MAX1653

19-1357; Rev 1; 7/98 KIT ATION EVALU E L B AVAILA High-Efficiency, PWM, Step-Down DC-DC Controllers in 16-Pin QSOP General Description ____________________________Features o 96% Efficiency o Small, 16-Pin QSOP Package (half the size of a 16-pin narrow SO) o Pin-Compatible with MAX797 (MAX1653/MAX1655) o Output Voltage Down to 1V (MAX1655) o 4.5V to 30V Input Range o 99% Duty Cycle for Lower Dropout o 170µA Quiescent Supply Current o 3µA Logic-Controlled Shutdown o Dual, N-Channel, Synchronous-Rectified Control o Fixed 150kHz/300kHz PWM Switching, or Synchronized from 190kHz to 340kHz o Programmable Soft Start o Low-Cost Secondary Outputs (MAX1652/MAX1654) MAX1652–MAX1655 The MAX1652–MAX1655 are high-efficiency, pulsewidth-modulated (PWM), step-down DC-DC controllers in small QSOP packages. The MAX1653/MAX1655 also come in 16-pin narrow SO packages that are pincompatible upgrades to the popular MAX797. Improvements include higher duty-cycle operation for better dropout, lower quiescent supply currents for better light-load efficiency, and an output voltage down to 1V (MAX1655). The MAX1652–MAX1655 achieve up to 96% efficiency and deliver up to 10A using a unique Idle Mode™ synchronous-rectified PWM control scheme. These devices automatically switch between PWM operation at heavy loads and pulse-frequency-modulated (PFM) operation at light loads to optimize efficiency over the entire output current range. The MAX1653/MAX1655 also feature logic-controlled, forced PWM operati...