Fairchild Reference Design RD-576
Automotive Ignition Application
Evaluation Board
Ignition Application reference design for
device evaluation in test bench
Featured Fairchild Products:
FAN1100_F085
FGD3040G2_F085
Fairchild’s Automotive Conventional Vehicles Group
Direct questions or comments
about this evaluation board to:
“Worldwide Direct Support”
Fairchild Semiconductor.com
© 2016 Fairchild Semiconductor Corporation
RD-576 • Rev. 1.0
Table of Contents
1. Introduction ............................................................................................................................... 3
1.1.
1.2.
Devices description .......................................................................................................... 4
Devices features ............................................................................................................... 4
2. Evaluation Board Specifications ............................................................................................... 5
3. Photographs............................................................................................................................... 6
4. Printed Circuit Board ................................................................................................................ 7
5. Schematic .................................................................................................................................. 9
6. Bill of Materials ...................................................................................................................... 10
7. External devices assumptions ................................................................................................. 11
8. Production and use of the Evaluation Board........................................................................... 12
8.1.
8.2.
8.3.
8.4.
Production of the PCB.................................................................................................... 12
Suggested application circuit ......................................................................................... 12
Connection and supply of the evaluation board ............................................................. 13
Cautions and other considerations ................................................................................. 13
9. Test Equipment ....................................................................................................................... 14
10. Performance of the Evaluation Board ..................................................................................... 15
10.1.
10.2.
10.3.
Dwell and Current Limit............................................................................................. 15
Clamp.......................................................................................................................... 16
Max-dwell function and Soft Shutdown (SSD) .......................................................... 17
11. Conclusions ............................................................................................................................. 18
12. Related Resources ................................................................................................................... 19
© 2016 Fairchild Semiconductor Corporation
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This reference design supports the application evaluation board called Automotive Ignition
Application Evaluation Board. It should be used in conjunction with the device datasheets,
Fairchild’s application notes, and technical support team. It is highly recommended to have on
hand our application note AN-8208: Introduction to Automotive Ignition Systems.
Please consider that the present document and the evaluation board itself are meant to be a
reference design to support the customer during the first stages of design. The board has been
evaluated just under certain conditions and assumptions that differ to an automotive final
application.
Please visit Fairchild’s websites www.fairchildsemi.com and the Automotive Ignition webpage for
further product information.
1. Introduction
This document describes a proposed solution for an ignition Inductive Discharge Ignition (IDI)
System using our EcoSPARKTM Ignition IGBTs and the Ignition Driver IC FAN1100_F085. The
battery voltage range is from 6 V to 28 V (typical and recommended 12-14 V) and the input drive
signal is up to 6 V (recommended 5 V). The board is not fully automotive qualified and it has been
designed for evaluation purposes only.
One coil
two spark
Ignition
Coil
+
Automotive Ignition
Evaluation Board
Battery
IGBT
Driver
V1
Ignition
IGBT
Vcc
Z1
V2
+
Spark
plug
R1
ECU
Z2
R2
Figure 1.
Block diagram ignition application. IDI system
This document contains general description of the Evaluation Board and the featured devices, the
application specifications and boundary assumptions, schematic, bill of materials and the typical
operating characteristics.
© 2016 Fairchild Semiconductor Corporation
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1.1. Devices description
EcoSPARK® Ignition IGBTs are optimized to control the load current through the ignition coil
and feature an integrated clamp structure that limits the maximum voltage on the primary side. In
this evaluation board, the Ignition IGBT FGD3040G2_F085 is used as an example.
Our driver ICs are designed to directly drive the ignition IGBT and control the current and spark
event of the coil. The FAN1100_F085 is designed to directly drive an ignition IGBT and control
the current and spark event of the coil. The coil current is controlled via the input pin. When the
input is driven high, the output of the FAN1100_F085 is enabled to turn on the IGBT and start
charging the coil. The FAN1100_F085 will sink a current into the input pin based on programmed
current on the RA line.
An input spike filter suppresses input signals of less than 13 µsec in duration. A Max Dwell timer
is included in the FAN1100_F085 which will turn off the IGBT if the input stays active for longer
than the programmed time. This time interval can be modified through an external capacitor on the
CSSD pin. When the Max Dwell timer is exceeded, the FAN1100_F085 will enter a Soft-ShutDown mode (SSD) slowly dropping the collector current by lowering the gate drive to the IGBT
thereby discharging the coil such as to inhibit a spark event. Once the soft shutdown operation has
started, any transitions on the input signal are ignored until after completion of the soft shut down
function. The FAN1100_F085 will also limit the collector current of the IGBT to Ic(lim) during
charging. This again is done through the sense resistor in the emitter leg of the Ignition IGBT
developing a signal input to the Vsense pin of the FAN1100_F085.
1.2. Devices features
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


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


SCIS Energy = 300 mJ at TJ = 25°C for the FGD3040G2_F085
Logic Level Gate Drive at the IGBT gate
Automotive qualified and RoHS Compliant
Signal Line Input Buffer and Input spike filter
Programmable maximum dwell time
Programmable Input Pull down current
Control IGBT current limiting through Vsense pin
Soft Shutdown following Max Dwell Time out
© 2016 Fairchild Semiconductor Corporation
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2. Evaluation Board Specifications
All data for this table was measured at an ambient temperature of 25°C.
Table 1.
Summary of features and performance
Description
Input Voltage
Symbol
Value
VIN, min, VIN, nom,
VIN,max
Comments
Refer to FAN1100_F085 datasheet
Input Frequency
freqIN,max
200 Hz
Collector Current
ICtyp
12 A
Current limit
Ilim
Based on selection of Rsense
Max-Dwell
TMAX
Based on selection of Cssd
SSD Slew Rate
Islew
1.5 A/ms
Typical slew rate
TFANxxx
< 150°C
TIGBT
< 175°C
At full load (all at open frame, room
temperature / still air)
Temperature
Application
© 2016 Fairchild Semiconductor Corporation
Typical 5-60 Hz
Typical collector current
Ignition system
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3. Photographs
Figure 2.
© 2016 Fairchild Semiconductor Corporation
Evaluation board. (Photograph top view)
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4. Printed Circuit Board
Figure 3.
Top view PCB layout including TOP and BOT layers (not real size)
Figure 4.
© 2016 Fairchild Semiconductor Corporation
Top view PCB layout. TOP layer (not real size)
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Figure 5.
© 2016 Fairchild Semiconductor Corporation
Top view PCB layout. BOT layer (not real size)
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5. Schematic
Figure 6.
© 2016 Fairchild Semiconductor Corporation
Evaluation Board Schematic
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6. Bill of Materials
Table 2.
Bill of materials
Reference
Qty
Part Number
Value
Description
Manufacturer
Cbat1
1
SMD - 0805
0.47 µF
Supply filter
-
Rbat
1
SMD - 1210
300 Ω
Supply filter
-
Cbat2
1
SMD - 0805
0.1 µF
Supply filter
-
Cinc
2
SMD - 0805
No populate
-
Rin
1
SMD - 1210
No populate
-
Cin/Cind
1
SMD - 0805
10 nF
Input signal filter
-
RA
1
SMD - 0805
15 kΩ
Input Current
Reference Resistor
-
RB
1
SMD - 1210
51 Ω
Input Buffer Resistor
-
CIGF
1
-
No populate
-
Jumpers
6
Cssd
1
SMD - 0805
FAN1100
1
Ignition IGBT
1
Rsense
1
TP
11
Connector
1
Soft shutdown
-
FAN1100_F085
IGBT Driver IC
Fairchild
FGD3040G2_F085
Ignition IGBT
Fairchild
Current sense
-
© 2016 Fairchild Semiconductor Corporation
10 nF
20 mΩ
Test point
-
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7. External devices assumptions
Table 3.
Reference
Qty
Ignition Coil
1
Spark Plug
1
External BOM
Description
The coil primary winding inductance is approximately 3.6 mH
The resistance of primary winding is approximately 0.6 ohm
The capacitance is approximately 25 pF
Figure 7.
Test circuit setup scheme
Figure 8.
© 2016 Fairchild Semiconductor Corporation
Test circuit setup
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8. Production and use of the Evaluation Board
8.1. Production of the PCB
These are the PCB characteristics of the evaluation board we have built:
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


3.8 by 2.5 Inch, 2 Layer Board
Solder Mask on Top and Bottom
Silkscreen on Top
Laminate: FR-4 with a Dielectric Constant between 4.2 to 5
Copper Thickness: ~0.0017 inches
8.2. Suggested application circuit
One coil
two spark
Ignition
Coil
Battery or
Battery
Simulator
Demo
Board
-
+
Cbat1
Pin 1 Collector V1
-
Pin 2 Vbat
Rbat
V2
+
Ignition
IGBT
Cbat2
Signal current
measurement Pin 3 INPUT/INH
Primary current
measurement
Z1
Spark
plug
RB
R1
Vce
measurement
Cin
ECU or Signal
Generator
Vin
measurement
Pin 4 INL
IGBT
Driver
Figure 9.
© 2016 Fairchild Semiconductor Corporation
Z2
R2
Cssd
RA
Pin 6 Gnd
Application circuit setup
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8.3. Connection and supply of the evaluation board
For a safe installation of the test setup, we recommend to follow the next steps:
 Connect the primary return wire form the Ignition Coil to “Pin 1 Collector” of the Ignition
Driver Evaluation Board.
 Connect the positive terminal of the battery or battery simulator to “Pin 2 Vbat”.
 Connect the positive terminal of a signal generator to “Pin 3 INPUT/INH”.
 Connect the negative terminal of a signal generator to “Pin 4 INL”.
 Connect the negative terminal of the battery or battery simulator to “”.
 Connect the primary power of the ignition coil to the positive terminal of the battery or
battery simulator.
 Connect the coil to the sparkplug.
 Connect the ground of the sparkplug to the ground of the negative terminal of the battery or
battery simulator.
 Insert the FAN1100_F085 into the socket and firmly close the socket.
 Configure the signal generator parameters, such as voltage levels, duty ratio and frequency,
as specified in Section 2.
8.4. Cautions and other considerations
We assume that you have a decent and safe lab to work in. Please consider that we work here
with high voltages and currents and an improper or unsafe use could be lethal. Prepare, check
and calibrate the equipment and review that cables, connectors and scopes are in good state.
Clean the desk and safety shields. Test circuit breakers and emergency circuits.




Fuse suggested to be placed on the battery line for protection and safety.
The wire connecting the collector of the IGBT and the primary return of the coil is
recommended to have greater than 800 V insulation.
The spark plug should be grounded, otherwise undesired arcing over may occur.
Recommend to power down the board before replacing any components.
© 2016 Fairchild Semiconductor Corporation
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9. Test Equipment
Table 4.
Test Equipment
Battery Simulator
Pulse Generator: DG4162 by RIGOL
Oscilloscope: 610Zi by LeCroy
Test Equipment
Current Probe: AP015 by LeCroy
High Voltage Probe: PPE4KV by LeCroy
Voltage Probe: PP005A by LeCroy
Pearson coil for low current measurement
© 2016 Fairchild Semiconductor Corporation
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10. Performance of the Evaluation Board
Please study carefully the application note, AN-8208, to understand all the details of the ignition
system behavior shown below.
10.1. Dwell and Current Limit
After a certain dwell time, an increase in the dwell time will not affect the peak primary current,
as the device gets into current limit.
Figure 10. Dwell time and current limit
© 2016 Fairchild Semiconductor Corporation
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10.2. Clamp
To initiate the sparking event, the device turns off the current rapidly. The energy in leakage
inductance causes the voltage to rise to the voltage clamp of the IGBT.
Figure 11. Clamping period after dwell time
© 2016 Fairchild Semiconductor Corporation
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10.3. Max-dwell function and Soft Shutdown (SSD)
Adjust the pulse width for a time longer than max dwell time associated with the selected CSSD
capacitor. Once the device enters SSD after the max dwell time, any change in the signal will not
be noticed on the output until the current is fully discharged. CSSD Vs Time can be found in the
FAN1100_F085 datasheet.
Figure 12. Max dwell and soft shutdown
© 2016 Fairchild Semiconductor Corporation
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11. Conclusions
In RD-576, the evaluation board for an ignition application has been presented. Schematics and layout
have been shown and some relevant test results have been shared. The test setup has been suggested and
some safety advices have been given. This information must be sufficient for an experienced electronic
system designer to set the evaluation running. With help of the devices datasheets and the application note
AN-8208, a designer can even fine tune the circuitry according to his needs and that could be a very good
initial point for the design of the final application.
Please consider that the present document and the evaluation board itself are meant to be a reference
design to support the customer during the first stages of design. The board has been evaluated just under
certain conditions and assumptions that differ to an automotive final application.
© 2016 Fairchild Semiconductor Corporation
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RD-576 • Rev. 1.0
12. Related Resources
AN-8208 Introduction to Automotive Ignition Systems
FAN1100_F085 Product Page
FGD3040G2_F085 Product Page
Automotive Ignition Webpage
Authors:
Jose Padilla – Product Marketing Manager
Qingquan Tang – Applications Engineer
Mitchell Henry – Applications Engineer
Reference Design Disclaimer
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© 2016 Fairchild Semiconductor Corporation
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