NXP Semiconductors PCF8579T/1,118

Overview

PCF8579T/1,118 from NXP Semiconductors is a low-power CMOS LCD column driver IC designed for dot matrix graphic displays at 1:8 to 1:32 multiplex rates. It provides 40 column outputs, 1280-bit display RAM (32 × 40 bits), I²C-bus interface, and operates with logic supply from 2.5 V to 6 V and LCD supply up to 9 V. It is used with PCF8578 row driver in automotive information systems and industrial terminals.

For engineers reviewing the PCF8579T/1,118 datasheet, PCF8579T/1,118 pinout, PCF8579T/1,118 application, or PCF8579T/1,118 equivalent, key selection factors include its 40-column drive capability, selectable 1:8/1:16/1:24/1:32 multiplexing, hardware subaddressing (A0–A3), dual I²C slave address support via SA0, and compatibility with PCF8578 for scalable dot matrix display systems.

Technical Context

The PCF8579T/1,118 functions exclusively as an LCD column driver synchronized to the PCF8578 row driver via the SYNC signal. Its internal timing generator relies on external synchronization pulses rather than an internal oscillator, and it uses a 4-bit hardware subaddress (A0–A3) to uniquely identify up to 16 cascaded devices per I²C slave address.

It implements auto-incremented RAM addressing across hardware subaddress boundaries when paired with PCF8578, supports three RAM access modes (character/half-graphic/full-graphic), and features Power-On Reset that initializes display blanking, 1:32 multiplex rate, bank 0 selection, and X/Y address pointer to (0,0).

Key Specifications

Pinout & Package

PCF8579T/1,118 is supplied in a plastic very small outline package (VSO56, SOT190-1) with 56 leads, optimized for single-plane PCB routing in multi-device LCD driver layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LCD column driver applications.

Compared with PCF8579T/1,118, PCF8579H/1 offers superior thermal performance in space-permitting layouts, while PCF8579HT/1 delivers identical functionality in a lower-profile package - both retain full electrical and functional compatibility but require PCB redesign due to differing footprints.

Availability

PCF8579T/1,118 is available at Aetrix Electronics and suitable for automotive information systems, industrial computer terminals, and point-of-sale terminals requiring stable component supply and long-term manufacturing continuity.

Supply support for PCF8579T/1,118 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 PCF8579 belongs to NXP's legacy LCD driver product line, engineered specifically for low-power, high-reliability dot matrix display systems in harsh environments - emphasizing robust I²C communication, flexible multiplexing, and seamless integration with PCF8578 row drivers.

FAQ

What is the primary function of the PCF8579T/1,118 in an LCD system?

The PCF8579T/1,118 serves exclusively as an LCD column driver IC, providing 40 column outputs (C0–C39) to interface with dot matrix graphic LCDs. It must be used in conjunction with the PCF8578 row driver to form a complete display controller solution. Its role is to convert display RAM contents into column drive waveforms synchronized to the PCF8578's row scanning, supporting multiplex rates from 1:8 to 1:32.

How does the PCF8579T/1,118 handle multiple device cascading?

The PCF8579T/1,118 supports cascading through hardware subaddressing (A0–A3 pins) and dual I²C slave addressing (via SA0). Up to 16 devices can share one slave address using unique 4-bit subaddresses; up to 32 devices total are supported on one I²C bus using both addresses (0x78 and 0x79). The SYNC pin ensures timing coherence across the chain.

What are the valid multiplex rates supported by the PCF8579T/1,118 and how are they selected?

The PCF8579T/1,118 supports four discrete multiplex rates: 1:8, 1:16, 1:24, and 1:32. These are selected dynamically via bits M[1:0] in the "set-mode" I²C command (00 = 1:32, 01 = 1:8, 10 = 1:16, 11 = 1:24). The selected rate determines required LCD bias voltage levels (V3/V4) and impacts display contrast and power efficiency.

Does the PCF8579T/1,118 include internal display memory, and what is its organization?

Yes, the PCF8579T/1,118 contains 1280 bits of static display RAM organized as 32 rows × 40 columns. This RAM is divided into four 40-byte banks (bank 0 to bank 3), each corresponding to a 32-bit display segment. Bank selection is controlled by the "set-start-bank" command and enables features like double buffering and vertical scrolling.

What is the purpose of the TEST pin on the PCF8579T/1,118 and how should it be connected?

The TEST pin (Pin 6) is a factory test function pin and must be connected to VSS (ground) in all application circuits. It is not used during normal operation and has no functional role in display driving or I²C communication. Leaving it unconnected may cause undefined behavior or violate device specifications.