600mA, 1.2MHz, Synchronous Step-Down DC-DC Converter
UM3501 SOT23-5
UM3501DA DFN6 2.0×2.0
General Description
UM3501 is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter,
capable of delivering 600mA output current over a wide input voltage range from 2.5V to 5.5V.
The target application of UM3501 is for portable electronic devices that are powered from 1-cell
Li-ion battery or from other power sources within the range such as cellular phones, PDAs and
handy-terminals. Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction
loss at PWM mode. No external schottky diode is required in practical application. The UM3501
automatically turns off the synchronous rectifier while the inductor current is low and enters
discontinuous PWM mode. This can increase efficiency at light load condition.
UM3501 enter shutdown mode and consumes less than 0.1uA when EN pin is pulled low. The
operation frequency is set to 1.2MHz. This along with small SOT23-5 package and DFN6 2.0×2.0
package provides small PCB area application. Other features include lower internal reference
voltage with 2% accuracy, over temperature protection, and over current protection.
Applications
Features
Cellular and Smart Phones
Microprocessors and DSP Core
Supplies
Wireless and DSL Modems
PDAs, GPS
MP3 Player
High Efficiency: Up to 90%
1.2MHz Constant Switching Frequency
600mA Output Current
Integrated Main Switch and Synchronous
Rectifier. No Schottky Diode Required
2.5V to 5.5V Input Voltage Range
Low Quiescent Current: 50µA
Thermal Fault Protection
Portable Instruments
<1µA Shutdown Current
Lead Free SOT23-5 Package and DFN6
2.0×2.0 Package
Typical Application Circuit
L1
2.2uH
VOUT 1.8V
VIN
VIN
EN
SW
R2
634K
C1
4.7uF
C3
10uF
UM3501
FB
GND
R1
316K
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http://www.union-ic.com Rev.06 Feb.2015 1/11