NXP Semiconductors PCF8584P,112

Overview

PCF8584P,112 from Philips Semiconductors is a parallel-bus-to-I²C-bus protocol converter IC supporting both master and slave operation, with programmable SCL frequencies up to 90 kHz, −40 to +85 °C operating temperature, and DIP20 package. It enables 8051/68000/Z80 microcontrollers to interface with I²C peripherals in industrial control and embedded instrumentation.

For engineers reviewing the PCF8584P,112 datasheet, PCF8584P,112 pinout, PCF8584P,112 application, or PCF8584P,112 equivalent, key selection considerations include its dual-mode bus interface detection (80XX/68000), long-distance 4-wire mode support, monitor mode capability, interrupt vector programmability, and explicit BER (bus error) flag reporting - all critical for robust multi-master I²C system design.

Technical Context

The PCF8584P,112 implements full I²C protocol handling-including START/STOP generation, arbitration, ACK/NACK control, and clock stretching-via dedicated internal registers (S0–S3) accessed through an 8-bit parallel port. Its register-mapped architecture separates control/status (S1, A0=HIGH) from data/initialization (S0/S0'/S2/S3, A0=LOW), enabling efficient byte-wise I²C transaction management.

It supports three operational modes: standard 2-wire I²C (SDA/SCL bidirectional), long-distance 4-wire mode (SDA OUT/SCL IN/SDA IN/SCL OUT), and passive monitor mode (S0'=00H). Mode selection is hardware- and register-driven: interface type auto-detected on first WR-CS sequence; long-distance mode enabled by ES1=1 with ESO=1; monitor mode activated by zeroing the own address register.

Key Specifications

Pinout & Package

PCF8584P,112 is housed in a plastic dual in-line package (DIP20), 300 mil width, with 20 leads. Pin spacing conforms to JEDEC MS-001, lead finish is matte tin.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C-bus controller applications.

Compared with PCA9564 and PCF8584T, the PCF8584P,112 offers unique long-distance 4-wire and strobe-generation capabilities absent in newer variants, while maintaining full register and timing compatibility with the original Philips I²C controller family - making it irreplaceable for field-repair of legacy industrial equipment relying on those modes.

Availability

PCF8584P,112 is available at Aetrix Electronics and suitable for industrial sensor hubs, legacy MCU I²C bridges, I²C bus monitors, multi-master controllers, and retrofit instrumentation requiring stable component supply across extended product lifecycles.

Supply support for PCF8584P,112 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 pioneer in I²C technology, developing foundational interface ICs for embedded systems interoperability.

The PCF8584P,112 belongs to Philips' early-generation I²C-bus controller product line, designed specifically to enable 8-bit microcontrollers without native I²C peripherals to participate in I²C networks with full protocol compliance and multi-master support.

FAQ

What is the primary function of the PCF8584P,112 in an embedded system?

The PCF8584P,112 serves as a parallel-bus-to-I²C-bus protocol converter, enabling microcontrollers like the 8051 or Z80 to communicate with I²C peripherals. It handles all I²C-specific tasks - including START/STOP generation, arbitration, ACK/NACK, clock stretching, and error detection - freeing the host CPU from low-level timing-critical operations. Its register-mapped architecture allows full control via standard 8-bit parallel bus cycles, making it ideal for legacy and resource-constrained systems where native I²C is unavailable.

How does the PCF8584P,112 detect whether it is interfacing with an 80XX-type or 68000-type microcontroller?

The PCF8584P,112 detects interface type automatically during initialization by monitoring the first WR (or R/W) and CS signal sequence. If a HIGH-to-LOW transition on WR occurs while CS is HIGH, it enters 68000 mode and enables DTACK output; otherwise, it defaults to 80XX mode. This detection is performed once at power-up or reset and requires stable WR and CS signals post-reset. The behavior is documented in Section 6.2 (Interface Mode Control) of the PCF8584P,112 datasheet.

Can the PCF8584P,112 operate in a passive I²C bus monitoring role without interfering with ongoing communication?

Yes - the PCF8584P,112 supports dedicated monitor mode, activated by loading 00H into the own address register S0'. In this mode, it becomes a passive listener: it never transmits ACK, never initiates START/STOP, and does not participate in arbitration. All I²C traffic appears on its internal shift register, and the PIN bit toggles on each received byte's ACK phase, allowing precise timestamped capture. Because it drives no bus lines except internally, it adds negligible capacitance and introduces zero interference - a key advantage of the PCF8584P,112 for debugging and validation.

What are the hardware requirements to use the long-distance mode of the PCF8584P,112?

To use long-distance mode, the PCF8584P,112 must be configured with ESO=1 and ES1=1, and ENI must be cleared to 0 before entry. Pins 2 (SDA OUT), 3 (SCL IN), 4 (SDA IN), and 5 (SCL OUT) become unidirectional and must connect to external line drivers/receivers (e.g., RS-422 transceivers). The PCF8584P,112 node must be isolated from the 4-wire bus via 3-state drivers until fully initialized, or system malfunction may occur. No changes to I²C protocol logic are needed - only physical layer extension.

Does the PCF8584P,112 provide any built-in protection against I²C bus errors, and how is it signaled?

Yes - the PCF8584P,112 includes a dedicated BER (Bus Error) flag in the read-only status section of register S1. It asserts when an illegal START or STOP condition is detected - such as a START while the bus is busy or a STOP without a preceding START. When BER activates, it automatically resets the BB (Bus Busy) flag to 1 (inactive) and forces PIN to 0 (active), triggering an interrupt if ENI is set. This provides immediate, hardware-verified error detection without requiring software parsing of bus waveforms - a critical reliability feature in the PCF8584P,112 for industrial environments.