NXP Semiconductors PCF85363ATT1/AJ

Overview

PCF85363ATT1/AJ from NXP Semiconductors is a TSSOP10-packaged, I²C-compatible real-time clock/calendar IC with 64-byte battery-backed RAM, dual alarms, timestamp capture on power loss, and stopwatch mode supporting elapsed time up to 999,999 hours. It operates from 0.9 V to 5.5 V and draws only 0.28 µA typical at 3.0 V - enabling long-term backup in printers, network devices, and white goods.

For engineers reviewing the PCF85363ATT1/AJ datasheet, PCF85363ATT1/AJ pinout, PCF85363ATT1/AJ application, or PCF85363ATT1/AJ equivalent, key selection criteria include its TSSOP10 package with dedicated TS (timestamp/INTB) and CLK output pins, programmable oscillator load capacitance (6/7/12.5 pF), and dual interrupt outputs (INTA open-drain, INTB push-pull) for alarm and periodic event signaling.

Technical Context

The PCF85363ATT1/AJ implements a fully autonomous RTC core with BCD-coded time registers (100th seconds through years), auto-incrementing I²C address pointer, and hardware freeze-on-read to prevent carry corruption during time reads. Its oscillator circuit supports configurable crystal load capacitance and includes offset calibration for ±10 ppm accuracy tuning.

It features three timestamp registers triggered by battery switchover or external TS input, two independent alarm engines (Alarm 1: sec–month; Alarm 2: min–weekday), and a watchdog timer with programmable timeout. The device switches seamlessly between VDD and VBAT supply without software intervention, maintaining time and RAM contents during main power loss.

Key Specifications

Pinout & Package

PCF85363ATT1/AJ uses a plastic thin shrink small outline package (TSSOP10) with 0.5 mm pitch, 3 mm body width, and exposed pad (not electrically connected). Pin 1 is marked by index area; pin numbering follows standard TSSOP convention.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar real-time clock applications.

Compared with PCF85363ATT1/AJ, PCF85363ATT1/AZ offers identical electrical and functional behavior with assured supply chain continuity, while DS3231SN#T&R trades stopwatch capability and timestamp flexibility for superior oscillator stability - making it suitable only for pure high-accuracy RTC use cases.

Availability

PCF85363ATT1/AJ is available at Aetrix Electronics and suitable for printers, network equipment, and white goods requiring stable component supply with long-term industrial temperature support (−40 °C to +85 °C).

Supply support for PCF85363ATT1/AJ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in low-power mixed-signal design.

The PCF85363A product line delivers ultra-low-power RTCs optimized for battery-backed operation, timestamp integrity, and system-level event logging - targeting applications where time persistence and power resilience are non-negotiable.

FAQ

What is the primary function of the TS (CLK/INTB) pin on the PCF85363ATT1/AJ?

The TS (CLK/INTB) pin on the PCF85363ATT1/AJ is a multifunction terminal supporting three modes: timestamp input (triggered by falling edge), programmable clock output (32.768 kHz to 1 Hz), or interrupt output (INTB, push-pull). Its behavior is controlled by the TSPM[1:0] bits in the Pin_IO register (27h), allowing dynamic reconfiguration without hardware change. This flexibility makes PCF85363ATT1/AJ adaptable to diverse timing and event-capture requirements.

Does the PCF85363ATT1/AJ support both 12-hour and 24-hour time formats?

Yes, the PCF85363ATT1/AJ supports both 12-hour and 24-hour time formats. The format is selected via the 12_24 bit in the Oscillator register (25h): when set to 1, hours are encoded in 12-hour mode with AMPM bit indicating AM/PM; when cleared to 0, hours use 24-hour format. All time registers (including alarms and timestamps) follow the selected mode, and the PCF85363ATT1/AJ handles leap-year compensation automatically in RTC mode.

How does the PCF85363ATT1/AJ handle time reads to prevent corruption during carry events?

The PCF85363ATT1/AJ prevents time corruption during carry events by freezing all RTC time registers (00h–07h) at the start of any I²C read transaction. This hardware freeze ensures that sequential reads of seconds, minutes, hours, etc., return a consistent snapshot - eliminating race conditions caused by rollovers mid-read. Engineers must read or write the full time/date block (100th seconds through years) in a single I²C burst to maintain atomicity, a requirement explicitly enforced by the PCF85363ATT1/AJ's architecture.

Can the PCF85363ATT1/AJ operate solely on battery power without VDD present?

Yes, the PCF85363ATT1/AJ can operate continuously on VBAT alone when VDD is absent or below the switchover threshold (~1.1 V). In this mode, it maintains real-time clock operation, alarm functionality, 64-byte RAM retention, and timestamp capture - drawing only 0.28 µA typical. The device automatically resumes VDD-supplied operation when main power returns, with no reset or configuration loss. This behavior is intrinsic to the PCF85363ATT1/AJ's battery switchover circuit and requires no external diodes or control logic.

What crystal load capacitance options does the PCF85363ATT1/AJ support?

The PCF85363ATT1/AJ supports three selectable crystal load capacitances: 6 pF, 7 pF, and 12.5 pF - configured via the CL[1:0] bits in the Oscillator register (25h). This allows optimization for common 32.768 kHz tuning fork crystals without external load capacitors, reducing BOM count and PCB area. The selection directly affects oscillation stability and startup time, with higher CL values generally improving robustness across temperature and voltage variations in the PCF85363ATT1/AJ's oscillator circuit.