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© 2010 Semtech Corp.
www.semtech.com
PROTECTION PRODUCTS
RClamp3654PA
Applications Information
Figure 2 - USB ProtectionFigure 2 - USB Protection
Figure 2 - USB ProtectionFigure 2 - USB Protection
Figure 2 - USB Protection
Figure 1- Pin Configuration & Circuit Diagram
Device Connection Options for Protecting One USB
Port
USB Data and ID lines are connected at pins 1, 2, and
3. These inputs are referenced to an internal 5 volt
TVS protection device. When the voltage on these
lines exceed 5 volts, the TVS will conduct. Pin 6 is
connected to the USB voltage bus (VBus). This device
will conduct when the voltage on the bus exceeds 28
volts. The center tab is connected to ground. The
path length should also be kept as short as possible to
minimize parasitic inductance. For best results,
multiple micro-vias are recommended to the ground
plane.
Protecting USB Interfaces
The RClamp3654PA is optimized for use on systems
that utilize the USB interface for battery charging. Low
capacitance protection is provided for the USB data
(DM, DP) and USB ID pins. The maximum capacitance
on these lines is <1pF for maximum signal integrity.
All three lines are referenced to an internal 5 volt TVS
device. A separate 28 volt TVS device is used for
protection of the USB voltage bus. This allows battery
charging without signal clipping. A typical example is
shown in Figure 2.
VBus
Mini USB
DM
USB ID
GND
1
Gnd
1
2
3
4
5
DP
12 3
GND
6
5.5V
28V
