Power Electronics

Over-Voltage Protection Device with USB/Charger-Detection Simplifies Design

Fairchild Semiconductor offers designers of cell phones, mobile audio, computer and consumer applications a highly integrated over-voltage protection (OVP) with USB/charger-detection. The FAN3989 incorporates an on-board FET and features built-in automatic detection allowing the device to sense the presence of a USB charger, all in a single package. This integrated automatic detection feature simplifies design by eliminating external circuitry, which in turn, saves 15 to 20 percent board space compared to discrete implementations. Its over-voltage protection capability is ideal for addressing emerging safety standards, which is particularly important for cell phones.

The FAN3989 acts as a USB connection monitoring device to determine if a USB device or a battery charging device is connected. The product will send a signal to the system controller to indicate the presence of a USB charging device. The FAN3989 also monitors VBUS for over or under-voltage conditions, setting the FLAG 2 pin low if VBUS is under 3.3V or over 6.0V, while turning off the internal PMOS load switch. These integrated features offer a more accurate approach when compared to typical discrete solutions.

“Recent issues regarding over-charging of portable devices have validated the need for increased protection,” said Bill Boldt, senior marketing manager, Signal Conditioning products. “Standards bodies are issuing over-voltage protection recommendations to increase the safety of handheld products. The FAN3989 is instrumental in addressing these concerns and ensuring the safety of phones using chargers that are connected to a USB port.”

The FAN3989 is packaged in ultra-compact 8-lead MLP packaging. It utilizes lead-free (Pb-free) terminals and has been characterized for moisture sensitivity in accordance with the Pb-free reflow requirements of the joint IPC/JEDEC standard J-STD-020.

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