Product LR8 High Voltage, Off-Line Summary Adjustable Three-pin Linear Regulator Sheet Now available in space-saving D-Pak V LR8 V IN OUT Applications 13.2V - 450V 1.2V - 438V ! Trickle battery chargers 10mA ! High voltage linear power supplies for ATE, controls and instrumentation ! LED and Relay drivers for instrumentation & control equipment (constant current operation) ! Lighting controls and consumer appliances ! Meter reader supply Product Overview: ! Switch mode power supply The LR8 is the industry’s first D-Pak three-pin, high voltage linear regulator with adjustable start-up (especially space output voltages (1.20V to 438V). The LR8 is designed for applications that require operation constrained applications) between 120VAC and 240VAC. The LR8 gives designers the flexibility to incorporate higher ! MEMs biasing supplies current capabilities at higher input voltages for a wide variety of cost-sensitive applications where ! “Universal” input power board space is at a premium. The device offers a 13.2V to 450V input voltage range, making it supplies ideal for universal off-line uses. Benefits: Features: Wide Supply Voltage Range Eliminates need for voltage selector switch in “Universal” input power supplies and allows worldwide usage with one design Tolerates circuit faults without blowing fuses Current Limit and Over Temperature Protection Accommodates many output voltage requirements Adjustable Output Voltage Conserves valuable PCB real estate TO-92, SOT-89 and D-Pak packages Low Quiescent Current Efficient with low loads When used for SMPS start-up. power consumption goes to nearly zero after start-up Discrete Implementation vs. LR8 Implementation: Discrete Implementation LR8 Implementation Disadvantages: Advantages: - High Quiescent Current - Lower Quiescent Current - Poor Regulation - Better Regulation - No Current Limit - Built-in Current Limiting - No Overtemperature Protection - Overtemperature Protection - Zener used to set regulation - 2 resistors set regulation - Higher efficiency 12/4/01 LR8 High Voltage, Off-Line Adjustable Three-pin Linear Regulator Operation: Except for its higher voltage capability, the LR8 operates like any other three-terminal adjustable linear regulator. A simple resistive voltage divider sets output voltage. A capacitor at the output is required for transient response and regulator stability. If applicable, a capacitor is required at the input to provide energy storage for rectified AC Startup Circuit for Switching Power Supply input. Constant Current Operation: The LR8 may be configured to provide a constant current output. The current is independent of both supply voltage and load impedance. Constant current operation allows this new device to be used in driving LEDs and trickle-charing NiCad batteries, as shown below. The trickle charger is used for applications that require battery backup Constant Current LED Driver NiCad Battery Trickle Charger (i.e. no cycling) such as emergency lights. Main Specifications: Input Voltage Range: 13.2V to 450V Output Current: 10mA max. Output Voltage Range: 1.2V to (V - 10V) Load Regulation: 3.0% INPUT Output Voltage Accuracy: +5% Line Regulation: 0.01%/V Power Dissipation: TO-92: 0.74W Supply Regulation: 60dB typ. @ 120Hz TO-243AA: 1.6W TO-252: 2.5W Ordering Information / Availability: Part Number Datasheet Samples Lead Time Package Options LR8 LR8 LR8N3, LR8N8, LR8K4 4 - 6 weeks ARO LR8N3 - TO-92 Now Now LR8N8 - TO-243AA LR8K4 - TO-252 LR8K4 D-Pak Product Contact If you have any questions regarding the LR8 or samples, contact Supertex Applications at: Telephone: (800) 222-9883 Fax: (408) 222-4895 Email: apps@supertex.com Web: www.supertex.com Supertex Sales: Contact your local Supertex Sales Office