UCC3805D

Overview

Category: Integrated Circuit (IC)

Use: Voltage Mode PWM Controller

Characteristics: - High-performance voltage mode controller - Designed for use in offline and DC-to-DC power supplies - Provides necessary features to implement off-line or DC-to-DC fixed-frequency current-mode control schemes - Suitable for low-power applications

Package: SOIC-8

Essence: UCC3805D is a voltage mode PWM controller that is widely used in various power supply applications. It offers high performance and flexibility in implementing different control schemes.

Packaging/Quantity: UCC3805D is available in a standard SOIC-8 package. It is typically sold in reels of 2500 units.

Specifications

• Supply Voltage Range: 7V to 30V
• Operating Temperature Range: -40°C to 85°C
• Oscillator Frequency Range: 50kHz to 500kHz
• Maximum Duty Cycle: 100%
• Output Current: ±1A
• Error Amplifier Gain Bandwidth Product: 2.5MHz

Pin Configuration

UCC3805D has the following pin configuration:

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| | --| VREF GND|-- Pin 1: Reference Voltage Input --| COMP FB |-- Pin 2: Compensation Node and Feedback Input --| CS RT |-- Pin 3: Current Sense Input and Timing Resistor --| SS OUT |-- Pin 4: Soft Start and Output --| INV VCC |-- Pin 5: Inverting Input and Supply Voltage --| NC NC |-- Pin 6: No Connection --| NC NC |-- Pin 7: No Connection --| NC NC |-- Pin 8: No Connection |___________| ```

Functional Features

• Voltage mode control with fixed-frequency operation
• Internal soft-start for controlled startup
• Error amplifier with high gain bandwidth product for precise regulation
• Current sense input for current limiting and protection
• Overvoltage protection
• Undervoltage lockout
• Adjustable oscillator frequency

Advantages and Disadvantages

Advantages: - High-performance voltage mode controller - Flexible and versatile in implementing different control schemes - Suitable for low-power applications - Provides necessary features for offline and DC-to-DC power supplies - Internal soft-start for controlled startup - Overvoltage protection and undervoltage lockout for enhanced safety

Disadvantages: - Limited output current capability (±1A) - Restricted operating temperature range (-40°C to 85°C)

Working Principles

UCC3805D operates as a voltage mode PWM controller, which means it regulates the output voltage by comparing it to a reference voltage and adjusting the duty cycle of the PWM signal accordingly. It uses an internal error amplifier to compare the feedback voltage with the reference voltage and generate an error signal. This error signal is then fed into the PWM comparator, which compares it with a sawtooth waveform generated by the internal oscillator. The resulting PWM signal controls the power switch, regulating the output voltage.

Detailed Application Field Plans

UCC3805D finds extensive application in various power supply designs, including: - Offline power supplies - DC-to-DC converters - Battery chargers - LED drivers - Industrial control systems - Telecommunications equipment - Consumer electronics

Detailed and Complete Alternative Models

Some alternative models that can be considered as alternatives to UCC3805D are: - UC3842: Voltage mode PWM controller with higher output current capability - TL494: PWM controller with adjustable frequency and duty cycle - SG3525: PWM controller with built-in oscillator and error amplifier - IRS2153D: High-voltage, high-speed power MOSFET and IGBT driver

These alternative models offer similar functionality and can be used as substitutes depending on specific application requirements.

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