L5991/L5991A Primary Controller with Standby Datasheet

Category: Electronics, Other Semiconductors, STMicroelectronics Inc

Overview

The L5991 and L5991A are integrated primary controllers designed for primary side control in switch-mode power supplies. The controllers are tailored for fixed frequency current mode control applications, featuring capabilities essential for efficient power management and protection in power supply systems.

Key Features

The datasheet outlines the distinct features of the primary controller which include:

High switching frequency: Capable of PWM (Pulse Width Modulation) switching frequencies up to 1MHz, enabling designs with better power efficiency and smaller components.
Low start-up current: Less than 120µA, reducing power consumption during initial power up.
High-current output drive: Suitable for driving power MOSFETs with 1A drive capability, thus supporting applications requiring high power output.
Fully latched PWM: Logic includes double pulse suppression, enhancing stability and reliability of the PWM signal.
Variable duty cycle: Programmable up to a maximum of 100% for flexibility in controlling power output.
Standby functionality: Reduces oscillator frequency under light-load conditions, optimizing power efficiency.
Programmable soft start: Limits inrush current during startup, preventing damage to components and improving system reliability.
Integrated protection: Features primary overcurrent fault detection with a re-start delay and pulse by pulse current limit for component safety.
Under-Voltage Lockout (UVLO): With hysteresis, ensuring the controller operates within safe voltage levels.
Synchronization capability: Through IN/OUT pins, enabling coordination with external systems or multiple controllers.
Latched Disable: For overvoltage protection and power management through an external disable signal.
Current sense leading edge blanking: A 100ns built-in leading-edge blanking to prevent false triggering of the current sense.

Applications and Technology

The primary controller is ideally suited for offline or DC-DC power supply applications where precise regulation and power efficiency are required. Developed using MULTIPOWER BCD Technology, the controllers leverage a process that combines bipolar, CMOS, and DMOS technologies, allowing for integrated power and control circuitry to be fabricated on the same chip.

Available Packages and Ordering Information

The L5991 and L5991A controllers are available in two package types:

DIP16 Package
SO16 Package

Ordering numbers are as follows:

For DIP16 package: L5991/L5991A
For SO16 package: L5991D/L5991AD

Functional Diagram

The provided block diagram showcases the internal functional blocks of the controller, illustrating connections for various inputs and outputs such as VCC, VREF, PWM UVLO, Synchronization (SYNC), Over Current Protection, Soft-Start, and Stand-By among others, signifying the comprehensive features integrated within the controller for sophisticated power management.

Document Revision: September 2000 (indicated at the bottom of the first page, 1/23).