Conv DC-DC Single Step Down 3V to 5.5V 16-Pin SSOP T/R

The MAX1644 constant-off-time, PWM step-down DC-DC converter is ideal for use in applications such as PC cards, CPU daughter cards, and desktop computer bus-termination boards. The device features internal synchronous rectification for high efficiency and reduced component count. It requires no external Schottky diode. The internal 0.10O PMOS power switch and 0.10O NMOS synchronous-rectifier switch easily deliver continuous load currents up to 2A. The MAX1644 produces a preset +3.3V or +2.5V output voltage or an adjustable output from +1.1V to VIN. It achieves efficiencies as high as 95%. The MAX1644 uses a unique current-mode, constant-off-time, PWM control scheme, which includes an Idle Mode to maintain high efficiency during light-load operation. The programmable constant-off-time architecture sets switching frequencies up to 350kHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The device also features an adjustable soft-start to limit surge currents during start-up, a 100% duty cycle mode for low-dropout operation, and a low-power shutdown mode that disconnects the input from the output and reduces supply current below 1µA. The MAX1644 is available in a 16-pin SSOP package.

• ±1% Output Accuracy
• 95% Efficiency
• Internal PMOS and NMOS Switches
  • 70mO On-Resistance at V_IN = +4.5V
  • 100mO On-Resistance at V_IN = +3V

Output Voltage

• +3.3V or +2.5V Pin-Selectable
• +1.1V to V_IN Adjustable

+3V to +5.5V Input Voltage Range

360µA (max) Operating Supply Current

< 1µA Shutdown Supply Current

Programmable Constant-Off-Time Operation

350kHz (max) Switching Frequency

Idle Mode Operation at Light Loads

Thermal Shutdown

Adjustable Soft-Start Inrush Current Limiting

100% Duty Cycle During Low-Dropout Operation

Output Short-Circuit Protection

16-Pin SSOP Package