UM3750 Encoder/Decoder Technical Summary

Overview

The UM3750 is a CMOS/LSI digital code Transmitter-Receiver system designed for secure and reliable data communication. It operates in both encoder (transmit) and decoder (receive) modes, making it a versatile solution for applications requiring encoded data transmission. The device is built using advanced CMOS technology, ensuring low power consumption while maintaining high noise immunity and robust performance in various environments.

The UM3750 is particularly well-suited for remote control systems, security applications, and wireless data transmission where encoded signals are necessary to prevent unauthorized access or interference. Its ability to generate and recognize unique digital codes ensures secure communication between transmitter and receiver pairs.

Features

• Dual-function operation as both encoder and decoder
• Low power CMOS technology for energy efficiency
• Wide operating voltage range (typically 3V to 12V)
• High noise immunity for reliable operation in electrically noisy environments
• Programmable address and data inputs for system configuration
• Built-in oscillator requiring minimal external components
• Tri-state output for bus compatibility in decoder mode
• Compact package options for space-constrained applications
• Wide operating temperature range for industrial applications

Applications

The UM3750 finds application in numerous fields where secure digital communication is required:

• Remote Control Systems

  Used in garage door openers, gate controls, and industrial remote control applications where encoded signals prevent unauthorized operation.

• Security Systems

  Implemented in alarm systems, access control, and surveillance equipment to ensure secure communication between components.

• Wireless Data Transmission

  Employed in RF and infrared communication systems requiring encoded data packets for reliable transmission.

• Automotive Electronics

  Used in keyless entry systems, vehicle security, and remote start applications.

• Industrial Automation

  Applied in wireless sensor networks and equipment control where noise immunity and security are critical.

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (VDD): -0.3V to +15V
• Input Voltage (VIN): -0.3V to VDD + 0.3V
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -55°C to +125°C

Recommended Operating Conditions

• Supply Voltage (VDD): 3V to 12V
• Operating Temperature: -20°C to +70°C (commercial grade)
• Input High Voltage (VIH): 0.7VDD min
• Input Low Voltage (VIL): 0.3VDD max

DC Characteristics (VDD = 5V, TA = 25°C)

• Supply Current (Encoder Mode): 0.5mA typical, 1.0mA max
• Supply Current (Decoder Mode): 0.8mA typical, 1.5mA max
• Output High Voltage (VOH): 4.5V min (IOH = -0.4mA)
• Output Low Voltage (VOL): 0.4V max (IOL = 1.6mA)
• Input Leakage Current: ±1μA max

AC Characteristics

• Oscillator Frequency Range: 10kHz to 100kHz (with external RC components)
• Data Rate: Up to 5kbps (dependent on oscillator frequency)
• Propagation Delay: 200ns typical
• Rise/Fall Time: 100ns max

Package Information

The UM3750 is available in multiple package options to suit different application requirements:

16-Pin Dual In-line Package (DIP)

• Package Type: PDIP-16
• Dimensions: 19.30mm x 6.35mm (body)
• Pin Pitch: 2.54mm
• Lead Material: Alloy 42 or equivalent
• Lead Finish: Matte Tin or Gold plating available

16-Pin Small Outline Package (SOP)

• Package Type: SOIC-16
• Dimensions: 9.90mm x 3.90mm (body)
• Pin Pitch: 1.27mm
• Lead Material: Copper alloy
• Lead Finish: Matte Tin or Lead-free options available

Thermal Characteristics

• Thermal Resistance (θJA): 80°C/W (DIP), 120°C/W (SOP)
• Maximum Junction Temperature: 150°C
• Power Dissipation: 500mW max

Functional Description

The UM3750 operates through a combination of internal logic circuits and external configuration components. In encoder mode, the device generates a serial data stream consisting of address and data bits. The decoder mode receives and validates this data stream, providing output only when a valid address match occurs.

Encoder Operation

When configured as an encoder, the UM3750:

• Accepts parallel address and data inputs
• Generates a serial data stream with synchronization pulses
• Repeats the transmission continuously while enabled
• Allows for external oscillator frequency adjustment

Decoder Operation

In decoder mode, the UM3750:

• Receives and processes the serial data stream
• Compares the received address with its own address setting
• Validates the data using internal error checking
• Provides decoded output only when a valid match occurs

Design Considerations

Oscillator Configuration

The UM3750 requires an external resistor and capacitor to set the oscillator frequency. The values should be chosen according to the formula:

f ≈ 1/(2.3 × R × C)

Where R is in ohms and C is in farads. Typical values range from 100kΩ with 100pF for high frequency operation to 1MΩ with 0.01μF for lower frequencies.

Noise Immunity

For optimal noise immunity:

• Keep oscillator components close to the IC
• Use decoupling capacitors (0.1μF) near the power pins
• Implement proper grounding techniques
• Consider shielding in high-noise environments

Power Supply Requirements

The UM3750 operates across a wide voltage range, but performance characteristics vary with supply voltage:

• Lower voltages (3V-5V) for battery-operated applications
• Higher voltages (9V-12V) for improved noise margin in industrial environments
• Voltage regulation recommended for critical applications

Conclusion

The UM3750 Encoder/Decoder IC provides a robust and flexible solution for secure digital communication in various applications. Its dual-mode operation, low power consumption, and high noise immunity make it particularly suitable for remote control and security systems. With proper implementation and attention to design considerations, the UM3750 can deliver reliable performance in demanding environments.