UM5204EECD Datasheet, PDF (4/6 Pages) Union Semiconductor, Inc. – Quad Channel Low Capacitance ESD Protection Array

UM5204EECD
Applications Information
Device Connection Options for Protection of Four High-Speed Data Lines
This device is designed to protect data lines by clamping them to a fixed reference. When the
voltage on the protected line exceeds the reference voltage the steering diodes are forward biased,
conducting the transient current away from the sensitive circuitry. Data lines are connected at pins
1, 3, 4 and 6. Pin 2 should be connected directly to a ground plane. The path length is kept as short
as possible to minimize parasitic inductance. The positive reference is connected at pin 5. The
options for connecting the positive reference are as follows:
1. To protect data lines and the power line, connect pin 5 directly to the positive supply rail (VCC).
In this configuration the data lines are referenced to the supply voltage. The internal TVS diode
prevents over-voltage on the supply rail.
2. In applications where the supply rail does not exit the system, the internal TVS may be used as
the reference. In this case, pin 5 is not connected. The steering diodes will begin to conduct when
the voltage on the protected line exceeds the working voltage of the TVS (plus one diode drop).
3. In applications where complete supply isolation is desired, the internal TVS is again used as the
reference and VCC is connected to one of the I/O inputs. An example of this configuration is the
protection of a SIM port. The Clock, Reset, I/O, and VCC lines are connected at pins 1, 3, 4, and 6.
Pin 2 is connected to ground and pin 5 is not connected.
Protection of Four Data Lines and Power Supply Line
Protection of Four Data Lines using Internal TVS Diode
as Reference
Matte Tin Lead Finish
Matte tin has become the industry standard lead-free replacement for SnPb lead finishes. A matte
tin finish is composed of 100% tin solder with large grains. Since the solder volume on the leads
is small compared to the solder paste volume that is placed on the land pattern of the PCB, the
reflow profile will be determined by the requirements of the solder paste. Therefore, these devices
are compatible with both lead-free and SnPb assembly techniques. In addition, unlike other
lead-free compositions, matte tin does not have any added alloys that can cause degradation of the
solder joint.
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http://www.union-ic.com Rev.02 Jul.2012
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