External ESD Protection of LIN transceiver DownloadLink 4004

Application note TH808x
External ESD protection
Application Hints for using external ESD protection of
TH808x
TH808x
1.
Scope
This application note describes the possibility to increase the ESD robustness level of
TH8080x by using different external protection elements.
To verify different external circuitries it was applied the standard LIN ESD test method
described in the LIN EMC Test Specification Rev. 2.0 (DIN 61000-4-2). This test method is
used for the IC related ESD verification of LIN devices.
The value of this test method can correlate with the behaviour on module level, but in
general the test conditions, pulse forms, rise times and the energy of the applied pulses
are much different.
Fig.1 shows the improvement of the ESD protection on TH808x by using different ESD
protection elements.
15 KV
14 KV
13 KV
12 KV
11 KV
10 KV
9 KV
8 KV
applicable
7 KV
6 KV
5 KV
applicable
4 KV
3 KV
2 KV
applicable
1 KV
0 KV
without ESD protection
ESD protection with
varistor
ESD protection with Peak
Power Zener Transient
Voltage Suppressors
diode
Figure 1 – Results of ESD test of Th808x with different external ESD protection elements
Appl.Note – External ESD Protection
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Application note TH808x
External ESD protection
2.
Description of the ESD test according to DIN 6100061000-4-2
For the test according to DIN 61000-4-2 was used the following equipment:
ESD simulator
Discharge module
Oscilloscope
Function generator
EM Test ESD 30C
P 30C (150pF/ 330Ω, 150pF/2000Ω or 330pF/2000Ω)
Tektronix TDS 544A
HAMEG HM8130
Fig.2 shows the schematic of the ESD test setup and Fig.3 shows the test PCB.
Figure 2 - Schematic of the ESD test setup
Figure 3 - ESD test PCB TH808x
Appl.Note – External ESD Protection
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Application note TH808x
External ESD protection
3.
Test Results
In order to check to the device after applying the ESD stress it was monitored the pin I/V
characteristics. With this pin characteristic measurement is it is possible to detect already
a pre-damaging caused by ESD, also if the IC functional is still OK.
3.1 ESD protection using Varistor (TDK AVR-M1608C270MBABB 15pF), bus
capacitor 180pF (Slave Module) and resistor 10Ω ESD protection using varistor
Protection elements:
Varistor:
Bus Capacitor:
Bus serial Element:
TDK AVR-M1608C270MBABB (15pF)
180pF (slave module)
10 Ω
TH8082
Resistor
LIN
Bus
10Ohm
180p
Varistor
Figure 4 - Schematic of the ESD protection with varistor
The damage limit by using varistor and serial resistor as protection elements is 9 to 15kV.
The result is sufficient for a robustness level of 8kV.
ESD- Measurement: LIN- Bus, I/V characteristics
Transceiver:
TH8082 KDC 0352
Pin:
LIN to GND
Bus capacitor:
180pF / 10 Ohm plus Varistor
Pin Current [mA]
1,2
1,0
0,8
0,6
0,4
0,2
0,0
-0,2
-0,4
-0,6
-0,8
-1,0
-1,2
-40
-30
Before test
# 3 @ +6kV
# 3 @ -6kV
# 3 @ +7kV
# 3 @ -7kV
# 3 @ +8kV
# 3 @ -8kV
# 3 @ +10kV
# 3 @ -10kV
# 3 @ +12kV
-20
-10
0
10
20
30
40
50
60
Pin Voltage [V]
Figure 5 - I/V pin characteristic after applying different ESD pulses
Appl.Note – External ESD Protection
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Application note TH808x
External ESD protection
3.2 ESD protection using Back-to-Back Zener Diode (Onsemi MMB27VCLT1 30pF),
bus capacitor 180pF (Slave Module) and resistor 10Ω
Protection elements:
Diode:
Bus Capacitor:
Bus serial Element:
ON-Semi MMBZ27VCLT1 (30pF)
180pF (slave module)
10 Ω
TH8082
Resistor
LIN
Bus
10Ohm
180p
MMBZ27VCLT1
Figure 6 - Schematic of the ESD protection with Back-to-Back Zener Diode
The damage limit by using Back-to-back zener diode and serial resistor as protection
elements is >15kV.
The result is sufficient for a robustness level of 15kV.
ESD- Measurement: LIN- Bus, I/V characteristics
Transceiver:
TH8082 KDC 0352
Pin:
LIN to GND
Bus capacitor:
Pin Current [mA]
1,2
1,0
0,8
0,6
0,4
0,2
0,0
-0,2
-0,4
-0,6
-0,8
-1,0
-1,2
-40
-30
180pF / 10 Ohm plus Peak Power Zener Transient Voltage Suppressors diode
Before test
# 3 @ +6kV
# 3 @ -6kV
# 3 @ +8kV
# 3 @ -8kV
# 3 @ +12kV
# 3 @ -12kV
# 3 @ +15kV
# 3 @ -15kV
-20
-10
0
10
20
30
40
50
60
Pin Voltage [V]
Figure 7 - I/V pin characteristic after applying different ESD pulses
Appl.Note – External ESD Protection
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Application note TH808x
External ESD protection
3.3 ESD protection using Back-to-Back Zener Diode (Onsemi MMB27VCLT1 30pF),
bus capacitor 1nF (Master Module) and SMD-ferrite (Würth: 742 792 097)
Protection elements:
Diode:
Bus Capacitor:
Bus serial Element:
ON-Semi MMBZ27VCLT1 (30pF)
1nF (master module)
SMD-ferrite Würth 742 792 097
TH8082
SMD-Ferrite
LIN
Bus
742 793 097
1n
MMBZ27VCLT1
Figure 8 - Schematic of the ESD protection with Back-to-Back Zener Diode
The damage limit by using Back-to-back zener diode and serial SMD-ferrite as protection
elements is >15kV.
The result is sufficient for a robustness level of 15kV.
ESD- Measurement: LIN- Bus, I/V characteristics
Transceiver:
TH8082 KDC 0642
Pin:
LIN to GND
Bus capacitor:
1nF & MMBZ27VCLT1 to GND; Ferrite (Würth: 742 792 097) in line
Pin Current [mA]
1,2
1,0
0,8
0,6
0,4
0,2
0,0
-0,2
-0,4
-0,6
-0,8
-1,0
-1,2
-40
-30
Before test LIN
# LIN @ +4kV
# LIN @ -4kV
# LIN @ +8kV
# LIN @ -8kV
# LIN @ +15kV
# LIN @ -15kV
-20
-10
0
10
20
30
40
50
60
Pin Voltage [V]
Figure 9 - I/V pin characteristic after applying different ESD pulses
Appl.Note – External ESD Protection
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Application note TH808x
External ESD protection
3.4 ESD protection using Back-to-Back Zener Diode (Onsemi MMB27VCLT1 30pF),
bus capacitor 2,7nF (Master Module) and SMD-ferrite (Würth: 742 792 097)
Protection elements:
Diode:
Bus Capacitor:
Bus serial Element:
ON-Semi MMBZ27VCLT1 (30pF)
2,7nF (master module)
SMD-ferrite Würth 742 792 097
TH8082
SMD-Ferrite
LIN
Bus
742 793 097
2,7n
MMBZ27VCLT1
Figure 10 - Schematic of the ESD protection with Back-to-Back Zener Diode
The damage limit by using Back-to-back zener diode and serial SMD-ferrite as protection
elements is >15kV.
The result is sufficient for a robustness level of 15kV.
ESD- Measurement: LIN- Bus, I/V characteristics
Transceiver:
TH8082 KDC 0642
Pin:
LIN to GND
Bus capacitor:
2,7nF & MMBZ27VCLT1 to GND; Ferrite (Würth: 742 792 097) in line
Pin Current [mA]
1,2
1,0
0,8
0,6
0,4
0,2
0,0
-0,2
-0,4
-0,6
-0,8
-1,0
-1,2
-40
-30
Before test LIN
# LIN @ +4kV
# LIN @ -4kV
# LIN @ +8kV
# LIN @ -8kV
# LIN @ +15kV
# LIN @ -15kV
-20
-10
0
10
20
30
40
50
60
Pin Voltage [V]
Figure 11 - I/V pin characteristic after applying different ESD pulses
Appl.Note – External ESD Protection
390110808001
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July 2007
Rev 003
Application note TH808x
External ESD protection
4.
Summary
The recommended protection elements for the TH8080/82 LIN transceiver in order to
guarantee an ESD robustness level of 8kV at module level is:
Transceiver with external protection element varistor TDK AVR-M1608C270MBABB
(15pF) or similar, 180pF Bus capacitor and 10Ω series resistor.
In order to confirm the results and to check the influence of the external protection circuitry
regarding the EMC behaviour (DPI and emission), the test was done by IBEE, please see
EMC Test report Nr. 01-05-05 and 02-05-05.
External protection devices can decrease the EMC performance due to additional
resonances, clamping and demodulation effects! Both devices show an excellent EMC
behaviour with the recommended circuitry.
In applications with higher requirements to the ESD severity level (15kV pass), the
varistor can be replaced by an MMB27VCLT1 (On semiconductor Peak Power Zener
Transient Voltage Suppressor diode), or similar device.
In some cases the 10Ω series resistor is not approved to ESD protection. In this case the
10Ω series resistor can be replaced by an SMD ferrite, for instance an 1800Ω@100MHz
SMD ferrite (Würth: 742 792 097) with the same package.
Appl.Note – External ESD Protection
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July 2007
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Application note TH808x
External ESD protection
Disclaimer
Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its
Term of Sale. Melexis makes no warranty, express, statutory, implied, or by description regarding the
information set forth herein or regarding the freedom of the described devices from patent infringement.
Melexis reserves the right to change specifications and prices at any time and without notice. Therefore,
prior to designing this product into a system, it is necessary to check with Melexis for current information.
This product is intended for use in normal commercial applications. Applications requiring extended
temperature range, unusual environmental requirements, or high reliability applications, such as military,
medical life-support or life-sustaining equipment are specifically not recommended without additional
processing by Melexis for each application.
The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not be
liable to recipient or any third party for any damages, including but not limited to personal injury, property
damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or consequential
damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical
data herein. No obligation or liability to recipient or any third party shall arise or flow out of Melexis’ rendering
of technical or other services.
© 2002 Melexis NV. All rights reserved.
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QS9000, VDA6.1 and ISO14001 Certified
Appl.Note – External ESD Protection
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July 2007
Rev 003