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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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ACT4921QI Fiches technique(PDF) 22 Page - Active-Semi, Inc |
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ACT4921QI Fiches technique(HTML) 22 Page - Active-Semi, Inc |
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22 / 35 page  ACT4921QI Rev 1.0, 18-Jan-2018 Innovative PowerTM www.active-semi.com ActiveSwitcherTM is a trademark of Active-Semi Copyright © 2018 Active-Semi, Inc. 22 AGND The AGND pin is the IC’s analog ground pin. It is a “quiet” ground pin that is separate and isolated from the high power, high current carrying PGND ground plane. Connect the non-power components to AGND. AGND must be kelvin connected to the PGND pin in a single location. COMP COMP is the output of a transconductance amplifier that is used to compensate the internal buck converter. The compensation components, which are typically a standard type-2 compensation should be grounded to the AGND pin. See the Application section for more information on compensating the internal buck converter. PLI PLI (Power Loss Indicator) goes high after softstart and stays high in normal operation. PLI immediately goes low when the IC enters supplement mode. This setting is used to let the system uP know that power loss is imminent. The PLI pin is an open-drain output and is 5V compliant. FB The FB pin is used to regulate the buck converter output voltage when the IC is in supplement mode. HSB HSB provides power to the internal high-side MOSFET gate driver circuitry. Connect a 47nF capacitor from HSB pin to SW pin. SW SW is the switch node for the internal buck and boost converters. Connect the inductor to the SW pin. VOUT VOUT is the output of the eFuse and connects to the system load. The eFuse connects VOUT to VIN in normal operation, and it disconnects it in supplement mode. VB VB is the output pin from the blocking FET. Depending on the operating mode, power either flows into or out of VB. In normal operation, power flows from VIN, through the eFuse and blocking FETs and out of VB to provide input power to the boost converter. ENB must be pulled high to enable this functionality. During supplement mode, the buck converter output power flows into VB, through the blocking FET, and out of VOUT to the system. DISCHG DISCHG is the discharge pin for the storage capacitors. When the IC enters the UV/POR state, DISCHG is internally connected to PGND through an internal FET. Connect a resistor between DISCHG and STR to quickly discharge the storage capacitance. The user can manually turn on the DISCHG FET by setting the DISCHG_STR bit to 1. The discharge function is typically only used during product development and evaluation. It allows the user to quickly discharge large storage capacitor values between testing to ensure the next power cycle starts with discharged capacitors. If the function is not used in production, the discharge resistor can be removed from the board and the DISCHG pin can be connected to PGND or left open. The discharge resistor should be chosen to keep the discharge current less than 100mA. PG_STR PG_STR is a power good indicator for the storage capacitors. It goes high when the storage capacitor voltage goes into regulation. It goes low when the voltage drops below 95% of the setpoint. It also goes low when either the buck or boost converter is disabled. It is open drain and is 5V compliant. PG_VO PG_VO is a power good indicator for VOUT. It goes high when the eFuse is fully turned on. In supplement mode, it starts high and then goes low when the FB pin drops below 95% of VFB_REF (0.8V). It is open drain and is 5V compliant. General Description eFuse The ACT4921 eFuse is an “electronic” fuse that disconnects the input from the output. It has considerable advantages over mechanical fuses because it has adjustable current thresholds and it resets after the fault condition is gone. The eFuse consists of two back-to-back MOSFETS to provide bi- directional protection. This provides protection against both input and output short circuit conditions by preventing current flow in both directions. Hot swap functionality is provided by the eFuse softstart function and current limiting circuitry. This prevents large inrush |
Numéro de pièce similaire - ACT4921QI |
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Description similaire - ACT4921QI |
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