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MAX1649, MAX1651 5V/3.3V或可调、高效

2009-03-23 00:00:00

MAX1649, MAX1651 5V/3.3V或可调、高效率、低压差、降压型DC-DC控制器

The MAX1649/MAX1651 BiCMOS, step-down, DC-DC switching controllers provide high efficiency over loads ranging from 1mA to more than 2.5A. A unique, current-limited pulse-frequency-modulated (PFM) control scheme gives these devices the benefits of pulse-width-modulation (PWM) converters (high efficiency at heavy loads), while using only 100µA of supply current (vs. 2mA to 10mA for PWM converters). Dropout performance down to 300mV is provided by a high switch duty cycle (96.5%) and a low current-sense threshold (110mV).

A high switching frequency (up to 300kHz) allows these devices to use miniature external components.

The MAX1649/MAX1651 have dropout voltages less than 0.3V at 500mA and accept input voltages up to 16V. Output voltages are preset at 5V (MAX1649), or 3.3V (MAX1651). They can also be adjusted to any voltage from 1.5V to the input voltage by using two resistors.

These step-down controllers drive external P-channel MOSFETs at loads greater than 12.5W. If less power is required, use the MAX639/MAX640/MAX653 step-down converters with on-chip FETs, which allow up to a 225mA load current.

More than 90% Efficiency (10mA to 1.5A Loads)

More than 12.5W Output Power

Less than 0.3V Dropout Voltage at 500mA

100µA Max Quiescent Supply Current

5µA Max Shutdown Supply Current

16V Max Input Voltage

5V (MAX1649), 3.3V (MAX1651), or Adjustable Output Voltage

Current-Limited Control Scheme

Up to 300kHz Switching Frequency

Up to 96.5% Duty Cycle

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