Technical information

USB6B1

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2

Technical information

2.1

Surge protection

The USB6B1 is optimized to perform surge protection based on the rail to rail topology.

Note:

The estimations do not take into account phenomena due to parasitic inductances.

2.2

How to ensure good ESD protection

While the USB6B1 provides a high immunity to ESD surge, an efficient protection depends

on the layout of the board. In the same way, with the rail to rail topology, the track from the

possible to avoid overvoltages due to parasitic phenomena (see Figure 4.)

It’s often harder to connect the power supply near to the USB6B1 unlike the ground thanks

to the ground plane that allows a short connection. To ensure the same efficiency for

positive surges when the connections can’t be short enough, we recommend to putting a

overvoltage disturbances (see Figure 5.) The addition of this capacitor offers better

protection by providing a constant voltage during the surge.

Figure 6. shows the improvement of the ESD protection according to the recommendations

described above.

Important: An imortant precaution to take is to put the protection device closer to the disturbance

source (generally the connection).

Figure 4.

Surge behavior

Figure 5.

ESD behavior: optimized

layout and addition of a

100 nF capacitor

Lw

VI/O

ESD

SURGE

GND

I/O

+Vcc

Vf

Lw di

dt

Lw di

dt

Vcl+ = Vcc+Vf+Lw

di

dt

surge >0

-Vf- Lw

di

dt

surge <0

Vcl- =

t

tr=1ns

Vcc+Vf

Lw di

dt

Vcl+

POSITIVE

SURGE

-Lw

di

dt

t

tr=1ns

-Vf

Vcl-

NEGATIVE

SURGE

REF1=GND

VI/O

ESD

SURGE

I/O

REF2=+Vcc

C=100nF

Lw

Vcl+ = Vcc+Vf

-Vf

surge >0

surge <0

Vcl- =

t

Vcl+

POSITIVE

SURGE

t

Vcl-

NEGATIVE

SURGE