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2022-09-24 22:26:30
LR745-High input voltage switching power supply startup circuit
General description
The Supertex LR7 is a high input voltage switching power supply start-up circuit. The LR7 is ideal for use with industry standard voltage PWM ICs with a 13.9V to 18.8V start-up threshold. This enables the PWM IC to operate from or correct 120V to 240V AC lines and eliminates the power resistors often used for this purpose. The LR7 internal circuit allows the PWM ICs to operate after their start-up thresholds are below the VCC voltage after start-up. The auxiliary voltage can be less than the startup threshold voltage, which allows for improved efficiency. The current from the high voltage line is only drawn during the start-up period. After startup, the internal high voltage lines are disconnected from the IC thereby reducing continuous power dissipation to a minimum. ...
Features The operating input voltage range from 450V to 25V is compatible with industry standard PWM integrated circuits. See application notes AN-H28 and AN-H29.
Output current limit for PWM, start-up threshold voltage IC13.9V to 18.8V very low power consumption after start-up
Applications Notebook and Notebook Communication Power Battery Chargers Motor Controllers