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| Maxim MAX15206低成本电源方案 |
| 作者： 时间：2008-07-31 来源:eaw |
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Maxim公司的 MAX15206是低成本小型4.5V-28V宽工作电压的DC/DC同步降压控制器,输出电压从输入电压的85%到低至0.6V,负载电流可高达25A. MAX15206的开关频率采用外接电阻可调,从200kHz到2MHz.可广泛应用在机顶盒(STB),LCD TV二次电源,交换机/路由器,电源模块,DSP电源和POL稳压器.本文介绍了MAX15206的主要性能,方框图以及工作电压4.5V-28V的应用电路图.
Low-Cost, Small, 4.5V to 28V Wide Operating Range, DC-DC Synchronous Buck Controller
The MAX15026 synchronous step-down controller operates from a 4.5V to 28V input voltage range and generates an adjustable output voltage from 85% of the input voltage down to 0.6V while supporting loads up to 25A. The device allows monotonic startup into a prebiased bus without discharging the output and features adaptive internal digital soft-start.
The MAX15026 offers the ability to adjust the switching frequency from 200kHz to 2MHz with an external resistor. The MAX15026’s adaptive synchronous rectification eliminates the need for an external freewheeling Schottky diode. The device also utilizes the external low-side MOSFET’s on-resistance as a current-sense element, eliminating the need for a current-sense resistor.
This protects the DC-DC components from damage during output overloaded conditions or output shortcircuit faults without requiring a current-sense resistor.
Hiccup-mode current limit reduces power dissipation during short-circuit conditions. The MAX15026 includes a power-good output and an enable input with precise turn-on/turn-off threshold, which can be used for input supply monitoring and for power sequencing.
Additional protection features include sink-mode current limit and thermal shutdown. Sink-mode current limit prevents reverse inductor current from reaching dangerous levels when the device is
sinking current from the output.
The MAX15026 is available in a space-saving and thermally enhanced 3mm x 3mm, 14-pin TDFN-EP package. The MAX15026 operates over the -40°C to +85°C temperature range.
MAX15206特性:
♦ 4.5V to 28V or 5V ±10% Input Supply Range
♦ 0.6V to (0.85 x VIN) Adjustable Output
♦ Adjustable 200kHz to 2MHz Switching Frequency
♦ Ability to Start into a Prebiased Load
♦ Lossless, Cycle-by-Cycle Valley Mode Current Limit with Adjustable, Temperature-Compensated Threshold
♦ Sink-Mode Current-Limit Protection
♦ Adaptive Internal Digital Soft-Start
♦ ±1% Accurate Voltage Reference
♦ Internal Boost Diode
♦ Adaptive Synchronous Rectification Eliminates External Freewheeling Schottky Diode
♦ Hiccup-Mode Short-Circuit Protection
♦ Thermal Shutdown
♦ Power-Good Output and Enable Input for Power Sequencing
♦ ±5% Accurate Enable Input Threshold
MAX15206应用:
Set-Top Boxes
LCD TV Secondary Supplies
Switches/Routers
Power Modules
DSP Power Supplies
Points-of-Load Regulators
图1. MAX15206方框图
图2. MAX15206的4.5V- 28V单电源应用电路图
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