UCC3817AD

Overview

Category: Integrated Circuit (IC)

Use: Voltage Mode PWM Controller

Characteristics: - High-performance voltage mode controller - Designed for use in switch-mode power supplies - Provides precise regulation of output voltage - Offers protection features such as overvoltage and overcurrent protection

Package: SOIC-8

Essence: The UCC3817AD is a voltage mode PWM controller that is widely used in switch-mode power supplies to regulate the output voltage with high precision. It offers various protection features to ensure the safe operation of the power supply.

Packaging/Quantity: The UCC3817AD is available in a small outline integrated circuit (SOIC) package with 8 pins. It is typically sold in reels or tubes containing multiple units.

Specifications

• Input Voltage Range: 4.5V to 16V
• Output Voltage Range: 0V to 5V
• Operating Temperature Range: -40°C to 85°C
• Switching Frequency: Up to 1MHz
• Maximum Duty Cycle: 100%
• Quiescent Current: 2.5mA

Pin Configuration

The UCC3817AD has the following pin configuration:

```

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| | --| VREF |-- --| COMP |-- --| FB |-- --| GND |-- --| RT/CT |-- --| CT/RT |-- --| VCC |-- |___________| ```

• VREF: Reference voltage input
• COMP: Error amplifier output
• FB: Feedback input
• GND: Ground
• RT/CT: Timing resistor/capacitor connection
• CT/RT: Timing capacitor/resistor connection
• VCC: Power supply voltage input

Functional Features

• Voltage mode control for precise regulation of output voltage
• Error amplifier with high gain and low offset voltage
• Adjustable soft-start function to reduce inrush current
• Overvoltage protection to prevent damage to the power supply
• Overcurrent protection to safeguard against excessive load currents
• Under-voltage lockout (UVLO) to ensure proper operation at low input voltages
• Programmable switching frequency for flexibility in design

Advantages and Disadvantages

Advantages: - High-performance controller for efficient power supply designs - Precise voltage regulation for stable output - Protection features enhance system reliability - Adjustable soft-start reduces stress on components during startup - Wide input voltage range allows for versatile applications

Disadvantages: - Limited output voltage range (0V to 5V) - Requires external timing resistor and capacitor for operation - Not suitable for high-power applications due to its small package size

Working Principles

The UCC3817AD operates based on the voltage mode control technique. It compares the feedback voltage (FB) with a reference voltage (VREF) and generates an error signal. This error signal is amplified by the internal error amplifier (COMP) and used to adjust the duty cycle of the PWM signal.

By controlling the duty cycle, the UCC3817AD regulates the output voltage of the power supply. It continuously monitors the feedback voltage and adjusts the duty cycle to maintain the desired output voltage.

The controller also incorporates various protection features such as overvoltage and overcurrent protection. These features help prevent damage to the power supply and connected devices in case of abnormal operating conditions.

Detailed Application Field Plans

The UCC3817AD is commonly used in various switch-mode power supply applications, including:

1. AC-DC power supplies
2. DC-DC converters
3. LED drivers
4. Battery chargers
5. Industrial power supplies

Its high-performance characteristics, precise voltage regulation, and protection features make it suitable for a wide range of applications that require efficient and reliable power conversion.

Detailed and Complete Alternative Models

1. UCC3817AN: Similar to UCC3817AD but available in a DIP-8 package.
2. UCC3817AP: Similar to UCC3817AD but with extended temperature range (-40°C to 125°C).
3. UCC3817AQ: Similar to UCC3817AD but with enhanced ESD protection.

These alternative models offer similar functionality to the UCC3817AD and can be used as replacements depending on specific application requirements.

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