NXP Semiconductors PCF1178CT,112

Overview

PCF1178CT,112 from Philips Semiconductors is a CMOS 4-digit duplex LCD car clock IC with integrated 4.19 MHz oscillator, programmable internal voltage regulator (3–6 V), electrically programmable time calibration, and −40 to +85 °C operating range. It drives automotive dashboard clocks using two SPST switches for hour/minute setting and supports 12- or 24-hour display modes.

For engineers reviewing the PCF1178CT,112 datasheet, PCF1178CT,112 pinout, PCF1178CT,112 application, or PCF1178CT,112 equivalent, key selection considerations include its SO28 package, EEPROM-based LCD voltage and time calibration, temperature-compensated backplane generation, and dual-mode timekeeping architecture optimized for battery-powered vehicle instrumentation.

Technical Context

The PCF1178CT,112 implements a 4.194304 MHz crystal oscillator with ±30 ppm tolerance, feeding a programmable divider chain to generate precise 1 Hz timing and multiplexed LCD drive signals. Its internal voltage regulator adjusts output (3–6 V) based on ambient temperature to maintain LCD contrast across −40 to +85 °C.

It uses 1:2 duplex multiplexing with three-level backplane outputs (BP1/BP2) and segment drivers delivering V_ON(RMS) = 0.79 V_DD and V_OFF(RMS) = 0.35 V_DD, enabling low-power, high-contrast 4-digit LCD operation without external bias components.

Key Specifications

Pinout & Package

PCF1178CT,112 is housed in a 28-lead plastic small outline package (SO28), SOT136-1, body width 7.5 mm, with gull-wing leads and standard JEDEC MS-013AE footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LCD car clock applications.

Compared with PCF1178CT,112, PCF1177T,112 reduces display capability but lowers system complexity, while PCF1187T,112 extends functionality to calendar support at the cost of higher current draw and larger firmware overhead-neither is pin-compatible, but all share identical programming methodology and thermal performance.

Availability

PCF1178CT,112 is available at Aetrix Electronics and suitable for automotive dashboard instrumentation, aftermarket infotainment displays, and commercial vehicle telematics systems requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.

Supply support for PCF1178CT,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 global semiconductor leader specializing in automotive, industrial, and consumer ICs with emphasis on mixed-signal integration and system-on-chip solutions.

The PCF1178CT,112 belongs to Philips' car clock IC family designed specifically for cost-sensitive, battery-operated automotive LCD displays-prioritizing EEPROM-programmable calibration, temperature compensation, and minimal external component count.

FAQ

What is the primary function of the PCF1178CT,112 in automotive systems?

The PCF1178CT,112 serves as a dedicated 4-digit duplex LCD car clock IC, integrating timekeeping (hours/minutes/seconds), 12-/24-hour mode selection, colon control, and temperature-compensated LCD drive in a single SO28 package. It replaces discrete oscillator, counter, and display driver circuits, reducing design complexity and bill-of-materials cost in automotive dashboard and infotainment applications.

How does the PCF1178CT,112 achieve temperature-stable LCD contrast?

The PCF1178CT,112 achieves temperature-stable LCD contrast through an electrically programmable internal voltage regulator that adjusts V_DD output based on ambient temperature: it delivers 3–4 V at +85 °C and 5–6 V at −40 °C (when programmed to 4.5 V at 25 °C). This automatic scaling maintains optimal RMS segment voltages (V_ON = 0.79 V_DD, V_OFF = 0.35 V_DD) across the full −40 to +85 °C operating range, eliminating manual contrast adjustment.

Can the PCF1178CT,112 be calibrated for crystal oscillator accuracy?

Yes, the PCF1178CT,112 supports electrical time calibration via its on-chip EEPROM. By applying pulses to the DATA pin while SEL and VPP are configured per Fig.6, users can store a trim count (0–31) that inhibits 262144 Hz oscillator pulses to correct crystal frequency deviation up to ±117.8 ppm. This enables factory or field calibration without trimming capacitors, achieving ±15 s/day accuracy after adjustment.

What are the key differences between PCF1178CT,112 and PCF1177T,112?

The PCF1178CT,112 supports 4-digit duplex LCD with AM/PM, colon control (FLASH pin), and full 12-/24-hour mode, while PCF1177T,112 drives only 3-digit displays without colon or AM/PM segments. Both share identical SO28 packaging, EEPROM programming interface, and temperature-compensated voltage regulation-but PCF1177T,112 lacks the FLASH, AM/PM, and COL pins, making it unsuitable for applications requiring time format indicators.

Does the PCF1178CT,112 require external passive components for basic operation?

The PCF1178CT,112 requires only a 4.194304 MHz crystal between OSC IN and OSC OUT, a series resistor (e.g., 6.8 kΩ) for VDD current limiting from 12 V battery, and a 47 µF external capacitor (C_ext) on VDD for supply stabilization. No external trimming capacitors, pull-up resistors (S1/S2/TS/SEL/DATA have internal 45–180 kΩ), or LCD bias circuitry is needed-enabling true single-chip clock implementation.