NXP Semiconductors PCF8578HT/1,518

Overview

PCF8578HT/1 from NXP Semiconductors is a low-power CMOS LCD row/column driver IC designed for dot matrix graphic displays at 1:8, 1:16, 1:24 or 1:32 multiplex rates. It provides 40 outputs-24 programmable for configurable row/column ratios (32/8, 24/16, 16/24, 8/32)-and integrates 1280-bit display RAM with auto-increment addressing and bank switching. It functions as a stand-alone controller or master driver for up to 32 PCF8579s in large-display systems, communicating via I²C-bus and featuring on-chip oscillator with external resistor tuning.

For engineers reviewing the PCF8578HT/1 datasheet, PCF8578HT/1 pinout, PCF8578HT/1 application, or PCF8578HT/1 equivalent, key selection considerations include its TQFP64 package, 2.5–6 V logic supply, 9 V max LCD supply, selectable bias configuration (5 or 6 levels), and compatibility with microcontrollers requiring minimal I²C communication overhead for display RAM access.

Technical Context

The PCF8578HT/1 implements a mixed-mode or row-mode LCD drive architecture with hardware-controlled multiplex rate selection and dedicated timing generator. Its internal oscillator-tuned by an external resistor on OSC–VSS-feeds a prescaler that generates CLK output at 1/6 (for 1:8/1:16/1:32) or 1/8 (for 1:24) of oscillator frequency, synchronizing cascaded PCF8579s via SYNC.

Display RAM is organized as 32 × 40-bit static memory across four 40-byte banks, accessible only in mixed mode with fixed subaddress 0000. The command decoder supports five I²C-based instructions-including set-mode, set-start-bank, and load-X-address-with continuation bit handling and hardware subaddress filtering for multi-device coordination.

Key Specifications

Pinout & Package

PCF8578HT/1 uses a plastic thin quad flat package (TQFP64) with 64 leads, body size 10 × 10 × 1.0 mm (SOT357-1). Pin layout is optimized for single-plane wiring in multi-device LCD systems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCF8578HT/1, the PCF8578H/1 offers identical functionality in a slightly taller LQFP64 variant, while the PCF8578T/1 requires full mechanical redesign due to different pin count and package type-neither is pin-compatible, but both share the same command set, RAM structure, and I²C protocol.

Availability

PCF8578HT/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 lifecycle support.

Supply support for PCF8578HT/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 focused on secure connectivity solutions for automotive, industrial, and IoT applications.

The PCF8578 series belongs to NXP's legacy LCD controller/driver product line, designed specifically for cost-sensitive, low-power monochrome dot matrix displays in resource-constrained embedded systems.

FAQ

What is the primary function of the PCF8578HT/1 in an LCD system?

The PCF8578HT/1 serves as a dedicated LCD row and column driver IC that manages timing, bias generation, and display data routing for dot matrix graphic displays. It operates in either stand-alone mode for small displays or as a master controller for cascaded PCF8579s in larger systems. Its integrated 1280-bit RAM, I²C interface, and on-chip oscillator enable compact, low-component-count implementations without external clock sources or complex bias networks. The PCF8578HT/1 handles all low-level waveform generation and synchronization, freeing the host microcontroller from display timing overhead.

Does the PCF8578HT/1 require an external crystal or clock source?

No, the PCF8578HT/1 does not require an external crystal. It features an on-chip oscillator whose frequency is set by a single external resistor connected between the OSC pin and VSS. A 330 kΩ resistor yields approximately 12.288 kHz, enabling a nominal 64 Hz frame rate. An external clock may be applied to the CLK pin only if OSC is tied to VDD-but this is optional and not required for standard operation. The PCF8578HT/1's self-contained timing eliminates BOM cost and board space associated with crystals or oscillators.

How many PCF8579 devices can be driven by a single PCF8578HT/1?

A single PCF8578HT/1 can drive up to 32 PCF8579 devices in a cascaded configuration. This is achieved using two distinct I²C slave addresses (selected via SA0) and hardware subaddressing (A0–A3 pins on each PCF8579), allowing up to 16 devices per address. In row mode, the PCF8578HT/1 provides synchronized CLK and SYNC signals to coordinate timing across the entire chain. The combined chipset supports displays up to 40960 dots - for example, 32 rows × 1280 columns - making it suitable for large alphanumeric or graphic panels.

What are the valid multiplex rates supported by the PCF8578HT/1?

The PCF8578HT/1 supports four discrete multiplex rates: 1:8, 1:16, 1:24, and 1:32. Each rate determines the number of active rows per frame and dictates corresponding LCD bias voltage levels (V2–V5) per NXP Table 6. For instance, 1:8 uses 8 row outputs (R0–R7) and requires specific RMS voltage ratios (e.g., V2/Voper = 0.739), while 1:32 activates all 32 programmable outputs (R0–R31/C31) with different bias ratios (e.g., V2/Voper = 0.850). The rate is selected via the M[1:0] bits in the set-mode command and affects display resolution, contrast, and power consumption.

Can the PCF8578HT/1 operate with a 3.3 V logic supply?

Yes, the PCF8578HT/1 fully supports 3.3 V logic supply operation. Its VDD specification ranges from 2.5 V to 6.0 V, making it compatible with standard 3.3 V microcontroller I/O levels without level shifting. The I²C interface (SDA/SCL) operates within this voltage range, and internal logic, RAM, and command decoding function correctly at 3.3 V. Additionally, the 3.3 V supply ensures sufficient noise margin for reliable communication in electrically noisy industrial or automotive environments - a key design advantage confirmed in NXP's characterization data.