LR745N3-G Datasheet, PDF (1/7 Pages) Supertex, Inc – High Input Voltage SMPS Start-up

LR745
High Input Voltage SMPS Start-up
Features
► Accepts inputs from 35V to 450V
► Output current limiting
► For PWM ICs with start-up threshold voltage of
13.9 - 18.0V
► Very low power consumption after start-up
Applications
► Notebook and laptop computers
► Telecommunication power supplies
► Battery chargers
► Motor controllers
General Description
The Supertex LR745 is a high input voltage SMPS start-
up circuit. The LR745 is ideally suited for use with industry
standard low voltage PWM ICs having start thresholds of 13.9
- 18.0V. It allows the PWM ICs to be operated from rectified
120 or 240VAC lines, and eliminates the use of power resistors
often used for this purpose.
The internal circuitry of the LR745 allows the PWM ICs to
operate at a V_CC voltage below their start threshold voltage
after start-up. The auxiliary voltage can be less than the
start threshold voltage, which allows for improved efficiency.
Current from the high voltage line is drawn only during the
start-up period. After start-up, the internal high voltage line is
disconnected from the IC, thereby reducing the continuous
power dissipation to a minimum.
Ordering Information
Device
Package Options
TO-92
TO-243AA (SOT-89)
LR745
LR745N3-G
LR745N8-G
-G indicates package is RoHS compliant (‘Green’)
Pin Configurations
VOUT
VIN
GND
TO-92 (N3)
GND
VOUT
GND
VIN
TO-243AA (SOT-89) (N8)
Package Markings
Absolute Maximum Ratings
Parameter
Value
Input voltage
450V
Output voltage
25V
Operating and storage temperature -55°C to +150^OC
Soldering temperature*
300^OC
Absolute Maximum Ratings are those values beyond which damage to the device
may occur. Functional operation under these conditions is not implied. Continuous
operation of the device at the absolute rating level may affect device reliability. All
voltages are referenced to device ground.
* Distance of 1.6mm from case for 10 seconds.
SiLR
745
YWLL
Y = Last Digit of Year Sealed
W = Code for Week Sealed
L = Lot Number
= “Green” Packaging
Package may or may not include the following marks: Si or
TO-92 (N3)
LR7W
W = Code for Week Sealed
= “Green” Packaging
Package may or may not include the following marks: Si or
TO-243AA (SOT-89) (N8)
● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: [phone] ● www.supertex.com