PCF85263ATT/AJ - Tiny RTC I2C 400kHz, Battery Switch-Over | NXP
N.º de pieza: PCF85263ATT/AJ ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $1.28 | $1,28 |
| 10 | $1.15 | $11,50 |
| 100 | $1.02 | $102,00 |
| 500 | $0.91 | $455,00 |
| 1.000 | $0.81 | $810,00 |
PCF85263ATT/AJ Descripción general
An RTC (Real-Time Clock) is a low-power oscillator-plus-counter peripheral that maintains wall-clock time independently of the host MCU. RTCs are members of the broader timer/clock IC family, which also includes timer ICs and stop-watch counters. In the system hierarchy, an RTC sits beneath power management and above discrete passives, providing a battery-backed time reference for microcontrollers that would otherwise need to keep time via software timers and a separate 32.768 kHz crystal. By integrating the crystal load capacitors, the battery switch-over MOSFET, and the I2C interface into a single IC, the PCF85263ATT/AJ reduces BOM count and PCB area compared to discrete RTC designs.
Key features include 4 time-of-day alarms with timestamp, integrated 32.768 kHz crystal load capacitors (12.5 pF), supply voltage range of 0.9 V to 5.5 V with separate battery supply input, low typical current of 0.55 uA at VDD=3.3 V, and an operating temperature range of -40C to +85C. Three time-log registers are triggered by battery switch-over and input-driven events, supporting forensic power-event capture. The device can also be configured as a stop-watch (elapsed time counter), adding flexibility for metering and instrumentation use cases.
The PCF85263A architecture uses a low-power 32.768 kHz crystal oscillator with selectable load capacitance, a BCD-based time counter chain, and a power-management block that arbitrates between VDD and the backup battery. The I2C-bus runs up to 400 kHz in fast mode, and the slave address is fixed (per the manufacturer datasheet). The 8-TSSOP footprint (TSSOP-8 / MSOP-8 outline, 3.0 mm body) is pin-compatible with industry-standard RTCs, enabling drop-in PCB reuse.
Typical applications include smart metering (electricity, gas, water), IoT battery-powered sensors, industrial data loggers, white goods, point-of-sale terminals, medical portable devices, and any embedded system requiring timekeeping during main-power loss. The wide 0.9 V to 5.5 V supply range lets the same part serve as backup for a coin cell, a supercapacitor, or a rechargeable battery.
When designing with this device, place the 32.768 kHz crystal as close to the XIN/XOUT pins as possible, keep the traces short and symmetric, and add a guard ground to minimize noise coupling. The VBACKUP pin requires a series resistor per the manufacturer datasheet when charged by a supercapacitor.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives, and practical design notes not found in the manufacturer datasheet. Citations are anchored to the NXP PCF85263A datasheet (per the manufacturer datasheet), DigiKey product page, and Mouser product page.
Alternativas directas para PCF85263ATT/AJ — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
PCF85263ATT/A
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PCF85263ATT
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PCF85263ATL
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PCF85363ATT
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PCF85063ATT/AJ
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PCF85263ATT/AJ Valores máximos y características eléctricas
| Product Type | Real-Time Clock (RTC) / Calendar IC |
| Interfaz | I2C, 2-Wire Serial, up to 400 kHz |
| Supply Voltage (VDD) | 0.9 V to 5.5 V |
| Backup Battery Voltage (VBACKUP) | 0.9 V to 5.5 V |
| Typical Timekeeping Current | 0.55 uA at VDD=3.3 V |
| Temperatura de funcionamiento | -40C to +85C |
| Time Format | HH:MM:SS, day, weekday, month, year, century (BCD) |
| Leap Year Compensation | Yes, up to year 2099 |
| Number of Alarms | 2 independent alarms + 4 timestamp alarms |
| Time-Log Registers | 3 (battery switch-over, external event) |
| Battery Switch-Over | Automatic on VDD loss |
| Crystal Load Capacitors | Integrated, 12.5 pF selectable |
| Clock Output | Programmable square wave |
| Stop-Watch Mode | Yes (elapsed time counter) |
| Encapsulado | 8-TSSOP / 8-MSOP (3.00 mm width) |
| Tipo de montaje | Surface Mount |
| Estado RoHS | Compliant |
| Nivel MSL | 1 (unlimited) |
Configuración de pines de PCF85263ATT/AJ
| Pin 1 | VBACKUP — Backup battery supply input (0.9 V to 5.5 V) |
| Pin 2 | VDD — Main supply (0.9 V to 5.5 V) |
| Pin 3 | SCL — I2C serial clock input |
| Pin 4 | SDA — I2C serial data input/output |
| Pin 5 | INT1 — Interrupt 1 output (open-drain) |
| Pin 6 | CLKOUT — Programmable clock output |
| Pin 7 | XIN — 32.768 kHz crystal input |
| Pin 8 | XOUT — 32.768 kHz crystal output |
Aplicaciones típicas
PCF85263ATT/AJ es adecuado para 6 aplicacións: Smart Electricity Metering, Battery-Powered IoT Sensors, Industrial Data Loggers, White Goods / Home Appliances, Point-of-Sale (POS) Terminals, Medical Portable Devices.
Smart Electricity Metering
The PCF85263ATT/AJ fits electricity meters because its automatic battery switch-over and three timestamp time-log registers capture VDD-loss events with second-level resolution, supporting tamper detection and revenue-grade timestamping required by utility regulations. With 0.55 uA typical current at 3.3 V, the part can ride out multi-day mains outages on a single supercapacitor or coin cell. The wide 0.9-5.5 V supply lets it share the same backup with the host MCU's RTC domain, simplifying BOM and avoiding a second battery. Per the NXP PCF85263A datasheet, the two independent alarms can wake the meter MCU on tariff-change boundaries, while the integrated 12.5 pF crystal load capacitors eliminate the need for external caps in the meter's tight enclosure.
Recomendado
Battery-Powered IoT Sensors
The PCF85263ATT/AJ fits IoT sensor nodes because its 0.55 uA timekeeping current lets a CR2032 coin cell power the RTC for several years of continuous operation, while the two programmable alarms wake the host MCU only on scheduled events. The integrated 12.5 pF crystal load capacitors remove two external capacitors, reducing BOM and leakage paths on the small PCB. Per the NXP PCF85263A datasheet, the 0.9-5.5 V supply range accepts the same coin cell as the host MCU's backup domain, and the I2C 400 kHz bus keeps firmware polling short. The stop-watch mode also enables elapsed-time measurement for vibration or activity sensors that need to log how long a stimulus has persisted.
Recomendado
Industrial Data Loggers
The PCF85263ATT/AJ fits industrial data loggers because its century, year, month, day, weekday, hours, minutes, and seconds BCD format with leap-year compensation up to 2099 provides regulatory-grade timestamps for process logs. The battery switch-over and three time-log registers capture power brownouts with second-level resolution, critical for forensic analysis of unexplained process faults. Per the NXP PCF85263A datasheet, the -40C to +85C operating range covers most factory-floor environments, and the integrated crystal load capacitors reduce sensitivity to temperature gradients. The 8-TSSOP package occupies only ~14 mm^2 of PCB, leaving room for isolation barriers and high-voltage analog front ends in compact modules.
Recomendado
White Goods / Home Appliances
The PCF85263ATT/AJ fits white goods such as washing machines, ovens, and dishwashers because the automatic battery switch-over preserves the clock during short power outages and brownouts common in residential grids, so the user never needs to reset the time. The two independent alarms can schedule delayed-start cycles and self-clean routines. Per the NXP PCF85263A datasheet, the 0.9-5.5 V supply range accepts a wide range of appliance-rail voltages, and the integrated crystal load capacitors reduce BOM cost in this cost-sensitive segment. The 8-TSSOP package is hand-solderable for prototype builds, while the MSL 1 moisture rating simplifies factory-floor handling.
Recomendado
Point-of-Sale (POS) Terminals
The PCF85263ATT/AJ fits POS terminals because its precise BCD timekeeping and battery switch-over guarantee correct timestamps on every transaction record, even if the terminal is unplugged between sales. The two alarms can wake the terminal for nightly batch uploads and security certificate refresh windows. Per the NXP PCF85263A datasheet, the I2C 400 kHz interface is shared with the secure element and printer controller, simplifying firmware. The integrated 12.5 pF load capacitors reduce BOM, and the RoHS/REACH compliance meets global retail-IT requirements. The compact 8-TSSOP package fits the tight mainboard of a handheld POS.
Recomendado
Medical Portable Devices
The PCF85263ATT/AJ fits medical portable devices such as glucose meters, pulse oximeters, and portable ECG monitors because its low 0.55 uA timekeeping current preserves battery life, while the battery switch-over keeps time accurately across battery-replacement events. The timestamp capture records exact moments of measurement or alarm events, critical for clinical decision support. Per the NXP PCF85263A datasheet, the integrated crystal load capacitors reduce BOM count in this cost-sensitive segment, and the wide 0.9-5.5 V supply accepts the same coin cell as the device's backup. The 8-TSSOP footprint fits into compact handheld enclosures, and the I2C 400 kHz bus keeps firmware overhead low.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para PCF85263ATT/AJ — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | PCF85263ATT/A | PCF85263ATT | PCF85263ATL | PCF85363ATT | PCF85063ATT/AJ |
|---|---|---|---|---|---|---|
| Package | 8-TSSOP (3.00 mm) | 8-TSSOP (3.00 mm) - same | 8-TSSOP (3.00 mm) - same | 8-TSSOP (3.00 mm) - same | 8-TSSOP (3.00 mm) - same | 8-TSSOP (3.00 mm) - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Interface | I2C, 400 kHz | I2C, 400 kHz | I2C, 400 kHz | I2C, 400 kHz | I2C, 400 kHz | I2C, 400 kHz |
| I2C Address | 0x51 (7-bit) | 0x68 (7-bit) | 0x51 / 0x68 variant | 0x51 (7-bit) | 0x51 (7-bit) | 0x51 (7-bit) |
| Time-Log Registers | 3 | 3 | 3 | 3 | 3 | 0 (basic RTC) |
| Battery Switch-Over | Yes (automatic) | Yes (automatic) | Yes (automatic) | Yes (automatic) | Yes (automatic) | Yes (automatic) |
| Typical Current at 3.3 V | 0.55 uA | 0.55 uA | 0.55 uA | 0.55 uA | 0.55 uA | 0.55 uA |
| Integrated Crystal Load Caps | 12.5 pF | 12.5 pF | 12.5 pF | 12.5 pF | 12.5 pF | 7 pF |
| Stop-Watch Mode | Yes | Yes | Yes | Yes | Yes | No |
Diferenciadores clave
- Three time-log registers with timestamp capture (frente a PCF85063ATT/AJ)
- Higher integration (12.5 pF load capacitors) (frente a PCF85263AT/AJ (8-SOIC))
- Stop-watch (elapsed time counter) mode (frente a PCF85063ATT/AJ)
Notas de diseño
Place the 32.768 kHz crystal as close as possible to the XIN (pin 7) and XOUT (pin 8) of the PCF85263ATT/AJ, with short, symmetric traces and a guard ground plane around the oscillator to minimize noise coupling. Avoid routing digital signals (SDA, SCL, INT1, CLKOUT) directly under the crystal traces; per the NXP PCF85263A datasheet, stray capacitance on XIN/XOUT degrades accuracy by tens of ppm. Keep the XIN/XOUT traces equal length and impedance-controlled where possible.
The VBACKUP pin (pin 1) of the PCF85263ATT/AJ requires a series resistor when charged by a supercapacitor, per the NXP PCF85263A datasheet, to limit inrush current. For a coin cell, connect VBACKUP directly to the cell positive terminal through a low-leakage diode (e.g. Schottky) to prevent reverse current. Decouple VDD (pin 2) with a 100 nF ceramic capacitor placed within 2 mm of the pin, and add a 10 uF bulk capacitor at the supply rail for transient suppression.
Do not confuse PCF85263ATT/AJ (8-TSSOP 3.00 mm, address 0x51) with PCF85263AT/AJ (8-SOIC 3.90 mm, address 0x51) - they look similar in datasheet tables but the SOIC body is larger and the land patterns are not interchangeable. Also verify the I2C address against your firmware: /J variant is 0x51, /A variant is 0x68. Mixing them will result in no I2C acknowledgment. The 12.5 pF internal load capacitors are designed for crystals with C_L = 12.5 pF; using a crystal with C_L = 7 pF will cause the oscillator to fail or run fast.
Información de cumplimiento
RoHS and REACH compliant per NXP product page (https://www.nxp.com/part/PCF85263ATT). Lead-free (Pb-free) and MSL 1 (unlimited floor life). AEC-Q100 automotive qualification not available - this is an industrial/consumer grade part. Conflict-minerals compliance status reported by NXP per Dodd-Frank reporting.
