19-1618; Rev 0; 4/00
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
The MAX1730 regulated step-down charge pump gen-
erates up to 50mA at fixed output voltages of 1.8V or
1.9V from an input voltage in the 2.7V to 5.5V range.
Specifically designed to provide high-efficiency logic
supplies in applications that demand a compact
design, the MAX1730 employs fractional conversion
techniques to provide efficiency exceeding that of a lin-
The MAX1730 operates at up to 2MHz, permitting the
use of small 0.22µF flying capacitors while maintaining
low 75µA quiescent supply current. Proprietary soft-
start circuitry prevents excessive current from being
drawn from the supply during startup, making the
MAX1730 compatible with higher impedance sources
such as alkaline and lithium-ion cells.
The MAX1730 is available in a space-saving 10-pin
µMAX package that is only 1.09mm high and occupies
one-half the area of an 8-pin SO.
Low-Voltage Logic Supplies
o > 85% Peak Efficiency
o 50mA Guaranteed Output Current
o Dual-Mode 1.8V or 1.9V Output
o ±3% Output Voltage Accuracy
o Up to 2MHz Operating Frequency
o Small 0.22µF Capacitors
o No Inductor Required
o 2.7V to 5.5V Input Voltage Range
o Output Disconnects from Input in Shutdown Mode
o Small 10-Pin µMAX Package (1.09mm max height)
-40°C to +85°C
Typical Operating Circuit
2.7V TO 5.5V
SHDN IN OUT
FB GND PGND
1.8V OR 1.9V, UP TO 50mA
________________________________________________________________ Maxim Integrated Products 1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.