ESD Circuit Protection Solutions
CIRCUIT
PROTECTION
SOLUTIONS
CIRCUIT
PROTECTION
SOLUTIONS
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Modified_010408
CIRCUIT
PROTECTION
SOLUTIONS
Decrease in on-chip ESD protection
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Modified_010408
Manufacturers are reducing the space they are will
to devote to on-chip ESD protection structures….
E
S
D
Functional
die space
E
S
D
Integrated circuits have used
on-chip protection to ensure
high yields through the
foundry and packaging
processes. Typical levels of
protection are 1kV to 2kV.
Maintaining ESD space usage increases ESD cost per
die since the space required by functional circuits
continues to decrease
Processor, ASIC, etc.
Functional
die space
2004
Processor, ASIC, etc.
E
S
D
2000
E
S
D
KEY UPDATE: The Industry Council on ESD Targets has
released a white paper to JEDEC, in which they state that
“standard” processes will ensure 500V maximum of
ESD. This means that the chips can have their ESD
protection levels decreased. For “enhanced” processes,
the on-chip protection level can be decreased further.
E
S
D
As IC processes have
improved (e.g. 180 nm to
130 nm feature size) the
space required by the
functional circuits has
shrunk. But the space
required to maintain
current level of ESD
protection also stayed the
same.
Functional
die space
Processor, ASIC, etc.
CIRCUIT
PROTECTION
SOLUTIONS
E
S
D
2008
Manufacturers have improved their
processes such that on-chip protection
can be decreased and save die space.
They can maintain high yields and
reduce the ESD protection to 200V to
500V. Board developers will need to
take this into account during application
design.
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Industry Council on ESD Target Levels
• Recommendations from August 2007 White Paper
• http://www.esda.org/documents/WhitePaper1_HBM_MM_2007.pdf
CIRCUIT
PROTECTION
SOLUTIONS
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
ESD gap
CIRCUIT
PROTECTION
SOLUTIONS
– chipset capability vs application needs
• Application testing is becoming more severe – 8kV contact discharge and higher
• But the amount of ESD protection on the chipset is decreasing – 500V and below
Voltage level
During this time, no board-level
ESD devices were needed
ESD test level – driven by
electronics manufacturers
}
This “gap” represents a challenge in
protecting applications. Test levels
are increasing, but the capability of
the chipsets to survive ESD is
decreasing….
Robustness of chipsets – driven
by semiconductor manufacturers
Time
In order to ensure that applications
will suffer minimal field returns, ESD
suppression devices need to have
improved performance:
• Minimized turn-on voltage
• Minimized clamping voltage
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
How does this relate to ESD suppressors?
Each technology has a different response!
CIRCUIT
PROTECTION
SOLUTIONS
ESD pulse is 8kV, direct discharge, per IEC 61000-4-2
V5.5MLA0402 - response to ESD
(8kV, direct discharge)
250
200
Voltage (V)
150
100
V5.5MLA0402
50
0
-50
0
50
100
150
200
250
-50
Time (ns)
SP1001-05JTG (silicon)
Peak voltage = 150V
Clamp voltage = 10.0V
V5.5MLA0402 (ceramic, chip varistor)
Peak voltage = 180V
Clamp voltage = 12.0V
Notice that even though the two devices have the same operating voltage, their
response to ESD is different and can make a difference in the application.
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
How does this relate to ESD suppressors?
Each technology has a different response!
ESD pulse is 8kV, direct discharge, per IEC 61000-4-2
CIRCUIT
PROTECTION
SOLUTIONS
PGB1010603 - response to ESD
(8kV, direct discharge)
600
500
Voltage (V)
400
300
PGB1010603
200
100
0
-50
-100
0
50
100
150
200
250
Time (ns)
PGB1010603 (polymer suppressor)
Peak voltage = 554V
Clamp voltage = 60.4V
Capacitance = 0.05pF
SP3001-04 (silicon)
Peak voltage = 164V
Clamp voltage = 18V
Capacitance = 0.65pF
Conclusion:
As the processors in electronic applications become more sensitive to ESD, the peak and clamping
voltages of the board-level protection will need to be improved to ensure the reliable performance of
the end application (cell phone, set top box, LCD TV, etc.)
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
CIRCUIT
PROTECTION
SOLUTIONS
Increasing data rates in I/O circuits
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Data rate increases drive changes in protection
CIRCUIT
PROTECTION
SOLUTIONS
– Capacitance level of protection must be decreased
Changes in existing protocols
• USB 1.1
12Mbps
USB 2.0
480Mbps
• HDMI 1.1
1.6Gbps
HDMI 1.3
3.4Gbps
• 1394 S400
400Mbps
1394 S800
800Mbps
USB 3.0
5.0Gbps
1394 S1600
1.6Gbps
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Stray capacitance consideration
CIRCUIT
PROTECTION
SOLUTIONS
STRAY CAPACITANCE CONSIDERATION
It is important to make sure that the ESD suppressor does
not add too much capacitance to the circuit such that signal
degradation/distortion takes place.
Desired Digital Wave Shape
Voltage
As capacitance and data
rates increase, the amount
of distortion to leading and
trailing edges increases.
Eventually, distortion is
sufficient to interfere with
data transmission.
Distorted Wave Shape
Time
… this does not mean that suppressor capacitance is “bad”. In fact, capacitance of
the suppressor can act like a low band pass filter. The suppressor has the added
benefit of EMI noise filtering; this makes it ideal for protecting low speed data lines.
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Distortion increases with data rate increases
CIRCUIT
PROTECTION
SOLUTIONS
– Voltage versus time
Progression of data rate
speeds; with the same
suppressors (capacitance)
used in each chart.
Capacitance Key:
Littelfuse - V5.5MLA0603 - 660 pF
Industry Standard SMD Capacitor - 390 pF
Littelfuse - V18MLE0603 - 100 pF
Littelfuse - PGB0010603 - 0.05 pF
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Distortion increases with data rate increases
CIRCUIT
PROTECTION
SOLUTIONS
– Voltage versus time
Progression of data rate
speeds; with the same
suppressors (capacitance)
used in each chart.
Capacitance Key:
Littelfuse - V5.5MLA0603 - 660 pF
Industry Standard SMD Capacitor - 390 pF
Littelfuse - V18MLE0603 - 100 pF
Littelfuse - PGB0010603 - 0.05 pF
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Distortion increases with data rate increases
CIRCUIT
PROTECTION
SOLUTIONS
– Eye diagram data; USB 1.1 data rate of 12Mbps
PulseGuard (0.050 pF)
3 pF capacitor
“Failure” occurs if any
portion of the eye
diagram touches the
defined forbidden area
(i.e. the trace turns red).
MLE series (100 pF)
33 pF capacitor
Remember that these traces
only include the connector
saver board and suppressor
contributions. Actual
boards have additional stray
capacitance.
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Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Distortion increases with data rate increases
CIRCUIT
PROTECTION
SOLUTIONS
– Eye diagram data; USB 2.0 data rate of 480Mbps
PulseGuard (0.050 pF)
3 pF capacitor
“Failure” occurs if any
portion of the eye
diagram touches the
defined forbidden area
(i.e. the trace turns red).
MLE series (100 pF)
33 pF capacitor
Remember that these traces
only include the connector
saver board and suppressor
contributions. Actual
boards have additional stray
capacitance.
14
Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408
Distortion increases with data rate increases
– Eye diagram data; IEEE 1394 S800 data rate of 800Mbps
PulseGuard (0.050 pF)
CIRCUIT
PROTECTION
SOLUTIONS
3 pF capacitor
“Failure” occurs if any
portion of the eye
diagram touches the
defined forbidden area
(i.e. the trace turns red).
MLE series (100 pF)
33 pF capacitor
Remember that these traces
only include the connector
saver board and suppressor
contributions. Actual
boards have additional stray
capacitance.
15
Confidential and Proprietary to Littelfuse, Inc. ® Littelfuse, Inc. 2008. All rights reserved.
Modified_010408