PolyZen Device Helps Protect Portable Electronics from Charger-Induced Failure
The widespread availability of external and universal power supplies has made charger-induced system failure a leading cause of device warranty returns. Designing in additional safeguards to help prevent damage that may be caused by the use of unauthorized charging systems is complicated by the fact that the solution itself must accommodate smaller electronic packages.
The most cost-effective way to implement a power bus for portable electronics is with a standard DC barrel jack. However, because this connector is so commonly used, the user may accidentally connect the incorrect power supply to electronic equipment at home or while traveling. Faults may also occur when using commercially available universal power supplies that come with a variety of connectors. These devices allow the user to dial in the voltage to levels as high as 24V, as well as switch polarity.
Transient protection is especially critical when designing peripherals that may be powered off computer buses and automotive power buses. Automotive power buses are notoriously dirty. Although they are nominally 12V, they can range in normal operation from 8V to 16V. Still, battery currents can exceed 100 Amps and be stopped instantly via a relay or fuse, generating large inductive spikes on the bus and increasing voltage by five times or more.
Although typical computer power supplies provide regulated lines at 5V +/-5%, and 12V +/-5%, under certain circumstances the voltage at these lines may exceed 5.25V and 12.6V, causing damage to the system or unprotected peripherals. Voltage spikes can occur when there is inductance in the power bus and a rapid change in current occurs. This change can result from a hot disconnect of a peripheral, an internal system shutdown, or other internal power fluctuations.
Under the new USB 3.0 specification, high-powered devices will be able to source up 0.9A of current, and new types of powering devices, such as Powered-B connector devices, may provide up to 1A, as opposed to 0.5A in the USB 2.0 specification. These higher current applications require more reliable and robust circuit protection to help prevent damage caused by overvoltage transients and overcurrent conditions. PolyZen devices are designed to help lock out inappropriate power supplies. The device is particularly effective at clamping and smoothing inductive voltage spikes. In response to an inductive spike, the device’s Zener diode element shunts current to ground until the voltage is reduced to the normal operating range. In the case of a wrong-voltage power supply, the device clamps the voltage, shunts excess power to ground, and eventually locks out the wrong supply.
The relatively flat voltage vs. current response of the PolyZen device helps clamp the output voltage, even when input voltage and source currents vary. It helps provide coordinated protection with a component that protects like a Zener diode, but is capable of withstanding very-high-power fault conditions – without requiring any special heat-sinking structures beyond normal PCB traces.
Benefits:
● Helps shield downstream electronics from overvoltage and reverse bias
● Trip events shut out overvoltage and reverse bias sources
● Analog nature of trip events minimize upstream inductive spikes
● Helps reduce design costs with single component placement and minimal heat sinking requirements
Features:
● Hold currents up to 2.6A
● Power handling on the order of 30 watts
● Stable VZ vs. fault current
● Time delayed, overvoltage trip
● Time delayed, reverse-bias trip
● Power handling on the order of 100 watts
● Integrated device construction
● RoHS compliant
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ZEN056V130A24LS 、 ZEN059V130A24LS† 、 ZEN065V130A24LS 、 ZEN098V130A24LS 、 ZEN132V130A24LS 、 ZEN164V130A24LS 、 ZEN056V230A16LS 、 ZEN065V230A16LS 、 ZEN098V230A16LS 、 ZEN132V230A16LS 、 ZEN056V075A48LS 、 ZEN132V075A48LS 、 ZEN056V115A24LS 、 ZEN056V130A16YM 、 ZEN056V175A12YM 、 ZEN132V130A16YM 、 ZEN132V175A12YM 、 ZEN056V130A24YC 、 ZEN056V230A16YC 、 ZEN056V260A16YC 、 ZEN132V130A24YC 、 ZEN132V230A16YC 、 ZEN132V260A16YC |
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[ Cell phones ][ PDAs ][ Personal Navigation Devices ][ MP3 players ][ DVD players ][ Digital cameras ][ USB hubs ][ Printers ][ Scanners ][ Hard Disk Drives ][ Desk phones ][ PBX phones ] |
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Application note & Design Guide |
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Please see the document for details |
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English Chinese Chinese and English Japanese |
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2016/11/23 |
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2.3 MB |
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