LESHAN RADIO COMPANY, LTD.
5A, 500KHz Synchronous Boost Converter
with Output Disconnect
LR8425 Series
INTRODUCTION:
FEATURES:
The /58425 devices provide a power supply
solution for products powered by either a one-cell
Li-Ion or Li-polymer, or a two to three-cell
z
z
z
97% Efficiency at VOUT=5V from 3.3V Input
Device Quiescent Current: 37μA (Typ)
Guaranteed 2.5A Output Current at VOUT=5V
from 3.3V Input
alkaline, NiCd or NiMH battery. The converter
generates a stable output voltage that is
adjusted by an external resistor divider. It
provides high efficient power conversion and is
capable of delivering output currents up to
1.5A at 5V at a supply voltage down to 2V.
The implemented boost converter is based on a
fixed switching frequency (500kHz typical),
current-mode controller using a synchronous
rectifier to obtain maximum efficiency. Boost
switch and rectifier switch are connected internally
to provide the lowest leakage inductance and best
EMI behavior possible. The current-mode control
scheme provides fast transient response and
good output voltage accuracy. At light load, the
converter will automatically enter into Pulse
Frequency Modulation (PFM) operation to reduce
the dominant switching losses. During PFM
operation, the IC consumes very low quiescent
current and maintains high efficiency over a wide
load current range.
z
z
500kHz PWM Switching Frequency
Synchronous and Embedded Power
MOSFETs, No Schottky Diode Required
Low RDS(ON) (main switch/synchronous switch)
at 5.0V output: 20/40mohm
Input Voltage Range: 1.8V to 5.25V
Adjustable Output Voltage Range:
from 2.5V to 5.5V
Pulse Frequency Modulation Operation for
Improved Efficiency at Low Output Power
Current Mode Operation with Internal
Compensation for Excellent Line and Load
Transient Response
Logic Controlled Shutdown(<1μA)
Load Disconnect During Shutdown
Automatic output discharge at shutdown:ꢀ
/58425A: Auto output discharge functionꢀ
/58425B: No output discharge function
Low Battery Comparator
z
z
z
z
z
z
z
z
z
z
z
z
z
z
z
Internal Soft-Start to Limit Inrush Current
Over Current Protection
Input Under Voltage Lockout
Output Over Voltage Protection
Over-Temperature Protection
The converter can be disabled to minimize battery
drain. During shutdown, the load is completely
disconnected from the battery.
The device allows use of small inductors and
output capacitors for USB devices.
Available in 2.1mm x 2.1mm QFN10 Package
APPLICATIONS˖˖
z
All Single Cell Li or Dual Cell Battery
Operated Products as Tablet PC, Smartbook
and Other Portable Equipment
Products including portable HDMI and USB-OTG
USB Hosts Without Native 5V Supplies
USB Charging Port (5V)
Power Bank, Battery Backup Units
Wireless Peripherals
Portable Audio Players
Personal Medical Devices
z
z
z
z
z
z
z
z
z
Industrial Metering Equipments
DC/DC Micro Modules
1/7
Ver0.5