Electronica

LR645 High Input Voltage SMPS Start-up / Linear Regulator
Ordering Information
Order Number / Package Max. Input Voltage 450V TO-92 LR645N3 TO-243AA* LR645N8 TO-220 SO-8 Die Product marking for TO-243AA: LR6❋ where ❋ = 2-week alpha date code

LR645N5 LR645LG LR645ND

*Same as SOT-89. Product supplied on 2000 piece carrier tape reels.

Features
❏ Accepts inputs from 15V to 450V ❏Compatible with industry standard PWM ICs. See application note AN-H28. ❏ Output currents up to 3mA continuous, 30mA peak ❏ Supply current typically 50µA ❏ Line regulation typically 0.1mV/V ❏ Output can be trimmed from 8.0V to 12V ❏ Output current can be increased to 150mA with external FET

General Description
The Supertex LR6 is a high input voltage, low output current linear regulator. It has a3-terminal fixed output voltage version available in TO-92, TO-220 and SOT-89 packages as well as an adjustable voltage version available in 8 pin SOIC package. The 3-terminal version functions like any other low voltage 3-terminal regulator except it allows the use of much higher input voltages. When used in a SMPS start-up circuit, it eliminates the need for large power resistors. In thisapplication, current is drawn from the high voltage line only during start-up. Only leakage current flows after start-up thereby reducing the continuous power dissipation to a few milliwatts. The adjustable voltage version allows trimming of the output voltage from 8V to 12V. This version can also be connected to an external depletion mode MOSFET for increased output current. When used in conjunction withSupertex depletion mode MOSFET DN2540N5, up to a 150mA is achieved.

Applications
❏ Off-line SMPS startup circuits (pulse loads) ❏ Low power off-line regulators ❏ Regulators for noisy inputs

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Caution
The LR6 does NOT provide galvanic isolation. When operated from an AC line, potentially lethal voltages can be present on the IC. Adequate means of protecting the enduser from such voltages must be provided by the circuit developer.

Pin Configuration
TAB
1 2 3

TAB

TO-243AA (SOT-89)

123

Absolute Maximum Ratings
Input Voltage Output Voltage Operating and Storage Temperature Soldering Temperature*
*Distance of 1.6mm from case for 10 seconds

TO-92
450V 15.5V
5 1 2 3 4 1 2 3

SO-8 +VIN TO-92 TO-243AA 1 1 1 1 GND 2 2, TAB 2, TAB 3 VOUT 3 33 4 Trim — — — 5

TO-220
Gate — — — 7

–55°C to +150°C 300°C

For detailed circuit and application information, please refer to application note AN-H28.
11/12/01

TO-220 P-DIP

Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liabilityindemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to theSupertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.

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LR645

Thermal Characteristics
Package SO-8 TO-92 TO-220 TO-243AA
†

Block Diagram
θ ja °C/W 400† 170 70 78
†

Power Dissipation @ TA = 25°C 0.31W 0.74W 1.8W 1.6W

θ jc °C/W 156 125 8.3 15VIN

VOUT

Mounted on FR5 board, 25mm x 25mm x 1.57mm. Significant PD increase possible on ceramic substrate.

Trim

– +

Gate

GND

Electrical Characteristics
Test conditions unless otherwise specified: TA = 25°C; VIN = 15 to 450V, COUT = 0.01µF
Symbol VOUT VOUT ∆VOUT ∆VOUT VIN IINQ IOFF IAUX ∆VOUT/∆VIN en IPEAK VAUX Output Voltage Output Voltage over Line Regulation Load...