HITACHI 17LD4220U
Manual de Servicio

11.2. LM2576 11.2.1. General Description The LM2576 series of regulators are monolithic integrated circuits ideally suited for easy and convenient design of a step�down switching regulator (buck converter). All circuits of this series are capable of driving a 3.0 A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5.0 V, 12 V, 15 V, and an adjustable output version. These regulators were designed to minimize the number of external components to simplify the power supply design. Standard series of inductors optimized for use with the LM2576 are offered by several different inductor manufacturers. Since the LM2576 converter is a switch�mode power supply, its efficiency is significantly higher in comparison with popular three�terminal linear regulators, especially with higher input voltages. In many cases, the power dissipated is so low that no heatsink is required or its size could be reduced dramatically. A standard series of inductors optimized for use with the LM2576 are available from several different manufacturers. This feature greatly simplifies the design of switch�mode power supplies. The LM2576 features include a guaranteed ±4% tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency (±2% over 0°C to 125°C). External shutdown is included, featuring 80 mA (typical) standby current. The output switch includes cycle�by�cycle current limiting, as well as thermal shutdown for full protection under fault conditions.

11.2.2. Features � 3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions � Adjustable Version Output Voltage Range, 1.23 to 37 V ±4% Maximum Over Line and Load Conditions � Guaranteed 3.0 A Output Current � Wide Input Voltage Range � Requires Only 4 External Components � 52 kHz Fixed Frequency Internal Oscillator � TTL Shutdown Capability, Low Power Standby Mode � High Efficiency � Uses Readily Available Standard Inductors � Thermal Shutdown and Current Limit Protection � Moisture Sensitivity Level (MSL) Equals 1

11.2.3. Pin description

5 17� TFT TV Service Manual 21/09/2004