100kHz, 1.25A Switching Regulator with Catch Diode

The LT1572 is a 1.25A 100kHz monolithic switching regulator with on-board switch and catch diode included in one package. It combines an LT1172 with a 1A Schottky catch diode. The LT1572 can be operated in all standard switching configurations, including boost, buck, SEPIC, flyback, forward, inverting and "Cuk". All necessary control, oscillator and protection circuitry is included on the die with the high efficiency switch. This makes the part extremely easy to use and provides "bustproof" operation similar to that obtained with 3-pin linear regulators.

The LT1572 operates with supply voltages from 3V to 30V and draws only 6mA quiescent current. It can deliver load power up to 15W with no external power devices. By utilizing a current mode switching technique, the LT1572 achieves excellent response to load and line transients.

The LT1572 has many unique features not found on the more difficult to use control chips presently available. It uses adaptive anti-sat switch drive to allow very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 50µA typical for standby operation. External synchronizing of switching frequency is possible, with a range of 120kHz to 160kHz.

Applications

* 3.3V-to-5V and 5V-to-12V Boost Converters

* Negative-to-Positive Converter

* SEPIC Converter (Input Can Be Greater or Less Than Output)

* Battery Charger

* Catch Diode Included in Package

* Wide Input Voltage Range: 3V to 30V

* Low Quiescent Current: 6mA

* Internal 1.25A Switch

* Very Few External Parts Required

* Self-Protected Against Overloads

* Operates in Nearly All Switching Topologies

* Shutdown Mode Draws Only 50µA Typical Current

* Can Be Externally Synchronized