Application information USBDFxxW5
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Figure 7. Remaining voltage at both stages S1 (V
input
) and S2 (V
output
) during ESD
surge
Note that the USBDFxxW5 is not only acting for positive ESD surges but also for negative
ones. Negative disturbances are clamped close to ground voltage as shown in Figure 7.b.
2.3 Latch-up phenomena
The early ageing and destruction of IC’s is often due to latch-up phenomena which is mainly
induced by dV/dt. Thanks to its structure, the USBDFxxW5 provides a high immunity to
latch-up phenomena by smoothing very fast edges.
2.4 Crosstalk behaviour
Figure 8. Crosstalk phenomena
The crosstalk phenomena is due to the coupling between 2 lines. The coupling factor ( β12
or β21 ) increases when the gap across lines decreases, this is the reason why we provide
crosstalk measurements for a monolithic device to guarantee negligeable crosstalk between
the lines. In the example above, the expected signal on load R
L2
is α
2
V
G2
, in fact the real
voltage at this point has got an extra value β21V
G1
. This part of the V
G1
signal represents
the effect of the crosstalk phenomenon of the line 1 on the line 2. This phenomenon has to
be taken into account when the drivers impose fast digital data or high frequency analog
signals in the disturbing line. The perturbed line will be more affected if it works with low
voltage signal or high load impedance (few kΩ).
A. Positive surge B. Negative surge
Line 1
Line 2
V
G1
V
G2
R
G1
R
G2
DRIVERS
R
L1
R
L2
RECEIVERS
αβ
1 G1 1 2 G2
V+ V
αβ
2 G2 2 1 G1
V+ V
