sfc2280-68 Semtech Corporation, sfc2280-68 Datasheet - Page 7

• Manufacturer Part Number: sfc2280-68
• Description: Sfc2280-68 Chipclamp? Headset Microphone Emi Filter And Esd Protection
• Manufacturer: Semtech Corporation

SFC2280-68
PRELIMINARY
PROTECTION PRODUCTS
Applications Information (Continued)
Voltage Clamping Characteristics.
Figure 3 - Clamping Characteristic Model
The clamping characteristics of the SFC2280-68 are
optimized by the use of two TVS diodes in the protec-
tion circuit (Figure 3). An ESD strike on the protected
line will be initially suppressed by the first TVS diode.
The voltage across the TVS will be the clamping voltage
of the device (V
) given by:
C1
V
= V
+ R
* I
C1
br
D
PP
where
V
= Breakdown voltage of the TVS
br
R
= Dynamic resistance of the TVS
D
I
= Peak pulse (ESD) current
PP
The dynamic resistance of the TVS is very small,
typically < 0.5 .
The second TVS will be subjected to V
through the
C1
voltage divider formed by the series resistor (R) and
the dynamic resistance of the TVS. Since R >> RD
then by the voltage divider theorem, the voltage seen
by the protected IC will be a slightly above the break-
down voltage (V
) of the second TVS.
br
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