Source: https://www.reichelt.de/ICs-LMC-LS-/microchip/2/index.html?ACTION=2&LA=103&MANUFACTURER=microchip&GROUPID=5467
Timestamp: 2019-04-26 02:27:09+00:00

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LR12 is a high voltage, low output current, adjustable linear regulator. It has a wide operating input voltage range of 13.2 ... 100 V. The output voltage can be adjusted from 1.20 ... 88 V, provided that the input voltage is at least 12 V greater than the output voltage. The output voltage can be adjusted by means of two external resistors R1 and R2 as shown in the typical application circuits. The LR12 regulates the voltage difference between VOUT and ADJ pins to a nominal value of 1.20 V. The 1.20 V is amplified by the external resistor ratio R1 and R2. An internal constant bias current of typically 10 µA is connected to the ADJ pin. This increases VOUT by a constant voltage of 10 µA times R2. The LR12 has current limiting and temperature limiting. The output current limit is 100 mA maximum and the minimum temperature limit is 125°C. An output short circuit current will therefore be limited to 100 mA maximum. When the junction temperature reaches its 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 LR12 turns off when an external voltage greater than the output voltage of the LR12 is applied to VOUT of the LR12. To maintain stability, a bypass capacitor of 100 nF or larger and a minimum DC output current of 500 µA are required.
 Output current limiting, 50 mA min.
LR645 is a high input voltage, low output current linear regulator. It has a 3-terminal fixed 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 start-up 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 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 8.0 ... 12 V. This version can also be connected to an external depletion mode MOSFET for increased output current. When used in conjunction with depletion mode MOSFET DN2540N5, an output current of up to 150 mA is achieved.
LR645 is a high input voltage, low output current linear regulator. It has a 3-terminal fixed 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 start-up 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 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 8.0 to 12 V. This version can also be connected to an external depletion mode MOSFET for increased output current. When used in conjunction with depletion mode MOSFET DN2540N5, an output current of up to 150 mA is achieved.
LR745 is a high input voltage SMPS start-up circuit. The LR745 is ideally suited for use with industry standard low voltage PWM ICs having start thresholds of 13.9 to 18.0 V. It allows the PWM ICs to be operated from rectified 120 or 240 V AC lines, and eliminates the use of power resistors often used for this purpose. The internal circuitry of the LR745 allows the PWM ICs to operate at a VCC voltage below their start threshold voltage after start-up. The auxiliary voltage can be less than the start threshold voltage, which allows for improved efficiency.Current from the high voltage line is drawn only during the start-up period. After start-up, the internal high voltage line is disconnected from the IC, thereby reducing the continuous power dissipation to a minimum.
LR8 is a high voltage, low output current, adjustable linear regulator. It has a wide operating input voltage range of 13.2 ... 450 V. The output voltage can be adjusted from 1.20 ... 440 V provided that the input voltage is at least 12 V greater than the output voltage. The output voltage 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 VOUT and ADJ pins to a nominal value of 1.20 V. The 1.20 V is amplified by the external resistor ratio R1 and R2. An internal constant bias current of typically 10 µA is connected to the ADJ pin. This increases VOUT by a constant voltage of 10 µA times R2. The LR8 has current limiting and temperature limiting. The output current limit is typically 20 mA and the minimum temperature limit is 125°C. An output short circuit current will therefore be limited to 20 mA. When the junction temperature reaches its 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 is applied to VOUT of the LR8. To maintain stability, a bypass capacitor of 1.0 µF or larger and a minimum DC output current of 500 µA are required. The device is available in TO-243AA (SOT-89), TO-252 (D-PAK), and TO-92 packages.

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