전자부품 데이터시트 검색엔진 |
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PAC5255 데이터시트(PDF) 23 Page - Active-Semi, Inc |
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PAC5255 데이터시트(HTML) 23 Page - Active-Semi, Inc |
23 / 74 page PAC5255 Power Application Controller The MMSS detects and selects between high-side and low-side mode during start up based on the placement of the current sense resistor and the CSM pin voltage. It employs a safe start up mode with 9.5kHz switching frequency until VP exceeds 4.3V under-voltage-lockout threshold, then transitions to the 45kHz default switching frequency for at least 6ms to bring VP close to the target voltage, before enabling the linear regulators. Any extra load should only be applied after the supplies are available and the microprocessor has initialized. The switching frequency can be reconfigured by the microprocessor to be 181kHz to 500kHz in the high switching frequency mode for battery-based applications, and to be 45kHz to 125kHz in the low switching frequency mode for AC applications. Upon initialization, the microcontroller must reconfigure the MMSS to the desired settings for VP regulation voltage, switching mode, switching frequency, and VHM clamp. Refer to the PAC application notes and user guide for MMSS controller design and programming. If a stable external 4.5V to 18V power source is available, it can power the VP main supply and all the linear regulators directly without requiring the MMSS controller to operate. In such applications, VHM can be connected directly to VP and the microcontroller should disable the MMSS upon initialization to reduce power loss. 10.3.2. Linear Regulators The MMPM includes up to four linear regulators. The system supply regulator is a medium voltage regulator that takes the VP supply and sources up to 200mA at REGO until VSYS, externally coupled to REGO, reaches 5V. This allows a properly rated external resistor to be connected from REGO to VSYS to close the current loop and offload power dissipation between VP and VSYS. Once VSYS is above 4V, the three additional 40mA linear regulators for VCCIO, VCC33, and VCC18 supplies sequentially power up. Figure 10-5 shows typical circuit connections for the linear regulators. For 5V I/O systems, short the VCCIO pin to VSYS to bypass the VCCIO regulator. For 3.3V I/O systems, the VCCIO regulator generates 3.3V. The VCC33 and VCC18 regulators generate 3.3V and 1.8V, respectively. When VSYS, VCCIO, VCC33, and VCC18 are all above their respective power good threshold, and the configurable power on reset duration has expired, the microcontroller is initialized. - 23 - Rev 1.10‒March 3, 2018 Figure 10-4. AC/DC Flyback Mode PAC5255 VHM DRM CSM VP V P (12V default) V AC (120V/230V) |
유사한 부품 번호 - PAC5255_18 |
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유사한 설명 - PAC5255_18 |
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