Designed for use with analog and digital satellite receivers, this single low-noise step-down conversion regulator (LNBR) is a monolithic linear circuit with a conversion voltage regulator designed to transmit power and interface signals to an LNB buck converter over coaxial cables. The A8291 requires few external components and has a boost switch and compensation circuitry integrated into the device. Choose a higher switching frequency to minimize the size of the passive filter element and further reduce costs. The high level of component integration ensures extremely low noise and pulsating graphics.
The A8291 is designed to achieve high efficiency by leveraging Allegro's® advanced BCD processes. Optimized for integrated boost switches to minimize switching and static losses. To further improve efficiency, it is necessary to minimize voltage drop during the tracking regulator.
The A8291 features an integrated tone detection feature that fully supports both DiSEqC™ communications. Several modes are available to use an internal or external clock source to generate a tonal signal throughout the process until no load. The DiSEqC™ filter bypass switch has been integrated to minimize output impedance during tone production.
The device provides a comprehensive set of fault registers that meet all common criteria, including: overcurrent, overtemperature shutdown, undervoltage, cable disconnection, power failure, and tone detection.
The device uses a 2-wire bidirectional serial interface, is compatible with the I2C™ standard, and operates at 400 kHz.
The A8291 is available in a lead-free, 28-pin MLP/QFN package.
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2 线串行 I2C™兼容接口：控制（写入）和状态（读取）
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LNB 电压（16 个可编程级别）与所有普通标准兼容
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最低耗散跟踪开关模式电源转换器
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集成转换器开关和电流感测
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提供高达 500 毫安的载荷电流
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静态电流限制电路允许启动时的满电流、13→18 V 输出转换、可靠的启动宽载荷范围
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推拉输出级可最小化高电容性载荷的 13→18 V 和 18→13 V 输出转换次数
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通过外部计时电容器可调升/降时间
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内置音调振荡器、出厂校准到 22 千赫，有助于 DiSEqC™ 音调编码，甚至在无载荷时
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通过 I2C™ 数据位和/或外部引脚可实现四种 22 千赫音调生成方法
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过滤旁路 MOSFET 最小化音调发射过程中的损耗
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22 千赫音调探测器有助于 DiSEqC™ 2.0 解码
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辅助调制输入
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带计时器 LNB 过电流
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输出电压水平、输入电源 UVLO 和 DiSEqC™ 音调输出诊断
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电缆断开诊断