High Power Step-Down Switching Regulator Controller

The LTC1430A is a high power, high efficiency switching regulator controller optimized for 5V to 1.xV-3.xV applications. It includes a precision internal reference and an internal feedback system that can provide output regulation of ±1% over temperature, load current and line voltage shifts. The LTC1430A uses a synchronous switching architecture with two N-channel output devices, eliminating the need for a high power, high cost P-channel device. Additionally, it senses output current across the drain-source resistance of the upper N-channel FET, providing an adjustable current limit without an external low value sense resistor.

The LTC1430A includes a fixed frequency PWM oscillator for low output ripple under virtually all operating conditions. The 200kHz free-running clock frequency can be externally adjusted from 100kHz to above 500kHz. The LTC1430A’s maximum duty cycle is typically 93.5% compared to 88% for the LTC1430. This permits 3.3V to 2.xV conversion using a low power 5V supply. The LTC1430A features low 350µA quiescent current, allowing greater than 90% efficiency operation in converter designs from 1A to greater than 50A output current. Shutdown mode drops the LTC1430A supply current to 1µA.

For new designs, refer to the LTC3830.

Applications

* Power Supply for Pentium® II and AMD-K6® Microprocessors

* High Power 5V to 3.xV Regulators

* Local Regulation for Dual Voltage Logic Boards

* Low Voltage, High Current Battery Regulation

* High Power 5V to 1.xV-3.xV Switching Controller: Can Exceed 10A Output

* Maximum Duty Cycle > 90% Permits 3.3V to 2.xV Conversion Using a Low Power 5V Supply

* All N-Channel External MOSFETs

* Fixed Frequency Operation—Small L

* Excellent Output Regulation: ±1% Over Line, Load and Temperature Variations

* High Efficiency: Over 95% Possible

* No Low Value Sense Resistor Needed

* Outputs Can Drive External FETs with Up to 10,000pF Gate Capacitance

* Quiescent Current: 350µA Typ, 1µA in Shutdown

* Fast Transient Response

* Adjustable or Fixed 3.3V Output

* Available in 8-Lead SO and 16-Lead GN and SO Packages