NXP Semiconductors PCF8583T/5,512

Overview

PCF8583T/5,512 from NXP Semiconductors is a serial real-time clock and calendar IC with 240 × 8-bit low-voltage RAM, I²C-bus interface (2.5–6.0 V), built-in 32.768 kHz oscillator circuit, and programmable alarm/timer functions. It supports 24-hour or 12-hour format, four-year calendar, and 1 Hz interrupt output - used in industrial control panels, energy meters, and embedded systems requiring battery-backed timekeeping.

For engineers reviewing the PCF8583T/5,512 datasheet, PCF8583T/5,512 pinout, PCF8583T/5,512 application, or PCF8583T/5,512 equivalent, key selection criteria include its dual-voltage operation (1.0–6.0 V for clock, 2.5–6.0 V for I²C), auto-incrementing address register, open-drain INT output, hardware address pin A0, and BCD-encoded time registers with carry-safe read/write.

Technical Context

The PCF8583T/5,512 implements a dedicated clock/calendar core with on-chip 32.768 kHz oscillator driving a frequency divider to generate 100 Hz and 1 Hz timing references. Its 256 × 8-bit RAM includes 8 BCD counter registers (01h–07h), 8 alarm/timer registers (08h–0Fh), and 240 bytes of general-purpose RAM - all accessed via I²C with automatic word address incrementing.

It supports three functional modes: 32.768 kHz clock mode, 50 Hz external reference mode, and event-counter mode (up to 1 million pulses). Alarm logic compares bit-aligned values across date/time registers, while timer overflow and alarm flags trigger the open-drain INT pin when enabled via control/status (00h) and alarm control (08h) registers.

Key Specifications

Pinout & Package

PCF8583T/5,512 uses the SO8 (plastic small outline package; 8 leads; body width 7.5 mm, SOT176-1) with exposed pad connected to VSS per manufacturer mechanical specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1307+T&R and RV-3028-C7, the PCF8583T/5,512 uniquely combines 50 Hz input capability, 240-byte RAM, and event counter mode - making it optimal for utility metering and industrial controllers needing both timekeeping and pulse accumulation in one device.

Availability

PCF8583T/5,512 is available at Aetrix Electronics and suitable for industrial control panels, smart energy meters, and embedded medical devices requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for PCF8583T/5,512 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The PCF8583T/5,512 belongs to NXP's legacy real-time clock product line, designed specifically for cost-sensitive, battery-backed timekeeping in metering, control, and automation systems where reliability and I²C simplicity are prioritized over ultra-low power or high precision.

FAQ

What is the primary function of the PCF8583T/5,512?

The PCF8583T/5,512 is a dedicated real-time clock and calendar IC with integrated 240 × 8-bit RAM, I²C interface, and programmable alarm/timer functions. It maintains accurate time and date in BCD format using either a 32.768 kHz crystal or 50 Hz external input, and delivers time-stamped interrupts via its open-drain INT pin - all while operating from 1.0 V to 6.0 V to support battery backup.

How does the PCF8583T/5,512 handle time reads during BCD carry transitions?

The PCF8583T/5,512 prevents inconsistent reads during BCD carry (e.g., 59 seconds → 00 seconds) by strobing all counter register contents into internal capture latches at the beginning of each read cycle. This ensures that software reads a coherent snapshot of time - a design feature confirmed in Section 7.1 of the NXP datasheet and critical for reliable timestamping in the PCF8583T/5,512.

Can the PCF8583T/5,512 operate with a 50 Hz AC line signal instead of a crystal?

Yes, the PCF8583T/5,512 supports 50 Hz external timing input via the OSCI pin when configured in 50 Hz clock mode (bits 4–5 of control/status register = 01). In this mode, the internal oscillator is disabled, OSCI becomes a high-impedance input, and the device derives timing directly from the 50 Hz signal - enabling mains-synchronized operation in energy meters and building controllers without a crystal.

What is the role of the A0 pin on the PCF8583T/5,512?

The A0 pin on the PCF8583T/5,512 sets the LSB of the I²C slave address, allowing two devices to share the same I²C bus without address conflict. When A0 = VSS, the write address is A0h and read address is A1h; when A0 = VDD, the write address is A2h and read address is A3h - a hardware-configurable feature documented in Table 5 and Section 8.2.1 of the PCF8583T/5,512 datasheet.

Does the PCF8583T/5,512 support both 12-hour and 24-hour time formats?

Yes, the PCF8583T/5,512 supports both formats. The hours register (04h) uses bit 7 as the AM/PM flag and bit 6 to select format: logic 0 = 24-hour mode (AM/PM flag unchanged), logic 1 = 12-hour mode (AM/PM flag updated automatically). This dual-format capability is explicitly defined in Figure 6 and Section 7.4 of the official NXP PCF8583T/5,512 datasheet.