rclamp0514m Semtech Corporation, rclamp0514m Datasheet - Page 6

• Manufacturer Part Number: rclamp0514m
• Description: Railclamp Low-capacitance Tvs Diode Array
• Manufacturer: Semtech Corporation

ESD Protection With RailClamps
RailClamps are optimized for ESD protection using the
rail-to-rail topology. Along with good board layout, these
devices virtually eliminate the disadvantages of using
discrete components to implement this topology. Con-
PIN Descriptions
sider the situation shown in Figure 4 where discrete
diodes or diode arrays are configured for rail-to-rail
protection on a high speed line. During positive duration
ESD events, the top diode will be forward biased when
the voltage on the protected line exceeds the reference
voltage plus the V
events, the bottom diode will be biased when the voltage
exceeds the V
clamping voltage due to the characteristics of the protec-
tion diodes is given by:
V
V
However, for fast rise time transient events, the effects of
parasitic inductance must also be considered as shown
in Figure 5. Therefore, the actual clamping voltage seen
by the protected circuit will be:
V
V
ESD current reaches a peak amplitude of 30A in 1ns for
a level 4 ESD contact discharge per IEC 61000-4-2.
Therefore, the voltage overshoot due to 1nH of series
inductance is:
V = L
Example:
Consider a V
steering diode and a series trace inductance of 10nH.
The clamping voltage seen by the protected IC for a
positive 8kV (30A) ESD pulse will be:
V
This does not take into account that the ESD current is
directed into the supply rail, potentially damaging any
components that are attached to that rail. Also note
PROTECTION PRODUCTS
Applications Information (continued)
C
C
C
C
C
= V
2005 Semtech Corp.
= V
= -V
= -V
= 5V + 30V + (10nH X 30V/nH) = 335V
P
CC
CC
di
F
F
+ V
- L
+ V
ESD
G
/dt = 1X10
F
F
di
CC
+ L
F
ESD
= 5V, a typical V
of the diode. At first approximation, the
(for positive duration pulses)
(for negative duration pulses)
P
/dt
di
F
drop of the diode. For negative
ESD
/dt (for positive duration pulses)
-9
(30 / 1X10
(for negative duration pulses)
F
of 30V (at 30A) for the
-9
) = 30V
6
When Using Discrete Components to Implement
When Using Discrete Components to Implement
When Using Discrete Components to Implement
When Using Discrete Components to Implement
When Using Discrete Components to Implement
Figure 5 - The Effects of Parasitic Inductance
Figure 5 - The Effects of Parasitic Inductance
Figure 5 - The Effects of Parasitic Inductance
Figure 5 - The Effects of Parasitic Inductance
Figure 5 - The Effects of Parasitic Inductance
Figure 4 - “Rail-
Figure 4 - “Rail-T T T T T o-Rail” Pr
Figure 4 - “Rail-
Figure 4 - “Rail-
Figure 4 - “Rail-
Figure 6 - Rail-
Figure 6 - Rail-T T T T T o-Rail Pr
Figure 6 - Rail-
Figure 6 - Rail-
Figure 6 - Rail-
Rail-
Rail-
Rail-T T T T T o-Rail Pr
Rail-
Rail-
RailClam
RailClam
RailClam
RailClam
RailClamp T
(First Approximation)
(First Approximation)
(First Approximation)
(First Approximation)
(First Approximation)
o-Rail Pr
o-Rail Pr
o-Rail Pro o o o o t t t t t ection
o-Rail Pr
o-Rail” Pr
o-Rail” Pro o o o o t t t t t ection T
o-Rail” Pr
o-Rail” Pr
o-Rail Pr
o-Rail Pr
o-Rail Pro o o o o t t t t t ection Using
o-Rail Pr
p T
p TV V V V V S Arra
p T
p T
RClamp0514M
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PRELIMINARY
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