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ACE735E 数据表(PDF) 5 Page - ACE Technology Co., LTD. |
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ACE735E 数据表(HTML) 5 Page - ACE Technology Co., LTD. |
5 / 10 page ACE735E 36V Input Standoff Voltage, 1.5A Step-Down Converter VER 1.1 5 FUNCTIONAL DESCRIPTIONS Loop Operation The ACE735E is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 1.5A of output current, integrated with a 300mΩ high side MOSFET. It uses a PWM current-mode control scheme. An error amplifier integrates error between the FB signal and the internal reference voltage. The output of the integrator is then compared to the sum of a current-sense signal and the slope compensation ramp. This operation generates a PWM signal that modulates the duty cycle of the power MOSFETs to achieve regulation for output voltage. Light Load Operation Traditionally, a fixed constant frequency PWM DC-DC regulator always switches even when the output load is small. When energy is shuffling back and forth through the power MOSFETs, power is lost due to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss is prominent and efficiency is therefore very low. ACE735E employs a proprietary control scheme that improves efficiency in this situation by enabling the device into a power save mode during light load,thereby extending the range of high efficiency operation. APPLICATION INFORMATION Setting Output Voltages Output voltages are set by external resistors. The FB threshold is 0.8V. RTOP = RBOTTOM x [(VOUT / 0.8) - 1] Inductor Selection The peak-to-peak ripple is limited to 30% of the maximum output current. This places the peak current far enough from the minimum overcurrent trip level to ensure reliable operation while providing enough current ripples for the current mode converter to operate stably. In this case, for 1.5A maximum output current, the maximum inductor ripple current is 500 mA. The inductor size is estimated as following equation: LIDEAL=(VIN(MAX)-VOUT)/IRIPPLE*DMIN*(1/FOSC) Therefore, for VOUT=5V, The inductor values is calculated to be L = 13μH. Chose 10μH or 15μH For VOUT =3.3V, The inductor values is calculated to be L = 9.2μH. Chose 10μH Output Capacitor Selection For most applications a no minal 22μF or larger capacitor is suitable. The ACE735E internal compensation is designed for a fixed corner frequency that is equal to For example, for VOUT =5V, L=15μH, C OUT =22μF. The output capacitor keeps output ripple small and ensures control-loop stability. The output capacitor must also have low impedance at the switching frequency. Ceramic, polymer, and tantalum capacitors are suitable, with ceramic exhibiting the lowest ESR and high-frequency impedance. Output ripple with a ceramic output capacitor is approximately as follows: VRIPPLE = IL(PEAK) [1 / (2π x f OSC x COUT)] If the capacitor has significant ESR, the output ripple component due to capacitor ESR is as follows: VRIPPLE(ESR) = IL(PEAK) x ESR |
类似零件编号 - ACE735E |
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类似说明 - ACE735E |
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