Overview
The UC1823A, UC2823A, UC2823B, UC3823A, UC3823B, UC1825A, UC2825A, UC2825B, UC3825A, UC3825B datasheet details a family of high-speed Pulse Width Modulation (PWM) controllers from Texas Instruments (TI) that operate at practical switching frequencies up to MHz levels. This document, revised in September 2010, introduces improvements upon the standard UC3823 and UC3825 PWM controllers, offering enhancements in several internal circuit blocks.
Features
The controllers are designed to be compatible with both voltage-mode and current-mode control methods, providing versatility in various applications. Key features include:
- A 50-ns propagation delay to output ensures fast response times.
- High-current dual totem pole outputs are capable of delivering 2-A peak currents.
- The internal oscillator discharge current is trimmed for precise dead time control and frequency accuracy within 6%.
- Startup current is exceptionally low at approximately 100 μA, making the controllers well-suited for off-line operations.
- Pulse-by-pulse current limiting, along with a latched overcurrent comparator that includes full-cycle restart, improves system reliability and safety.
- Error amplifier gain bandwidth product of 12 MHz and an input offset voltage of 2 mV promote accurate and stable control.
- Current limit threshold is tightly controlled to within a 5% tolerance.
Description
The improved variants of the UC3823/UC3825 controllers enhance several aspects of performance, notably increasing error amplifier gain bandwidth and reducing input offset voltage. The updated oscillator discharge current specifications contribute to more accurate control over switching dead times.
The output drivers have been engineered to actively sink current during under-voltage lockout (UVLO) without compromising startup current specifications. With each output having the capability of 2-A peak during transitions, these controllers are adept at handling high power loads.
The UC1823A variant specifically features low output toggles Q and QQ, providing an additional adaptation for specific design needs.
Block Diagram
The block diagram provided in the datasheet showcases the internal structure of the PWM controller, highlighting key components such as the oscillator (OSC), ramp generator, error amplifier (EAOUT), pulse width modulation latch and comparator, current and voltage sensing circuits, soft-start and fault handling logic, as well as under-voltage lockout protection (UVLO).
Important Notices
Texas Instruments includes important notices regarding product availability, standard warranty, and usage in critical applications at the end of the datasheet. It emphasizes that information is current as of the publication date, and products conform to specifications per the terms of TI’s standard warranty. Production processing may not include testing of all parameters.
Manual:
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