1255P Datasheet, PDF (7/10 Pages) Gennum Corporation – Protects USB VBus operating up to 12V

PROTECTION PRODUCTS
Applications Information
Device Connection and Layout Options for Protecting
One USB Port
The RClamp1255P is optimized for protection of USB
ports. Low capacitance protection is provided for the
USB data (DM, DP) and USB ID pins. The maximum
capacitance on these lines is <0.5pF for maximum
signal integrity. USB Data and ID lines are connected
at pins 2, 3, and 4. These inputs are referenced to
an internal 4 volt TVS protection device. When the
voltage on these lines exceed 4 volts, the TVS will
conduct. Pin 1 is connected to the USB voltage bus
(VBus). This device will conduct when the voltage on
the bus exceeds 12 volts. Ground is provided at pins
5, 6, and the center tabs. Multiple micro vias
connected to ground are recommended for best ESD
performance. This will reduce parasitic inductance in
the ground path and minimize the clamping voltage
seen by the protected device.
RClamp1255P
PRELIMINARY
VBus
D+
D-
ID
GND
GND
GND
GND
Figure 1 - Pin Configuration (Top View)
2
3
4
4V
1
12V
5, 6,
Tabs
Figure 2 - Schematic
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