Supertex LR8

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifi cations is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The Supertex LR8 is a high voltage, low output current, adjustable linear regulator. Supertex LR8 has a wide operating inputvoltage range of 13.2V to 450V. The output voltage can be adjusted from 1.20V to 440V provided that the input voltage is at least 12V greater than the output voltage. The output voltage ofSupertex LR8 can be adjusted by means of two external resistors R1 and R2 as shown in the typical application circuits. The LR8 regulates the voltage difference between V_OUT and A_DJ pins to a nominal value of 1.20V. The 1.20V is amplifi ed by the external resistor ratio R1 and R2. An internal constant bias current of typically 10A is connected to the ADJ pin. This increases V_OUT by a constant voltage of 10A times R2.

The LR8 Supertex LR8 has current limiting and temperature limiting. The output current limit is typically 20mA and the minimum temperature limit is 125°C. An output short circuit current will therefore be limited to 20mA. When the junction temperature reaches Supertex LR8's temperature limit, the output current and/or output voltage will decrease to keep the junction temperature from exceeding its temperature limit. For SMPS start-up circuit applications, the LR8 turns off when an external voltage greater than the output voltage of the LR8 Supertex LR8 is applied to V_OUT of the LR8. To maintain stability, a bypass capacitor of 1.0F or larger and a minimum DC output current of 500A are required.

The Supertex LR8 is available in TO-243AA (SOT-89), TO-252 (DPAK), and TO-92 packages.