PCF1178C is a 4-digit duplex LCD car clock chip with features such as voltage regulation, time calibration, and LCD voltage adjustment with temperature.
The PCF1178C is a single-chip, 4.19 MHz CMOS car clock circuit designed to drive a 4-digit duplex liquid crystal display (LCD). It features an internal voltage regulator that is electrically programmable for various LCD voltages and includes time calibration that is also electrically programmable via an on-chip EEPROM, eliminating the need for trimming capacitors. The device operates in either 12-hour or 24-hour modes and is battery-operated via an internal voltage regulator and an external resistor.
The circuit provides hours, minutes, and seconds functions controlled by two external single-pole, single-throw switches. It includes features such as a temperature-compensated LCD voltage adjuster for good contrast, a 1 Hz set mode, and a test speed-up mode. The document provides comprehensive information on pin configurations, functional descriptions, operating conditions, limiting values, and programming procedures for the device.
| Oscillator Frequency | 4.19 MHz |
|---|---|
| Operating Ambient Temperature | -40 to +85 °C |
| Package Type | 28-lead plastic SMD (SO28) |
| Supply Voltage Range | 3 to 6 V |
| Supply Current | 700 µA (typical) |
| Crystal Frequency Tolerance | ±30×10⁻⁶ |
| External Capacitance | 47 µF |
The mode is selected by connecting the MODE pin to V DD for 12-hour mode or to V SS for 24-hour mode.
Programming is enabled by setting SEL to open-circuit and applying a level of V DD−5 V to V PP.
Connecting TS to V SS stops all counters for quick testing of the display, while connecting it to V DD enables normal operation.