UM3502QA Datasheet, PDF (1/13 Pages) Union Semiconductor, Inc. – Low-Profile, 600mA, Synchronous Step-Down Converter with Integrated Inductor

UM3502QA
Low-Profile, 600mA, Synchronous Step-Down Converter
with Integrated Inductor
UM3502QA QFN24 4.0×4.0
General Description
The UM3502QA is a complete power conversion solution requiring only two low cost ceramic
MLCC caps. Inductor, MOSFETs, synchronous rectifier and control IC are integrated into a tiny
4mm×4mm×1.05mm QFN package. The UM3502QA is engineered to simplify design and to
minimize layout constraints. It is an ideal choice to be used to replace less efficient LDO to
achieve improved efficiency in space restricted applications. The UM3502QA is capable of
delivering 600mA output current over a wide input voltage range from 2.5V to 5.5V.
The UM3502QA is a high-efficiency, step-down DC-DC converter with a constant PWM
frequency, current mode architecture. The UM3502QA automatically turns off the synchronous
rectifier while the inductor current is low, and enters pulse skipping mode at light load condition.
This can increase efficiency. The operation frequency is set to 1.2MHz at normal load condition.
The UM3502QA enters shutdown mode and consumes less than 0.1µA when EN pin is pulled
low.
Applications
Features
 Cellular and Smart Phones
 MCU, DSP and FPGA Core Supplies
 Wireless and DSL Modems
 Portable Game Consoles and
Instruments
 PDAs, GPS
 Bluetooth Headsets
 Battery-Powered Devices
 Ultra Small QFN Package 4.0×4.0×1.05
 Integrated Inductor
 No Schottky Diode Required
 High Efficiency: Up to 90%
 600mA Output Current
 0.6V Minimum Output Voltage
 2.5V to 5.5V Input Voltage Range
 <1µA Shutdown Current
 Pulse Skipping Mode Operation
 Thermal Fault Protection
Typical Application Circuit
VIN 2.5V to 5.5V
PV_IN
V_OUT
AV_IN
UM3502QA
CIN
4.7µF
EN
FB
(CA)* ^{AGND PGND}
(CFF)* ^R2
634K
VOUT
1.8V
R1
316K
COUT
10µF
* C_A and C_FF are optional.
Light Load Efficiency
Light Load Efficiency vs. Input Voltage
100
90
80
70
60
50
40
30
20
IL^IOLOAADD⁼=0⁰.^.5⁵m^mA^A
IL^IO^LOA^AD^D==0⁰.^.8⁸m^mA^A
10
IL^IO^LOA^AD^D==1¹.^.0⁰m^mA^A
VOUT=1.8V
0
2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
Input Voltage (V)
________________________________________________________________________
http://www.union-ic.com Rev.01 Nov.2015
1/13