Features

• Ultra-High Efficiency: Over 95% Possible
• Current-Mode Operation for Excellent Line and Load Transient Response
• High Efficiency Maintained Over Three Decades of Output Current
• Low 160µA Standby Current at Light Loads
• Logic Controlled Micropower Shutdown: I_Q <20µA
• Wide V_IN Range: 3.5V* to 20V
• Short-Circuit Protection
• Very Low Dropout Operation: 100% Duty Cycle
• Synchronous FET Switching for High Efficiency
• Adaptive Nonoverlap Gate Drives
• Output Can Be Externally Held High in Shutdown
• Available in 14-Pin Narrow SO Package

Typical Application

Description

The LTC1148 series is a family of synchronous stepdown switching regulator controllers featuring automatic Burst Mode™ operation to maintain high efficiencies at low output currents. These devices drive 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 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 by only the R_DS(ON) of the external MOSFET and resistance of the inductor and current sense resistor.

The LTC1148 series combines synchronous switching for maximum efficiency at high currents with an automatic low current operating mode, called Burst Mode operation, which reduces switching losses. Standby power is reduced to only 2mW at V_IN = 10V (at I_OUT = 0). Load currents in Burst Mode operation are typically 0mA to 300mA.

For operation up to 48V input, see the LTC1149 and LTC1159 data sheets and Application Note 54.

* LTC1148L and LTC1148L-3.3 only.
Protected by U.S. Patents, including 6580258, 5481178.