MAX1627

Features:

Low Dropout Voltage
100% Maximum Duty Cycle
Soft-Start Limits Start-Up Current
Efficiency >90% (3mA to 2A Loads)
Output Power >12.5W
90µA Max Quiescent Current
1µA Max Shutdown Current
Up to 300kHz Switching Frequency
16.5V Max Input Voltage
Output Voltage: 5V/3.3V (MAX1626)
                            Adjustable (MAX1627)
Current-Limited Control Scheme


Application

PCMCIA Power Supplies
Personal Digital Assistants
Hand-Held Computers
Portable Terminals
Low-Cost Notebook Computer Supplies
5V to 3.3V Green PC Applications
High-Efficiency Step-Down Regulation
Minimum-Component DC-DC Converters
Battery-Powered Applications


Pinout




Specifications

Supply Voltage, V+ to GND...................................-0.3V, +17V
OUT, FB, 3/5, SHDN, REF, CS, EXT to GND...-0.3V, (V+ + 0.3V)
Maximum Current at REF (IREF) ....................................15mA
Maximum Current at EXT (IEXT) ....................................50mA
Continuous Power Dissipation (TA = +70°C)
  SO (derate 5.88mW/°C above +70°C) ....................471mW
Operating Temperature Range
  MAX1626ESA/MAX1627ESA..........................-40°C to +85°C
Storage Temperature Range ......................-65°C to +160°C
Lead Temperature (soldering, 10sec) ........................+300°C


Description

The MAX1626/MAX1627 step-down DC-DC switching controllers provide high efficiency over loads ranging from 1mA to more than 2A. A unique current-limited, pulse-frequency-modulated (PFM) control scheme operates with up to a 100% duty cycle, resulting in very
low dropout voltages. This control scheme eliminates minimum load requirements and reduces the supply current under light loads to 90µA (versus 2mA to 10mA for common pulse-width modulation controllers).

These step-down controllers drive an external P-channel MOSFET, allowing design flexibility for applications to 12W or higher. Softstart reduces current surges during start-up. A high switching frequency (up to 300kHz) and operation in continuous-conduction mode allow the use of tiny surface-mount inductors. Output capacitor requirements are also reduced, minimizing PC board area and system costs.

The output voltage is preset at 5V or 3.3V for the MAX1626 and adjustable for the MAX1627. Input voltages can be up to 16.5V. The MAX1626/MAX1627 are functional upgrades for the MAX1649/MAX1651.