They use a proprietary current-limited control scheme that operates at up to a 100% duty cycle to ensure lowest possible dropout while maintaining a low 50 microamps quiescent supply current. An internal synchronous rectifier eliminates the cost and size of an external diode and improves efficiency, especially at low output voltages; 3.6 V input to 3.3 V output is 97% efficient at 50 mA and 87% at 1 mA.Only three small external components are needed for a complete DC-DC solution.
The input voltage range is 2 V to 5.5 V. The output has 1.5% tolerance. The MAX1921 output is preset with internal resistors at popular voltages of 1.5 V, 1.8 V, 2.5 V, 3 V, and 3.3 V. The MAX1920 output is adjustable from 1.25 V to 5 V using an external resistor-divider. Built-in soft-start limits startup currents.
The MAX1920/MAX1921 are available in space-saving 6-pin SOT23 packages screened for the extended-industrial temperature range ( 40°C to 85°C).