NXP Semiconductors PCA1462U/F2,026

Overview

PCA1462U/F2,026 from Philips Semiconductors is a CMOS 32 kHz watch circuit with adaptive motor pulse control for bipolar stepping motors in quartz wristwatches. It features amplitude-regulated oscillator (±0.3×10⁻⁶ frequency stability), EEPROM-based time calibration, on-chip lithium/silver-oxide battery voltage detection (VLIT = 1.80 V typ., VEOL = 1.38 V typ.), and motor step-loss correction via induced voltage sensing. Typical supply current is 170 nA at 1.55 V.

For engineers reviewing the PCA1462U/F2,026 datasheet, PCA1462U/F2,026 pinout, PCA1462U/F2,026 application, or PCA1462U/F2,026 equivalent, key selection criteria include motor pulse adaptability across six stages, end-of-life battery indication, 32 Hz RESET output for timing verification, and chip-scale packaging for ultra-thin watch movement integration.

Technical Context

The PCA1462U/F2,026 integrates a 32.768 kHz crystal oscillator with transconductance gm = 15 µS (typ.) and start-up time ≤1 s, coupled to a dual-mode motor driver that auto-selects silver-oxide (VDD = 1.55 V) or lithium (VDD = 2.1 V) operation based on internal voltage threshold comparison. Its motor control logic executes six pulse stages (1–5, 8) with duty factor tDF = 977 µs and stage-dependent ON/OFF timing-e.g., stage 1 silver-oxide: tON = 550 µs, tOFF = 427 µs.

Motor step integrity is enforced by post-pulse detection: after 1 ms short-circuit to VDD, the circuit measures induced current polarity across 52 measurement cycles (tMC = 488 µs each), requiring ≥1 positive polarity in part 1 and ≥2 subsequent positives after first negative polarity in part 2. Battery end-of-life disables detection and triggers burst-mode stage-8 output (4 pulses every 4 s).

Key Specifications

Pinout & Package

PCA1462U/F2,026 is supplied as a bare die in tray format (chip-in-tray), with bonding pad layout matching the PMFP8 package outline (SOT144-1). Chip area is 2.91 mm²; thickness is 200 ±25 µm. Bonding pads are 110 µm × 110 µm, positioned per Table 3 in datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar watch circuit applications.

Compared with PCA1461U and PCA1463U, the PCA1462U/F2,026 offers balanced pulse timing (5.8 ms) suitable for mid-range torque requirements in standard analog watch movements, maintaining full compatibility with the PCA146x family's calibration, detection, and power management features.

Availability

PCA1462U/F2,026 is available at Aetrix Electronics and suitable for quartz wristwatch movement design, low-power timing module integration, and watch calibration system development requiring stable component supply and long-lifecycle support.

Supply support for PCA1462U/F2,026 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

Philips Semiconductors (now NXP Semiconductors) is a global semiconductor manufacturer specializing in analog, mixed-signal, and RF solutions for consumer, automotive, and industrial markets.

The PCA146x series was designed specifically for battery-operated, quartz-crystal-controlled wristwatches with bipolar stepping motors - prioritizing ultra-low power, motor reliability, and field-calibratable timekeeping accuracy.

FAQ

What is the primary function of the PCA1462U/F2,026 in a quartz watch?

The PCA1462U/F2,026 serves as the core timing and motor driver IC in analog quartz wristwatches. It generates a stable 32.768 kHz oscillation from a quartz crystal, adapts motor pulse width across six stages to match torque demand, detects missed steps via induced voltage sensing, and provides EEPROM-based time calibration. The PCA1462U/F2,026 enables accurate, low-power, and reliable hand movement without external components beyond the crystal and motor.

How does the PCA1462U/F2,026 detect battery end-of-life?

The PCA1462U/F2,026 uses an on-chip voltage detector comparing VDD against VEOL = 1.38 V (typ.). When VDD falls below VEOL, detection and adaptive pulse control are disabled, and the motor output switches to burst-mode stage-8 pulses (4 pulses every 4 s) to indicate end-of-life. This behavior is intrinsic to the PCA1462U/F2,026 and requires no external circuitry.

Can the PCA1462U/F2,026 be reprogrammed for time calibration after assembly?

Yes, the PCA1462U/F2,026 supports up to 100 EEPROM reprogramming cycles using a defined VDD voltage pulse sequence (5.1 V erase, 4.5 V data strobes). This allows field calibration of timekeeping accuracy by inhibiting 8192 Hz pulses - correcting quartz deviations from ±0 to ±127.89×10⁻⁶ in 2.03×10⁻⁶ steps. The PCA1462U/F2,026 retains calibration data without power.

What motor pulse parameters are fixed for the PCA1462U/F2,026?

The PCA1462U/F2,026 has a fixed motor pulse cycle tT = 1 second and fixed pulse width tP = 5.8 ms in stage 2 (silver-oxide mode). While pulse width adapts across stages 1–5 and 8, the base timing interval and stage-2 width are hard-coded characteristics of the PCA1462U/F2,026 variant - distinguishing it from PCA1461U (7.8 ms) and PCA1463U (3.9 ms).

Does the PCA1462U/F2,026 require external components besides the quartz crystal and motor?

No - the PCA1462U/F2,026 requires only a 32.768 kHz quartz crystal (with case connected to VDD) and a bipolar stepping motor. All timing, motor drive, voltage detection, step verification, and calibration functions are integrated. Stray capacitance at M1/M2 must remain <80 pF, and leakage resistance between pins must exceed 20 MΩ, but no resistors, capacitors, or diodes are needed for basic operation of the PCA1462U/F2,026.