TI公司TPS7A78智能AC/DC线性电压稳压器

TI公司的TPS7A78是120mA智能AC/DC线性电压稳压器，在容易使用非磁性AC/DC转换方案中提高了整个效率和待机功耗.TPS7A78采用外接电容来创立电流源和箝位整流电压。器件的独特架构允许其待机功耗能从几百毫瓦降低到十几毫瓦.TPS7A78非隔离功率解决方案的输入电压70 VAC到 270VAC45 Hz 到65 Hz，高达75%的效率，支持输出电压从1.25V到5V，待机功耗15mW，线路压降电容器为线性解决方案尺寸的1/4，对火线电压，负载和温度的精密电压调整达到3%精度，具有电源故障检测和电源良好指示。主要用在工厂自动化，建筑物自动化，白色家电，电能表表，烟雾检测器和恒温器控制。本文介绍了TPS7A78主要特性，功能框图，单相AC电源和三相AC电源图，单相E表电源图以及评估模块TPS7A78EVM-011主要特性和电指标性能，电路图，材料清单和PCB设计图。

The TPS7A78 improves the overall efficiency andstandby power in power supplies for an easy-to-usenon-magnetic approach to AC/DC conversion. TheTPS7A78 uses an external capacitor to create acurrent source and actively clamps the rectifiedvoltage. The device then regulates the voltage downto the application-specific operating voltage. Theunique architecture of the device allows the standbypower to be reduced from several 100s of milliwattsto just a few 10s of milliwatts. The TPS7A78 takesadvantage of an innovative switched capacitor stageto reduce the clamped voltage down byapproximately 1/4th of the value， which in turnmultiplies the current by 4. Thus， the current sourcecapacitor can be much smaller in size， whichminimizes standby power， reduces solution size， andcan lead to a lower system cost.

The TPS7A78 is optimized for e-meteringapplications where the power supply must be reliableand magnetic tamper-proof. The TPS7A78 requiresno external magnetics， which makes complying withIEC 61000-4-8 easier while minimizing costlymagnetic shielding in e-metering applications.

Additionally， the TPS7A78 also comes with a userprogrammablepower-fail detection threshold that canprovide an early alert to power failures so the systemcan save data before completely losing power. Apower-good indication can also be used forsequencing or to provide a reset to a micro-controller.

The TPS7A78 is available in a 14-pin TSSOP （PWP）package.

TPS7A78主要特性：

1? Non-isolated power solution for 70 VAC to 270VAC， 45 Hz to 65 Hz （bench tested）：

– Up to approximately 75% efficiency

? Supports output voltages from 1.25 V to 5 V

? Standby power consumption： 15 mW （cap-drop =150 nF）

? Line voltage drop capacitor can be 1/4th the sizeof linear solutions

? Power-fail detection

? Power-good indication

? 3% precision voltage regulation over line， load，temperature

? Package：

– 5-mm × 6.5-mm TSSOP-14 （PWP）

TPS7A78应用：

? Factory automation

? Building automation

? White goods

? Electricity Meters （E-Meters）

? Smoke detectors

? Thermostat controls

图1. TPS7A78功能框图

图2. TPS7A78单相AC电源图

图3. TPS7A78三相AC电源图

图4. TPS7A78单相E表电源图

评估模块TPS7A78EVM-011

This user’s guide describes the operational use of the TPS7A78EVM-011 evaluation module （EVM） as areference design for engineering demonstration and evaluation of the TPS7A78， non-isolated smart linearvoltage regulator （LDO）。 Included in this user’s guide are setup and operating instructions， thermal andlayout guidelines， a printed circuit board （PCB） layout， a schematic diagram， and a bill of materials （BOM）。

Throughout this document， the terms demonstration kit， evaluation board， and evaluation module aresynonymous with the TPS7A78EVM-011.

Texas Instruments’TPS7A78EVM-011 helps design engineers evaluate the operation and performance ofthe TPS7A78 smart linear voltage regulator for possible use in their own circuit application. This particularEVM is intended for evaluation purposes and is not intended to be an end product. The EVM configurationcontains a single 3.3-V output regulator optimized for e-metering applications. The TPS7A78EVM-011regulates VAC supply to 3.3-V DC supply and can source up to 27 mA （max） current.

The EVM also features a power-fail detection signal and a power-good indication signal to warrant a VACsupply failure and to indicate to a microcontroller （MCU） that the regulated DC voltage is greater than 90%of the targeted regulation DC voltage.