Lm2576- 52Khz Simple 3A Buck Regulator - Toshiba 27WLT56B Service Manual

LM2576- 52kHz Simple 3A Buck Regulator

12.13.
12.13.1. General Description
The LM2576 series of monolithic integrated circuits provide all the active functions for a step-down
(buck) switching regulator. Fixed versions are available with a 3.3V, 5V, or 12V
fixed output. Adjustable versions have an output voltage range from 1.23V to 37V. Both versions are
capable of driving a 3A load with excellent line and load regulation. These regulators are simple to use
because they require a minimum number of external components and include internal frequency
compensation and a fixed-frequency oscillator. The LM2576 series offers a high efficiency replacement
for popular three-terminal adjustable linear regulators. It substantially reduces the size of the heat sink,
and in many cases no heat sink is required. A standard series of inductors available from several
different manufacturers are ideal for use with the LM2576 series. This feature greatly simplifies the
design of switch-mode power supplies. The feedback voltage is guaranteed to ±2% tolerance for
adjustable versions, and the output voltage is guaranteed to ±3% for fixed versions, within specified
input voltages and output load conditions. The oscillator frequency is guaranteed to ±10%. External
shutdown is included, featuring less than 200⎧A standby current. The output switch includes cycle-
bycycle current limiting and thermal shutdown for full protection under fault conditions.
12.13.2. Features
• 3.3V, 5V, 12V, and adjustable output versions
• Voltage over specified line and load conditions:
Fixed version: ±3% max. output voltage
Adjustable version: ±2% max. feedback voltage
• Guaranteed 3A output current
• Wide input voltage range:
4V to 40V
27" TFT TV Service Manual
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05/09/2005