MAX1655

96% Efficiency
Small, 16-Pin QSOP Package (half the size of a 16-pin narrow SO)
Pin-Compatible with MAX797 (MAX1653/MAX1655)
Output Voltage Down to 1V (MAX1655)
4.5V to 30V Input Range
99% Duty Cycle for Lower Dropout
170A Quiescent Supply Current
3A Logic-Controlled Shutdown
Dual, N-Channel, Synchronous-Rectified Control
Fixed 150kHz/300kHz PWM Switching, or Synchronized from 190kHz to 340kHz
Programmable Soft Start
Low-Cost Secondary Outputs (MAX1652/MAX1654)

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V+ to GND .............................................................................-0.3V to +36V
GND to PGND .......................................................................-0.3V to +0.3V
VL to GND ...............................................................................-0.3V to +6V
BST to GND............................................................................-0.3V to +36V
DH to LX ....................................................................-0.3V to (BST + 0.3V)
LX to BST.................................................................................-6V to +0.3V
SHDN to GND................................................................-0.3V to (V+ + 0.3V)
SYNC, SS, REF, SECFB, SKIP, FB to GND........................-0.3V to (VL + 0.3V)
DL to PGND ..................................................................-0.3V to (VL + 0.3V)
CSH, CSL to GND .....................................................................-0.3V to +6V
VL Short Circuit to GND...............................................................Momentary

REF Short Circuit to GND ............................................................Continuous
VL Output Current ...............................................................+50mA to -1mA
REF Output Current................................................................+5mA to -1mA
Continuous Power Dissipation (TA = +70°C)
SO (derate 8.70mW/°C above +70°C) ...........................................696mW
QSOP (derate 8.3mW/°C above +70°C) .........................................667mW
Operating Temperature Range
MAX165_E_E ......................................................................-40°C to +85°C
Storage Temperature Range ............................................-65°C to +160°C
Lead Temperature (soldering, 10sec) ...............................................+300°C

The MAX1652MAX1655 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 pgrades 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 MAX1652MAX1655 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 operation for noise-sensitive applications.

All devices operate with a selectable 150kHz/300kHz switching frequency, which can also be synchronized to an external clock signal. Both external power switches are inexpensive N channel MOSFETs, which provide low resistance while saving space and reducing cost.

The MAX1652 and MAX1654 have an additional feedback pin that permits regulation of a low-cost second output tapped from a transformer winding. The MAX1652 provides an additional positive output. The MAX1654 provides an additional negative output.

The MAX1652MAX1655 have a 4.5V to 30V input voltage range. The MAX1652/MAX1653/MAX1654's output range is 2.5V to 5.5V while the MAX1655's output range extends down to 1V. An evaluation kit (MAX1653EVKIT) is available to speed designs.