High-Speed PWM Controller – Texas Instruments

Category: Electronics, Other Semiconductors, Texas Instruments HighPerformance Analog

Overview

The datasheet presents a range of high-speed PWM controllers from Texas Instruments, specifically the UC1823A, UC2823A, UC2823B, UC3823A, UC3823B, UC1825A, UC2825A, UC2825B, UC3825A, and UC3825B models, which deliver enhanced performance compared to the standard UC3823 and UC3825 family.

Features

Key features include:

Compatibility with both voltage-mode and current-mode control methods.
Operation at switching frequencies up to MHz, with 50-ns propagation delay to output.
High-current dual totem pole outputs, capable of 2-A peak.
Trimmed oscillator discharge current and a low startup current of 100 LA.
Current limiting and overcurrent protection with full cycle restart.

Enhancements

Enhancements over previous versions include:

Error amplifier with a gain bandwidth product of 12 MHz and input offset voltage of 2 mV.
Current limit threshold with a tighter tolerance of 5%.
Oscillator discharge current is specified for accurate dead time control and frequency accuracy improved to 6%.
Redesigned output drivers actively sink current during undervoltage lockout.

Block Diagram Analysis

The block diagram outlines the internal circuitry, revealing an oscillator (OSC), clock/flip-flop (CLK/FF), PWM latch and comparator, soft-start and current limit circuits, overcurrent protection, a fault latch with undervoltage lockout (UVLO), and an internal bias system. Outputs include OUTA and OUTB for PWM signaling. Additionally, there is a 5.1V reference voltage (VREF) output alongside restart delay and soft-start complete latch circuits.

The UC1823A version specifically indicates that toggles Q and Q-bar are constantly low, suggesting certain functional limitations or predefined states within this model. The diagram also emphasizes the UC2823B and UC3823B variants with a 16V UVLO start threshold, contrasting the UC2823A and UC3823A models beginning at a 9.2V/8.4V threshold.

Product Information and Copyright Notice

Both the availability notice and the standard warranty disclaimer are mentioned, highlighting that while information is current as of the publication date, production processing does not include testing all parameters. This is a customary notice to signify that individual results may vary, and chips are assured only per Texas Instruments’ standard warranty terms.