Features

• Dual Outputs: 3.3V and 5V or User Programmable
• Ultra-High Efficiency: Over 95% Possible
• Current Mode Operation for Excellent Line and Load Transient Response
• High Efficiency Maintained over 3 Decades of Output Current
• Low Standby Current at Light Loads: 160µA/Output
• Independent Micropower Shutdown: I_Q < 40µA
• Wide V_IN Range: 3.5V to 20V
• Very Low Dropout Operation: 100% Duty Cycle
• Synchronous FET Switching for High Efficiency
• Available in Standard 28-Pin SSOP

Typical Application

Description

The LTC1142/LTC1142L/LTC1142HV are dual synchronous step-down switching regulator controllers featuring automatic Burst Mode™ operation to maintain high efficiencies at low output currents. The devices are composed of two separate regulator blocks, each driving a pair of external complementary power MOSFETs, at switching frequencies up to 250kHz, using a constant off-time current mode architecture providing constant ripple current in the inductor. The operating current level for both regulators is user programmable via an external current sense resistor. Wide input supply range allows operation from 3.5V* to 18V (20V maximum). Constant off-time architecture provides low dropout regulation limited only by the R_DS(ON) of the external MOSFET and resistance of the inductor and current sense resistor. The LTC1142 series is ideal for applications requiring dual output voltages with high conversion efficiencies over a wide load current range in a small amount of board space.