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入力例：08/09/2022
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ヒント：複数の語句はコンマで区切ってください
Date
入力例：08/09/2022
Date
入力例：08/09/2022
Global
China (简体中文)
Japan (日本語)
Korea (한국어)
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Reverse Current Protection 101
Hi, everybody. My name is Zach, and today we're going to be taking a broad look at reverse current protection. We'll be starting off by going over the causes and risks associated with reverse current, then we'll talk about the options available to prevent reverse current. And afterwards we'll take a deeper dive into each of the solutions previously presented with an example from the Texas Instruments portfolio. So causes and risks of reverse current. Current is reversed when you hook a battery up to a component backwards or with the wrong polarity. It sends the current in the opposite direction it ought to be traveling to the circuit, which risks internal damage. Another cause of reverse current is accidental short circuits. When either of these situations occurs, damage might be caused to internal certain components, as pictured on the slide, or to battery itself. Neither of these obviously are good situations. So what can be done to prevent reverse current from damaging your system? On the high level, the flow of reverse current or the reverse bias voltage need to be very low to prevent damage. This can be insured by the use of a diode or a transistor. On the right, you can see examples of these devices, including the PNP and NPN flavors of transistors. Let's start off by talking about diodes. This is the simplest, cheapest way to get reverse current protection. So if you have a low-current application that needs protection from reverse current, diodes are the way to go. Drawbacks to keep in mind, however, include the forward voltage drop induced by the diode. This leads to shorter battery life, VCC limiting, and monitor power consumption by the circuit. The best way to mitigate these drawbacks is the use of a Schottky diode because of its lower forward drop. Two issues with the Schottky diodes, however, are that they're more expensive, and they have higher reverse current leakage. That may not be what you want in a reverse current protection situation. The other alternative is the use of a field effect transistor. This is useful when you need to maintain the integrity of your system's power efficiency and VCC because FETs have very low forward voltage drops. They also have the capability of handling higher current applications. However, FETs are more complex and more expensive than diodes. On the right, on the top picture, you can see it nMOSFET set into the ground path of a circuit. And on the bottom picture, you can see a pMOSFET set into the power path of a circuit. These nMOSFETs work by orienting the body diode in the direction of normal current flow so that when the battery is installed incorrectly, the mMOSFETs gate voltage is low, preventing it from turning on and preventing reverse current from flowing. However, when the battery is installed correctly, the gate voltage is high, and this channel shorts out the ground. For pMOSFETs, it's pretty much the same deal, except for the gate voltage is opposite. It goes low for the circuit. Let's wrap up by taking a look at a real-life example of reverse current protection from the Texas Instruments Load Switch Portfolio. This is the TPS22964C, which is a low on resistance 3 amp load switch with reverse current protection. Looking at the pictures at the bottom right, you can see a comparison of the TPS22964C's integrated reverse current protection system on the red board compared to a standalone MOSFET on the left. The integrated reverse current protection solution from Texas Instruments has a much smaller package size, somewhere around 1.4 by 0.9 millimeters, as compared to the standalone MOSFET at 13 times 2.5 millimeters. Not only that, but the TPS22964C has a myriad of other features besides integrated reverse current protection in a very small and affordable package size. So guys, if you liked the video and want to find out more about reverse current protection or TI's Portfolio products with reverse current protection, just visit ti.com/loadswitch and you'll get all the information you need. Thanks for tuning in.
説明
2015年 8月 13日
Learn about the risks, causes and prevention of reverse current protection,
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