ESD immunity-level optimization of a high-side switch
Introduction
AN3107
Application note
application based on the VNI4140K
The VNI4140K is a quad-channel high-side driver designed for industrial applications. It is
a monolithic device manufactured using STMicroelectronics’ most advanced VIPower
technology, intended for driving four independent resistive or inductive loads with one side
connected to ground. The device fully complies with standards including JEDEC (JESD22)
and IEC 61131-2. It conforms to the “human body model” ESD test in accordance with the
JESD22-A114 definition. The immunity level is 2000 V, as stated in the datasheet of the
device.
When the VNI4140K is mounted in the complete application, the system must meet
minimum requirements defined by generic standard IEC 61000-4-2. However, the actual
immunity level depends on the manufacturer of the final application. To achieve the required
level of immunity, the device must be equipped with a suitable application environment,
external components and/or a suitable PCB layout.
This application note provides some recommendations on how to optimize the ESD
immunity level of the VNI4140K high-side switch application in accordance with the IEC
61000-4-2 standard.
Figure 1. VNI4140K ESD optimized PCB example
®
March 2010 Doc ID 16783 Rev 1 1/17
www.st.com
Contents AN3107
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Test setup according to IEC 61000-4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Test conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Classification of the test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Application solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Cap filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Π filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3 Dual LC filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2/17 Doc ID 16783 Rev 1
AN3107 List of tables
List of tables
Table 1. Application immunity with C filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 2. Application immunity with Π filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 3. Application immunity with dual LC filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 4. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Doc ID 16783 Rev 1 3/17
List of figures AN3107
List of figures
Figure 1. VNI4140K ESD optimized PCB example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 2. ESD test setup according to IEC 61000-4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3. Application schematic diagram with capacitive filter protection . . . . . . . . . . . . . . . . . . . . . . 7
Figure 4. Example of a spiral PCB inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 5. Midi Spring inductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 6. Application schematic diagram with Π filter protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 7. Application schematic diagram with dual LC filter protection . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 8. Test board views. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4/17 Doc ID 16783 Rev 1
AN3107 Test setup according to IEC 61000-4-2
2 Test setup according to IEC 61000-4-2
The IEC 61000-4-2 standard provides the test procedure for various types of applications.
The test setup for ungrounded (tabletop) equipment is selected. The structure is shown in
Figure 2.
Figure 2. ESD test setup according to IEC 61000-4-2
2.1 Test conditions
● Supply voltage: 24 VDC, always ON
● Inputs OFF, outputs OFF
● Air discharge
● Polarity: positive/negative
● Discharge unit: 150 pF / 330 Ω
● Applied to: board output terminal
2.2 Classification of the test
A - normal performance
B - temporary degradation or loss of function or performance, with automatic return to
normal operation
C - temporary degradation or loss of function which requires external intervention to recover
normal operation
D - degradation or loss of function, need substitution of damaged components to recover
normal operation.
Doc ID 16783 Rev 1 5/17
Application solutions AN3107
3 Application solutions
Ideas (application environment) on how to optimize the immunity of the device are listed in
Section 3.1, Section 3 .2 and Section 3.3.
3.1 Cap filters
This basic configuration uses 22 nF ceramic capacitors connected between the device
outputs and ground. It protects the VNI4140K primarily against radio-frequency and fast
transient disturbances.
6/17 Doc ID 16783 Rev 1
AN3107 Application solutions
Figure 3. Application schematic diagram with capacitive filter protection
Doc ID 16783 Rev 1 7/17
Application solutions AN3107
With this basic configuration, application immunity is limited in the case of a negative ESD
pulse of -8 kV (air discharge), as listed in Tabl e 1.
Table 1. Application immunity with C filters
Test signal level
3.2 Π filters
Improved results are achieved when using Π LC filters at the VNI4140K outputs.
Measurements show the best results with 22 nF ceramic capacitors and approximately 82
nH inductors. The inductor can be implemented either as a “spiral” directly on the PCB
substrate, or placed as a discrete component.
If, based on available space, the inductor is implemented as a “spiral” directly on the PCB
substrate, the cost of a discrete conductor is saved. An example is shown in Figure 4.
The discrete inductor should be a wire-wound, air-core type if possible. Ferrite-based
inductors did not produce positive results. An example of a suitable component is the
1812SMS-82NJLB, Midi Spring
Polarity / result criteria
[kV]
2BB
4BB
6BB
8BD
10 B D
12 B D
®
Air Core inductor from Coilcraft.
+–
Figure 4. Example of a spiral PCB inductor
8/17 Doc ID 16783 Rev 1
AN3107 Application solutions
Figure 5. Midi Spring inductors
Doc ID 16783 Rev 1 9/17
Application solutions AN3107
Figure 6. Application schematic diagram with Π filter protection
/54
/54
/54
4! "
10/17 Doc ID 16783 Rev 1
AN3107 Application solutions
The results in Table 2 are achieved employing Π LC filters. This configuration appears to be
a satisfactory compromise between the PCB space occupied, component cost and
application immunity, which is notably improved. In this case, the application withstands air
discharges up to -14 kV without silicon degradation or damage (using the Midi Spring
inductors).
Table 2. Application immunity with Π filters
Polarity / result criteria
(1)
Test signal level [kV]
8BB
10 B B
12 B B
14 B B / D
15 B D
16 B —
1. The results shown are based on testing with Midi Spring inductors.
2. Based on testing with PCB inductors.
3.3 Dual LC filters
The best performance is achieved using dual (cascade) LC filters. The schematic diagram
and test results are provided in Figure 7 and Tabl e 3.
Π (LC) filter
+–
(2)
Doc ID 16783 Rev 1 11/17
Application solutions AN3107
Figure 7. Application schematic diagram with dual LC filter protection
12/17 Doc ID 16783 Rev 1
AN3107 Application solutions
Figure 8. Test board views
Table 3. Application immunity with dual LC filters
Test signal level [kV]
+—
8BB
10 B B
12 B B
14 B B
15 B B
16 B D
1. Tests performed with “spiral” PCB inductors.
An increase in immunity of approximately 3 kV can be observed compared to the Π filter
configuration (with PCB inductor). Whether or not to use the dual filter is based on
application requirements.
Polarity / result criteria
(1)
Doc ID 16783 Rev 1 13/17
Conclusion AN3107
4 Conclusion
The VNI4140K application is immune to the positive polarity of the ESD at a voltage level
higher than 16 kV.
In the case of negative pulse immunity, special attention should be paid to the output filter,
which slows down the ESD pulse. Three configurations have been tested.
The dual LC filter (cascade connection) structure is highly immune but requires more space
on the PCB. A level of -15 kV without silicon degradation was achieved.
The configuration using Π filters provides a good compromise between the immunity and
PCB space in this implementation. A level of -14 kV (using Midi Spring inductors) / -12 kV
(PCB inductors) without silicon degradation was achieved.
The basic device connection with a single ceramic capacitor at each output provides
robustness against -6 kV ESD pulses.
14/17 Doc ID 16783 Rev 1
AN3107 References
5 References
1. VNI4140K device datasheet
2. AN2684 - STEVAL-IFP006V1: designing with VNI4140K quad high-side smart power
solid-state relay ICs
3. AN2208 - Designing Industrial Applications with VN808/VN340SP High-side Drivers
4. AN1351 - VIPower AND BCDmultipower: making life easier with ST's high side drivers
5. IEC61000-4-2 Electrostatic discharge
Doc ID 16783 Rev 1 15/17
Revision history AN3107
6 Revision history
Table 4. Document revision history
Date Revision Changes
24-Mar-2010 1 Initial release.
16/17 Doc ID 16783 Rev 1
AN3107
y
Please Read Carefully:
Informatio n in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the
right to make changes, corrections, modifications or improvements, to this document, and the products an d services described herein at an
time, without notice.
All ST products are sold pursuant to ST’s terms and conditions of sale.
Purchasers are sole ly responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no
liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this
document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products
or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such
third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT
RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING
APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY,
DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE
GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void
any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any
liability of ST.
ST and the ST logo a re trademarks or registered trademarks of ST in various countries.
Information in this docume nt supersedes and replaces all information previously supplied.
The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.
© 2010 STMicroelectronics - All rights reserved
STMicroelectronics group of companies
Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israe l - Italy - Japan -
Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America
www.st.com
Doc ID 16783 Rev 1 17/17
Loading...