Dual, 2-Phase Step-Down Switching Controller

The LT3742 is a dual step-down DC/DC switching regulator controller that drives high side N-channel power MOSFETs. A 500kHz fixed frequency current mode architecture provides fast transient response with simple loop compensation components and cycle-by-cycle current limiting. The output stages of the two controllers operate 180° out of phase to reduce the input ripple current, minimizing the noise induced on the input supply, and allowing less input capacitance.

An internal boost regulator generates a bias rail of VIN + 7V to provide gate drive for the N-channel MOSFETs allowing low dropout and 100% duty cycle operation. The LT3742 can be used for applications where both controllers need to operate independently, or where both controllers are used to provide a single higher current output.

The device is available in a thermally enhanced 4mm × 4mm QFN package.

Applications

* Satellite and Cable TV Set-Top Boxes

* Distributed Power Regulation

* Automotive Systems

* Super Capacitor Charger

* Wide Input Voltage Range: 4V to 30V

* Wide Output Voltage Range: 0.8V to VIN

* Low Shutdown IQ: 20μA

* Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise

* 0.8V ±1.5% Voltage Reference

* 500kHz Current Mode Fixed Frequency Operation

* Internal Boost Converter Provides Bias Rail for N-Channel MOSFET Gate Drive

* Power Good Voltage Monitor for Each Output

* Programmable Soft-Start

* 24-Lead 4mm × 4mm × 0.75mm Package