APPLICATION NOTE
PSRDA3.3-4
thru
PSRDA15-4
The PSRDAxx-4 Series are low capacitance, unidirectional TVS arrays that are designed to protect I/O or high speed data lines from the damaging
effects of ESD or EFT. This product series has a surge capability of 500 Watts PPP per line for an 8/20µs waveshape and offers ESD protection >
40kV.
DIFFERENTIAL-MODE CONFIGURATION (Figure 1)
Ideal for use in USB applications, the PSRDAxx-4 Series provides up
to four (4) lines of protection in a differential-mode configuration as
depicted in Figure 1.
Circuit connectivity is as follows:
✔ Pins 1, 4, 6 and 7 are connected to the data lines.
✔ Pins 5 and 8 are connected to ground.
✔ Pins 2 and 3 are connected to the databus.
DIFFERENTIAL-MODE CONFIGURATION (Figure 2)
Figure 1. Typical Differential-Mode USB Protection
USB PORT
D+
VBUS
VBUS
D-
GND
4
3
2
1
The PSRDAxx-4 Series also provides up to four (4) lines of protection
in a differential-mode configuration as depicted in Figure 2 for T1/E1
applications.
Circuit connectivity is as follows:
✔ Pins 1, 4, 6 and 7 are connected to the data lines.
✔ Pins 5 and 8 are connected to ground.
✔ Pins 2 and 3 are connected to the databus.
CIRCUIT BOARD LAYOUT RECOMMENDATIONS
Circuit board layout is critical for Electromagnetic Compat-
ibility (EMC) protection. The following guidelines are
recommended:
✔ The protection device should be placed near the input
terminals or connectors, the device will divert the
transient current immediately before it can be coupled
into the nearby traces.
✔ The path length between the TVS device and the
protected line should be minimized.
✔ All conductive loops including power and ground
loops should be minimized.
5
6
7
8
GND
GND
USB PORT VBUS
D+
D-
GND
Figure 2. Typical Differential-Mode T1/E1 Protection
RTIP
RRING
4
3
2
1
PTC
PLC01-
6
PTC
✔ The transient current return path to ground should be
kept as short as possible to reduce parasitic induc-
tance.
✔ Ground planes should be used whenever possible.
For multilayer PCBs, use ground vias.
5
6
7
8
TTIP
GND
GND
PTC
TRING
PLC01-
6
PTC
05096.R7 4/05
4
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