General Description
The Supertex LR645 is a high input voltage, low output current
linear regulator. It has a 3-terminal fi xed output voltage version
available in TO-92, TO-220 and SOT-89 packages, as well as an
adjustable voltage version available in an 8- lead 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 startup circuit, it eliminates the
need for large power resistors. In this application, current is
drawn from the high voltage line only during start-up. Only leakage
current fl ows after start-up, thereby reducing the continuous
power dissipation to a few milliwatts.
Features
► Accepts inputs from 15V to 450V
► Output currents up to 3.0mA 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
Applications
► Off-line SMPS startup circuits (pulse loads)
► Low power off-line regulators
► Regulators for noisy inputs