UC3845 Current Mode PWM Controller IC DIP-8

UC3845 is a high-performance fixed-frequency current-mode PWM controller IC, optimized for off-line and DC-DC converter applications. It offers fast over-current protection, low start-up current, and precise duty cycle control. Packaged in a DIP-8 format, it is ideal for use in SMPS, battery chargers, and industrial power supplies.

Key Features of UC3845 Current Mode PWM Controller IC:

• Fixed Frequency Operation: Offers stable 100kHz oscillator for consistent switching.
• Current Mode Control: Enables cycle-by-cycle current limiting for reliable protection.
• Low Start-Up Current: Minimizes loss during initial power-up.
• Trimmed Oscillator: Accurate duty cycle and frequency control with tight tolerance.
• Under-Voltage Lockout (UVLO): Ensures startup only at safe voltage levels.
• Totem Pole Output: Drives high-speed MOSFETs directly.

Technical Specifications of UC3845:

• Operating Voltage Range: 8.5V to 30V
• Oscillator Frequency: 100kHz typical
• Start-Up Current: 0.5mA max
• Operating Supply Current: 11mA typical
• Output Voltage Swing: 0.3V (low) to Vcc – 1.2V (high)
• Current Sense Threshold: 1V typical

Mechanical Specifications of UC3845:

• Package Type: DIP-8 (Dual Inline Package)
• Pin Pitch: 2.54mm
• Body Material: Molded epoxy resin
• Mounting Type: Through-hole

Dimensions:

• Body Width: 7.62mm
• Body Length: 9.8mm
• Height: 3.5mm
• Lead Pitch: 2.54mm

Mounting Options:

• Through-Hole Mount: Ideal for PCBs with DIP socket or direct soldering.

Schematic Diagram, Connection, Wiring and Pinout of UC3845:

• Pin 1 (Comp): Compensation input
• Pin 2 (VFB): Feedback input
• Pin 3 (CS): Current sense input
• Pin 4 (RT/CT): Oscillator timing resistor/capacitor
• Pin 5 (GND): Ground
• Pin 6 (Output): Drive output to MOSFET
• Pin 7 (Vcc): Supply voltage
• Pin 8 (Vref): 5V reference output

Datasheet of UC3845:

• Download UC3845 Datasheet (PDF)

Applications of UC3845:

• Switch Mode Power Supplies (SMPS): Used for efficient AC-DC or DC-DC conversion.
• Battery Chargers: Controls constant current and voltage regulation.
• DC Motor Drivers: Offers PWM control and over-current protection.
• Telecom Power Systems: Provides stable power control for communication devices.
• Industrial Power Equipment: Suitable for wide voltage and current regulation.

Equivalent of UC3845:

• UC3842: Similar IC with different UVLO thresholds
• TL3845: Low power consumption alternative
• SG3525: Dual-output PWM controller for advanced applications

Package Includes:

• 1 x UC3845 Current Mode PWM Controller IC DIP-8