thermal limits against the final enclosure before production release.
Recommandé
Point-of-Sale Equipment
Cash registers and point-of-sale terminals benefit from a dedicated parallel RTC that preserves calendar time independently of the main processor. The BQ4802LYDWG4 provides Y2K-compliant time, a century-based calendar, and BCD-formatted clock data, supporting transaction logging and scheduled operations. Its CPU supervisor can help the terminal distinguish a normal software restart from a system fault, while the 3 V operating supply matches common embedded power architectures. The 28-pin SOIC package is practical for a surface-mount controller board, although the parallel bus requires more routing than an I2C or SPI clock.
Recommandé
Copiers and Fax Machines
The BQ4802LYDWG4 is appropriate for copiers and fax machines that need date, time, and document-management functions alongside processor reset supervision. A century-based Y2K-compliant calendar helps label stored jobs and scheduled transmissions, while the parallel interface allows the embedded processor to read clock data efficiently. The integrated CPU supervisor supports reliable behavior after power interruption or firmware restart. External NVSRAM control may support systems that retain operational records outside the main processor. Because operating behavior across the specified 0°C to 70°C range can affect timekeeping and reset thresholds, the final design should be validated in the target office-equipment environment.
Recommandé
Embedded Data Loggers
Embedded data loggers can use the BQ4802LYDWG4 to timestamp measurements with calendar information maintained independently of the acquisition processor. Its BCD time format and century-based calendar support structured daily records, while the CPU supervisor provides the host with evidence that a reset occurred after power loss or fault recovery. The 3 V supply and 28-pin SOIC package are compatible with compact surface-mount electronics designs. External NVSRAM control may also assist designs that coordinate the logger with nonvolatile storage. Firmware should validate calendar-read status, define rollover behavior, and reconcile RTC time with the host clock before relying on timestamps for compliance or diagnostics.
Recommandé
Processor-Based Power Systems
The BQ4802LYDWG4 can support processor-based power and industrial monitoring equipment that requires event chronology and supervisory reset control. Its integrated CPU supervisor helps firmware identify unexpected processor resets, while the Y2K-compliant century calendar supports audit logs and scheduled maintenance records. The device operates from 3 V and is available in a 28-pin SOIC package, allowing implementation alongside low-voltage embedded controllers. External NVSRAM control may be useful in systems where critical state must be coordinated with nonvolatile memory. Designers should pay particular attention to power-supply startup behavior, backup-battery requirements, and the possibility that the host and RTC lose valid time simultaneously after a complete power interruption.
Recommandé
Networked Embedded Equipment
The BQ4802LYDWG4 suits embedded network appliances that need local calendar time even when an external time service is unavailable. Its century-based Y2K-compliant calendar and CPU supervisor support reliable boot-state decisions, event logging, and authentication systems that depend on a maintained timestamp. The 3 V device can be placed close to the embedded processor in a 28-pin SOIC footprint, although the parallel interface adds signal routing compared with a serial RTC. External NVSRAM control can coordinate retained configuration or log data with the processor. Before deployment, engineers should verify oscillator accuracy under the specified 0°C to 70°C range and define a secure method for correcting time after network synchronization.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour BQ4802LYDWG4 — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | BQ4802LYDWR | BQ4802YDWR |
|---|---|---|---|
| Package | 28-SOIC | 28-SOIC | 28-SOIC |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
| Device Type | Parallel RTC with CPU supervisor and external NVSRAM control | Same-family parallel RTC; detailed suffix differences not stated | Closely related BQ4802Y parallel RTC; detailed feature delta not stated |
| Mounting Type | Surface mount | Surface mount | Surface mount |
Principaux différenciateurs
- Integrated timekeeping and CPU reset supervision (vs BQ4802YDWR)
- Direct parallel access for processor-based equipment (vs BQ4802LYDWR)
- Century-aware calendar support (vs BQ4802YDWR)
Notes de conception
Treat the BQ4802LYDWG4 as a mixed analog and digital timing device: place its supply bypass close to the power and ground connections, keep the parallel clock and data routes short, and avoid routing them directly beneath switching-converter nodes. Follow the exact capacitor placement and bus-routing diagrams in the manufacturer datasheet. Because the supplied records do not contain the pinout or layout drawing, engineers must verify every connection against the current documentation rather than infer it from the 28-pin SOIC outline.
Budget the RTC and any backup source as one complete power path. The verified specification identifies a 3 V Vcc operating condition, but it does not provide operating current, quiescent current, or backup-battery limits. Measure start-up, load, and backup behavior in the assembled system and confirm that the RTC retains valid time through the required power interruption. Do not assume the external NVSRAM-control feature eliminates the need to specify a retention strategy.
A valid-looking calendar read is not necessarily proof that time has been initialized or synchronized. Firmware should validate year, month, day, and time fields, detect implausible values, and establish how the host sets the initial date. Also define supervisor thresholds and restart behavior explicitly. Mixing BQ4802Y and BQ4802LY orderable variants without reviewing their exact thresholds, accuracy, and temperature specifications can create subtle behavioral differences even when the 28-SOIC footprint is unchanged.
The parallel interface trades pin count for short, direct data access. Confirm setup and hold requirements at the system clock, provide clean clock distribution, and avoid adding long stubs or uncontrolled branch loads to address and data lines. Review whether the host loads the bus during reset and whether supervisor outputs can conflict with external reset circuitry. These checks are necessary because the verified snippets identify the interface type but provide no timing table or output-drive details.
Informations de conformité
The supplied verified records do not state RoHS, REACH, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is marked not applicable because no automotive qualification is stated.