NXP Semiconductors PCF8579H/1,157

Overview

PCF8579H/1 from NXP Semiconductors is a low-power CMOS LCD column driver IC designed for dot matrix graphic displays at 1:8, 1:16, 1:24 or 1:32 multiplex rates. It provides 40 column outputs, 1280-bit display RAM, I²C-bus interface, and operates with logic supply from 2.5 V to 6 V and LCD supply up to 9 V. It functions as the column-side component in conjunction with PCF8578 row driver for full-display control in industrial terminals and automotive information systems.

For engineers reviewing the PCF8579H/1 datasheet, PCF8579H/1 pinout, PCF8579H/1 application, or PCF8579H/1 equivalent, key selection criteria include its 64-pin LQFP package, selectable bias configuration (5 or 6 levels), cascading support for up to 32 devices on one I²C-bus, bank-switching display RAM, and compatibility with microcontrollers via standard two-wire I²C protocol.

Technical Context

The PCF8579H/1 implements a synchronized cascade architecture where SYNC output from one device clocks the next, enabling precise timing alignment across multiple drivers. Its internal 32 × 40-bit static RAM is organized into four 40-byte banks, with auto-incremented addressing and hardware subaddressing (A0–A3) for selective access in multi-device configurations.

It relies on external bias voltages (V3, V4) and VLCD to generate optimal RMS on/off voltages per multiplex rate - e.g., 0.478×Voper and 0.261×Voper for 1:8, or 0.850×Voper and 0.150×Voper for 1:32 - ensuring maximum LCD contrast without integrated charge pumps or voltage regulators.

Key Specifications

Pinout & Package

PCF8579H/1 uses a plastic low-profile quad flat package (LQFP64) with 64 leads, body size 10 × 10 × 1.4 mm (SOT314-2). Pin functions are validated per NXP datasheet Rev. 05 (May 2009).

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCF8579T/1 and PCF8579HT/1, the PCF8579H/1 offers the largest thermal pad area and highest power dissipation margin (400 mW) among the three variants - making it optimal for sustained operation in industrial ambient temperatures up to +85°C.

Availability

PCF8579H/1 is available at Aetrix Electronics and suitable for automotive information systems, point-of-sale terminals, and industrial computer terminals requiring stable component supply and long-term design continuity.

Supply support for PCF8579H/1 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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The PCF8579H/1 belongs to NXP's legacy LCD driver product line, engineered specifically for high-reliability, low-power dot matrix display systems requiring precise multiplex timing and cascaded scalability.

FAQ

What is the maximum number of PCF8579H/1 devices that can operate on a single I²C-bus?

The PCF8579H/1 supports up to 32 devices on one I²C-bus by using two slave addresses (0x78 and 0x79), selected via the SA0 pin. Each address supports 16 uniquely subaddressed units (A0–A3), enabling large-format displays without bus arbitration complexity. This capability is confirmed in Section 8.7.2 and Table 16 of the NXP datasheet Rev. 05.

Does the PCF8579H/1 integrate LCD bias generation or require external components?

The PCF8579H/1 does not integrate bias generation circuitry. It requires external resistor networks connected to V3 and V4 pins to set precise bias voltage ratios (e.g., 0.600×Voper for 1:16 multiplex), as defined in Table 4 of the datasheet. VLCD supplies the high-voltage rail, and VDD powers the logic core independently - confirming fully external bias control for application-specific optimization.

How does the PCF8579H/1 handle display RAM access for multi-device configurations?

The PCF8579H/1 uses hardware subaddressing (A0–A3 pins) to select individual units within a cascade. Only the device whose 4-bit subaddress matches the value sent via the device-select command responds to subsequent RAM-access or load-X-address commands. This ensures deterministic, non-conflicting RAM writes across up to 16 PCF8579H/1 units sharing one I²C address - verified in Sections 8.7.2 and Table 10.

What is the purpose of the SYNC pin on the PCF8579H/1, and how is it used?

The SYNC pin (Pin 9) is a cascade synchronization output that propagates timing pulses from the PCF8578 row driver to chained PCF8579H/1 column drivers. It ensures frame-aligned column updates across all devices, eliminating inter-device skew. As shown in Figure 6 and described in Section 8.4, SYNC must be connected to the CLK input of the next PCF8579H/1 in the chain for proper multiplex timing coordination.

Can the PCF8579H/1 operate standalone without the PCF8578 row driver?

No - the PCF8579H/1 is designed exclusively as a column driver and requires the PCF8578 row driver for complete display control. The block diagram (Figure 1), functional description (Section 8), and application notes confirm co-dependency: PCF8579H/1 receives SYNC and row timing from PCF8578, while PCF8578 decodes display data and drives row electrodes. Neither device functions autonomously in a full LCD system.