Diodes Incorporated PT7C43390LEX

Overview

PT7C43390 from Diodes Incorporated is a CMOS I²C-bus real-time clock IC with auto-calendar support up to year 2099, built-in 32.768 kHz crystal oscillator circuit, and dual interrupt outputs (INT1/INT2). It operates from 1.35 V to 5.5 V, consumes only 0.3 µA typical at 3.0 V, and maintains timekeeping down to 1.25 V - enabling robust backup operation in battery-powered systems such as IP cameras and car navigation units.

For engineers reviewing the PT7C43390 datasheet, PT7C43390 pinout, PT7C43390 application, or PT7C43390 equivalent, key selection criteria include its dual-alarm capability, programmable square-wave output (1 Hz to 32.768 kHz), on-chip clock calibration (±2 ppm achievable), and support for BCD-coded real-time data registers with automatic leap-year calculation.

Technical Context

The PT7C43390 integrates a precision 32.768 kHz oscillator with internal load capacitors (5 pF each), supporting external crystals with CL = 6 pF or 12.5 pF via recommended C1/C2 values. Its clock correction register enables fine-tuning across ±10 ppm IC-to-IC deviation and ±3 ppm voltage-induced drift, allowing temperature-compensated accuracy when paired with an external sensor.

It implements two independent alarm subsystems (Alarm 1/Alarm 2), each configurable via Status Register 2 to trigger INT1 or INT2 with selectable modes: alarm match, periodic minute interrupts, or user-defined frequency output. The I²C interface supports standard (100 kHz) and fast-mode (400 kHz) speeds with NCH open-drain SDA/INT pins requiring external pull-ups.

Key Specifications

Pinout & Package

Available in three RoHS-compliant, lead-free packages: 8-pin SOIC (W), 8-pin TSSOP (L), and 2×3 mm TDFN (ZE). All variants share identical pin functions and electrical behavior.

Key Features

Applications

Equivalent & Alternatives

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

Compared with RV-3028-C7 and PCF8563, the PT7C43390 uniquely combines built-in oscillator, dual alarms, programmable outputs, and voltage-monitoring flags in a single 8-pin package - making it optimal for space-constrained, feature-rich embedded systems needing autonomous time management.

Availability

PT7C43390 is available at Aetrix Electronics and suitable for IP camera systems, car navigation units, and smart energy meters requiring stable component supply, long-term lifecycle support, and automotive-qualified sourcing options.

Supply support for PT7C43390 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

Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal solutions for industrial, computing, consumer, and automotive markets.

The PT7C43390 belongs to Diodes' precision timing product line, engineered for high-accuracy, low-power real-time clock applications in battery-backed and automotive environments where reliability and voltage resilience are critical.

FAQ

Does the PT7C43390 require an external crystal?

No - the PT7C43390 integrates a 32.768 kHz crystal oscillator circuit with internal 5 pF load capacitors on XIN and XOUT. An external crystal is optional and only needed if higher stability or custom frequency tolerance is required. When used, CL = 6 pF or 12.5 pF crystals are supported with recommended external C1/C2 values.

How does the clock calibration function improve accuracy?

The PT7C43390 includes a 7-bit clock correction register that adjusts the oscillator's effective frequency by ±10 ppm in 0.95 ppm steps. When calibrated at 25°C using factory-trimmed values or user measurement, total accuracy improves to better than ±2 ppm - sufficient for most industrial and automotive timestamping without external compensation.

Can both INT1 and INT2 pins output the same alarm event?

No - INT1 and INT2 are independently configurable via Status Register 2. Each pin can be assigned to Alarm 1, Alarm 2, periodic interrupt, or programmable square-wave output. Simultaneous identical outputs require external logic; the IC enforces exclusive assignment per pin to prevent signal contention.

What happens to timekeeping during a power transition from main supply to backup battery?

Timekeeping continues uninterrupted if VDD remains ≥1.25 V. The PT7C43390 automatically switches to backup mode, preserves real-time data and alarm settings in BCD registers, and asserts the BLD flag when voltage drops below the detection threshold (1.05 V typ.). No host intervention is required for seamless switchover.