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Moteur de recherche de fiches techniques de composants électroniques |
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Moteur de recherche de fiches techniques de composants électroniques |
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SI9169BQ-T1-E3 Fiches technique(PDF) 6 Page - Vishay Siliconix |
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SI9169BQ-T1-E3 Fiches technique(HTML) 6 Page - Vishay Siliconix |
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6 / 10 page  www.vishay.com 6 Document Number: 70945 S-72058-Rev. E, 08-Oct-07 Vishay Siliconix Si9169 FUNCTIONAL BLOCK DIAGRAM DETAIL OPERATIONAL DESCRIPTION Start-Up The UVLO circuit prevents the internal MOSFET switches and oscillator circuit from turning on, if the voltage on VDD pin is less than 2.5 V. With typical UVLO hysteresis of 0.1 V, controller is continuously powered on until the VDD voltage drops below 2.4 V. This hysteresis prevents the converter from oscillating during the start-up phase and unintentionally locking up the system. Once the VDD voltage exceeds the UVLO threshold, and with no other shutdown condition detected, an internal Power-On-Reset timer is activated while most circuitry, except the output driver, are turned on. After the POR timeout of about 1 ms, the internal soft-start capacitor is allowed to charge. When the soft-start capacitor voltage reaches 0.5 V, the PWM circuit is enabled. Thereafter, the constant current charging the soft-start capacitor will force the output voltage to rise gradually without overshooting. To prevent negative undershoot, the synchronous switch is tri-stated until the duty cycle reaches about 10 %. In tri-state, the high-side P-Channel MOSFET is turned off by pulling up the gate voltage to VS potential. The low-side N-Channel MOSFET is turned off by pulling down the gate voltage to PGND potential. Note that the Si9169 will always soft starts in the PWM mode regardless of the voltage level on the PWM/PSM pin. Shutdown The Si9169 is designed to conserve as much battery life as possible by decreasing current consumption of IC during normal operation as well as the shutdown mode. With logic low level on the SD pin, current consumption of the Si9169 is decreased to less than 1 µA by shutting off most of the circuits. The logic high enables the controller and starts up as described in "Start-Up" section above. Reference Threshold Generator Oscillator PSM Modulator PWM Modulator Soft-Start Timer UVLO POR Bias Generator OTP Drivers PWM/PSM Select VDD SD VS VIN/OUT GND PGND Positive Supply COIL Negative Return and Substrate P N PWMEN PSMEN PWMIN PSMIN 0.5 V 1.0 V Ramp COSC VREF VO FB COMP SYNC ROSC PWM/PSM MODE |
Numéro de pièce similaire - SI9169BQ-T1-E3 |
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Description similaire - SI9169BQ-T1-E3 |
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