Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

LR645LG-G Datasheet(PDF) 4 Page - Supertex, Inc

Part # LR645LG-G
Description  High Input Voltage SMPS Start-up / Linear Regulator
Download  9 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  SUTEX [Supertex, Inc]
Direct Link  http://www.supertex.com
Logo SUTEX - Supertex, Inc

LR645LG-G Datasheet(HTML) 4 Page - Supertex, Inc

  LR645LG-G Datasheet HTML 1Page - Supertex, Inc LR645LG-G Datasheet HTML 2Page - Supertex, Inc LR645LG-G Datasheet HTML 3Page - Supertex, Inc LR645LG-G Datasheet HTML 4Page - Supertex, Inc LR645LG-G Datasheet HTML 5Page - Supertex, Inc LR645LG-G Datasheet HTML 6Page - Supertex, Inc LR645LG-G Datasheet HTML 7Page - Supertex, Inc LR645LG-G Datasheet HTML 8Page - Supertex, Inc LR645LG-G Datasheet HTML 9Page - Supertex, Inc  
Zoom Inzoom in Zoom Outzoom out
 4 / 9 page
background image
4
LR645
Figure 2: High Current SMPS Start-Up Circuit
R2
R1
+
15V
to
400V
+
5.0V
DN2540
C
OUT
C
IN
V
CC
V
AUX = 12V
Note: When used with the DN25, +V
IN is not connected on the LR6.
PWM IC
LR645
V
OUT
GND
GATE
TRIM
LR645: High Current SMPS Start-Up Circuit
The 8 lead version of the LR645 has connections for an ex-
ternal depletion-mode MOSFET for higher output current and
external resistors for adjustable output voltage. As shown in
Figure 2, the output current is increased to 150mA by using
the Supertex 400V depletion-mode MOSFET DN2540. The
maximum operating input voltage will be limited by the drain-
to-source breakdown voltage of the external MOSFET, but
cannot exceed the 450V rating of the LR645.
The output voltage can be adjusted from 8V to 12V with 2ex-
ternal resistors, R1 and R2. The ratio of R2/R1 determines
the output voltage. R2 is connected between the V
OUT and
TRIM pins. R1 is connected between TRIM and GND pins.
Figure 5 is a curve showing output voltage versus resistor
ratio R2/R1. The optimum range for R1 + R2 is 200KΩ to
300KΩ. This minimizes loading and optimizes accuracy of
the output voltage. Figure 5 uses an R1 + R2 of 250KΩ.
LR645: Off Line Linear Regulator
Circuits requiring low voltages to operate logic and analog
circuits benefit from the LR645. The conventional use of
step down transformers can be eliminated, thereby saving
space and cost. Some examples of these applications are:
proximity controlled light switches, street lamp controls, and
low voltage power supplies for appliances such as washing
machines, dishwashers, and refrigerators.
The wide operating input voltage range of 15V to 450V as
well as the ripple rejection ratio of 50dB minimum allows the
use of a small, high voltage input capacitor. The input AC
line can be either full-wave or half-wave rectified. A minimum
output capacitance of 0.01µF is recommended for output
stability.
Figure 3 shows the LR645 as a pre-regulator to a precision-
regulator for high precision regulation. Higher output cur-
rent is also possible by using an external depletion-mode
MOSFET DN2540N5 as shown in Figure 4.
Power Dissipation Considerations
The LR645 is a true linear regulator. Its power dissipation is-
therefore a function of input voltage and output load current.
Forexample, if the LR645 is providing a continuous load cur-
rent of 3mAat 10V while its input voltage is 400V, total dis-
sipation in the LR645 will be:
P
DISS= (VIN - VOUT) x (IOUT + IMAX QUIESCENT)
= (400V - 10V) x (3.0mA + 150µA)
= 1.23 Watts
The 1.23 watts is for continuous operation. This is within the
dissipation capabilities of the TO-220 and SOT-89 packag-
es. See the thermal characteristics chart on page 2 for derat-
ings. For SMPS start-up applications, the output current is
usually required only during start-up. This duration depends
upon the auxiliary supply output capacitor and C
OUT, but is
typically a few hundred milliseconds. All package types of
the LR645 have been characterized for use with a C
OUT of at
least 10µF, and an AC line of 277V.
5.000V
± 0.002V
@
0 to 3mA
AC Line
24V
to
277V
C
OUT
0.1µF
C
IN
1.0µF
LR6
Max
875
ACSA
Figure 3: Cascading for Precision


Similar Part No. - LR645LG-G

ManufacturerPart #DatasheetDescription
logo
Supertex, Inc
LR645LG SUTEX-LR645LG Datasheet
322Kb / 4P
   High Input Voltage SMPS Start-up / Linear Regulator
More results

Similar Description - LR645LG-G

ManufacturerPart #DatasheetDescription
logo
Supertex, Inc
LR645 SUTEX-LR645 Datasheet
322Kb / 4P
   High Input Voltage SMPS Start-up / Linear Regulator
logo
Microchip Technology
LR745 MICROCHIP-LR745 Datasheet
333Kb / 15P
   High-Input Voltage SMPS Start-up
01/27/15
logo
Supertex, Inc
LR745N8-G SUTEX-LR745N8-G Datasheet
558Kb / 7P
   High Input Voltage SMPS Start-up
LR745N3-G SUTEX-LR745N3-G Datasheet
558Kb / 7P
   High Input Voltage SMPS Start-up
LR745 SUTEX-LR745 Datasheet
327Kb / 5P
   High Input Voltage SMPS Start-up Circuit
logo
Lowpower Semiconductor ...
LP6205S POWER-LP6205S Datasheet
364Kb / 5P
   1.3V Start-up Input Voltage
logo
List of Unclassifed Man...
TS31023 ETC2-TS31023 Datasheet
1Mb / 16P
   High Input Voltage Linear Regulator
TS31223 ETC2-TS31223 Datasheet
1Mb / 16P
   High Input Voltage Linear Regulator
logo
Semtech Corporation
TS31023 SEMTECH-TS31023 Datasheet
2Mb / 15P
   High Input Voltage Linear Regulator
logo
Infineon Technologies A...
IRS25751LPBF INFINEON-IRS25751LPBF Datasheet
610Kb / 13P
   High-Voltage Start-Up IC
January 15, 2015
More results


Html Pages

1 2 3 4 5 6 7 8 9


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.NET
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com