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UC3825AN

TIUC3825AN

Texas Instruments
Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull Regulator Positive Output Step-Up, Step-Up/Step-Down DC-DC Controller IC 16-PDIP
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Overview

The UC3825AN is a high-speed PWM controller specifically designed for high-frequency switch-mode power supply applications. It supports both voltage-mode and current-mode control methods, featuring a dual-output totem pole design capable of 2.2A peak current to drive external MOSFET gates directly. With a fast 50ns propagation delay from the PWM comparator to the outputs, it is optimized for high-performance topologies such as push-pull, full-bridge, and half-bridge converters.

Why Choose This Part

The UC3825AN offers a significant speed advantage with its 50ns propagation delay and a wide switching frequency range of 400kHz to 1MHz. Its high-current 2.2A totem pole outputs eliminate the need for external driver stages in many applications, while the low 100-uA startup current improves overall system efficiency during initialization.

Applications

High-Frequency Push-Pull Converters
Utilizes dual totem pole outputs to drive power MOSFETs in isolated DC-DC stages at switching frequencies up to 1MHz.
Full-Bridge and Half-Bridge Power Supplies
Provides the high-speed timing and current drive necessary for high-efficiency bridge topologies in industrial power systems.
Current-Mode Control Modules
Implements pulse-by-pulse current limiting and a latched overcurrent comparator for robust protection in sensitive power electronics.
Boost and Flyback Regulators
Can be configured for single-ended topologies requiring high-speed switching and precise duty cycle control limited to 50 percent.

Key Specifications

Function Step-Up, Step-Up/Step-Down
Topology Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull
Clock Sync No
Output Type Transistor Driver
Mounting Type Through Hole
Output Phases 1
Package / Case 16-DIP (0.300", 7.62mm)
Control Features Current Limit, Frequency Control, Ramp, Soft Start
Duty Cycle (Max) 50%
Number of Outputs 2
Output Configuration Positive
Frequency - Switching 400kHz ~ 1MHz
Operating Temperature 0degC ~ 70degC (TA)
Synchronous Rectifier No
Supplier Device Package 16-PDIP
Voltage - Supply (Vcc/Vdd) 8.4V ~ 22V

Getting Started

To begin design, calculate the timing resistor and capacitor values to set the desired switching frequency between 400kHz and 1MHz. Ensure proper bypass capacitor placement near the Vcc pin (8.4V to 22V range) and use a low-inductance ground plane to manage the high peak currents from the totem pole outputs. Evaluation can be performed using a breadboard with the 16-PDIP package, though high-frequency performance will require a dedicated PCB layout.

UC3825 Family

Comparing specs that differ across variants. The current part is highlighted.

Part Number Package Function Topology Control Features Duty Cycle (Max) Sw. Freq Stock
UC3825AN (this part) DIP-16 Step-Up, Step-Up/S.. Boost, Flyback, Fo.. Current Limit, Fre.. 50% 400k 894
UC3825BDW SOIC-16 — Boost, Buck, Flyba.. Frequency Control,.. — 1M 7,245
UC3825DWTR Tape & Reel SOIC-16 Step-Up, Step-Down.. Buck, Boost, Flyba.. Current Limit, Ena.. 85% 340k 2,002
UC3825DW SOIC-16 Step-Up, Step-Down.. Buck, Boost, Flyba.. Current Limit, Ena.. 85% 340k 594

Also Consider

SG3525AN STMicroelectronics - A widely used, lower-frequency alternative for push-pull applications where 1MHz operation is not required.