Conv DC-DC Single Step Down 3V to 5.5V 16-Pin QSOP

The MAX1809 is a reversible energy flow, constant-off-time, pulse-width modulated (PWM), step-down DC-DC converter. It is ideal for use in notebook and subnotebook computers that require 1.1V to 5V active termination power supplies. This device features an internal PMOS power switch and internal synchronous rectifier for high efficiency and reduced component count. The internal 90mO PMOS power switch and 70mO NMOS synchronous-rectifier switch easily deliver continuous load currents up to 3A. The MAX1809 accurately tracks an external reference voltage, produces an adjustable output from 1.1V to VIN, and achieves efficiencies as high as 93%. The MAX1809 uses a unique current-mode, constant-off-time, PWM control scheme that allows the output to source or sink current. This feature allows energy to return to the input power supply that otherwise would be wasted. The programmable constant-off-time architecture sets switching frequencies up to 1MHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1809 features an adjustable soft-start to limit surge currents during startup, a 100% duty-cycle mode for low-dropout operation, and a low-power shutdown mode that disables the power switches and reduces supply current below 1µA. The MAX1809 is available in a 28-pin QFN with an exposed backside pad, a 28-pin thin QFN, or a 16-pin QSOP.

• Source/Sink 3A
• ±1% Output Accuracy
• Up to 1MHz Switching Frequency
• 93% Efficiency
• Internal PMOS/NMOS Switches
  • 90mO/70mOOn-Resistance at V_IN = 4.5V
  • 110mO/80mO On-Resistance at V_IN = 3V

1.1V to V_IN Adjustable Output Voltage

3V to 5.5V Input Voltage Range

<1µA Shutdown Supply Current

Programmable Constant-Off-Time Operation

Thermal Shutdown

Adjustable Soft-Start Inrush Current Limiting

Output Short-Circuit Protection