NXP Semiconductors PCF8583BS,518

Overview

PCF8583BS,518 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), integrated 32.768 kHz oscillator circuit, and programmable alarm/timer functions. It supports 24/12-hour format, four-year calendar, and event counting up to 1 million pulses - deployed in industrial control panels and embedded metering systems requiring battery-backed timekeeping.

For engineers reviewing the PCF8583BS,518 datasheet, PCF8583BS,518 pinout, PCF8583BS,518 application, or PCF8583BS,518 equivalent, key selection criteria include its HVQFN20 package compatibility, dual I²C slave addresses (A0h/A2h write, A1h/A3h read), 1.0 V data retention capability, interrupt-driven alarm signaling, and BCD-encoded counter registers for direct calendar readout without software conversion.

Technical Context

The PCF8583BS,518 implements a dedicated clock/calendar subsystem using an on-chip 32.768 kHz oscillator driving a frequency divider to generate 1 Hz and sub-second timing signals. Its 256 × 8-bit RAM includes 8 bytes for clock counters (00h–07h), 8 bytes for alarm/timer control (08h–0Fh), and 240 bytes of general-purpose RAM - all accessed via auto-incrementing I²C address register.

It operates in three functional modes: 32.768 kHz clock mode (default), 50 Hz reference input mode, and external event-counter mode. Alarm logic compares BCD values across date/time registers with maskable bits (e.g., year/weekday ignored in daily alarms), while the open-drain INT pin asserts active-low on alarm flag, timer overflow, or event match - all software-resettable via control/status register (00h).

Key Specifications

Pinout & Package

HVQFN20 package (SOT662-1), 5 × 5 × 0.85 mm body, thermally enhanced, no leads, exposed die paddle connected to VSS.

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, PCF8583BS,518 offers superior alarm granularity and event counting; versus PCF8563T, it trades lower power for broader legacy support and simpler initialization - making it optimal for cost-sensitive industrial retrofits requiring dated alarms and 50 Hz line synchronization.

Availability

PCF8583BS,518 is available at Aetrix Electronics and suitable for industrial control panels, smart energy meters, embedded HVAC controllers, and medical device log modules requiring stable component supply across extended product lifecycles.

Supply support for PCF8583BS,518 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 PCF8583BS,518 belongs to NXP's legacy real-time clock family designed for robust, low-power timekeeping in resource-constrained embedded systems - emphasizing long-term reliability, wide voltage operation, and I²C simplicity over advanced features like temperature compensation.

FAQ

What is the primary function of the PCF8583BS,518?

The PCF8583BS,518 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 using a 32.768 kHz crystal or 50 Hz input, stores timestamps and application data, and generates interrupt-driven alerts - all within the PCF8583BS,518's HVQFN20 package.

Does the PCF8583BS,518 support battery backup operation?

Yes, the PCF8583BS,518 supports data retention down to 1.0 V supply voltage, enabling continuous timekeeping during main power loss when backed by a coin cell or supercapacitor. Its low operating current (max 50 μA at 0 Hz) extends backup runtime, and the internal oscillator remains functional across the 1.0–6.0 V range specified for clock operation at 0 °C to +70 °C.

How does the PCF8583BS,518 handle alarm conditions?

The PCF8583BS,518 supports dated, daily, weekday, and timer alarms via BCD-matching logic against registers 01h–07h. When triggered, it sets the alarm flag (bit 1 of control/status register 00h) and drives the open-drain INT pin low. The flag persists until cleared by software write, and alarm registers 08h–0Fh become free RAM when alarm is disabled - a behavior confirmed in the PCF8583BS,518 datasheet Section 7.2.

Can the PCF8583BS,518 operate without an external crystal?

Yes, the PCF8583BS,518 can operate in 50 Hz clock mode or event-counter mode with the oscillator disabled. In these modes, OSCI accepts an external 50 Hz AC signal or pulse train, while OSCO is left open-circuit. This eliminates the need for a crystal and associated load capacitors - a verified capability documented in PCF8583BS,518 Section 7.10 and Table 4.

What are the I²C slave addresses for the PCF8583BS,518?

The PCF8583BS,518 uses hardware-addressable I²C slave addresses determined by the A0 pin: A0 = LOW yields write address 0xA0 and read address 0xA1; A0 = HIGH yields write address 0xA2 and read address 0xA3. These fixed 7-bit addresses (with R/W bit appended) are defined in Table 5 of the PCF8583BS,518 datasheet and allow two devices on the same bus without additional logic.