4-Channel Ignition/Injection Driver Board


bare v1.0 board

With the introduction of the new MS2/extra sequential code which has the capability to have 4 injection channels, there is a need to modify the MS2 daughter card (as described here) and add injector drivers to take advantage of this new feature. The 4-Channel Ignition/Injection Driver Board combines the 4 injector drivers with 4 ignition drivers and a DB15 connector to clean up the wiring within the MS case and ease the wiring outside the case with a connector dedicated to the high current devices. There is also the advantage of completely isolating these high current devices from the main MegaSquirt board to reduce electrical noise to a minumum.

The 4-Channel Ignition/Injection Driver Board can be used for any engine with 1 to 4 cylinders in full sequential mode with one injector and coil per driver, and with 6 and 8 cylinder engines in semi sequential mode and wasted spark with 2 injectors per driver and one coil per driver. The MS case is used as a heat sink for the IGBTs.

The board can also be used with any MS2/Extra code version for anyone wanting to use up to 4 ignition drivers and a connector for these drivers. The injector driver pins could then be used for other purposes

The injector drivers can be any suitable logic level FET in a DPAK package such as the specialized VND5N07 used in the MicroSquirt or other more generic FETs. The injector drivers are used with high impedance injectors only (or with low impedance injectors with inline resistors) and each driver has it's own dedicated pin on the DB15 connector and uses the 3 common ground pins. The board can be used with low impedance injectors in conjunction with the Peak&Hold Injector Driver Board by wiring the high current injector signals and grounds directly to the DB15 connector solder cups.

The ignition drivers can be any suitable logic level IGBT in a TO220 package such as the BIP373 or other ignition IGBTs. Each IGBT has 2 dedicated pins on the DB15 and they use the 3 common ground pins. The DB15 pins are rated at 5A continuous (10A for each ignition driver) and the board traces are sized accordingly (0.1"/2.54mm wide). Therefore, the board should be able to handle most coils since even if the peak current is higher than 10A since the average current will be much lower than the peak. The common ground pins are also sufficient since the coils are fired sequentially.

V1.1 board

There is an updated version of the board that keeps the same feature as the original one but adds the possibility of using the board with logic level ignition coils. This uses the TC4427-based circuit recommended in the MS2 and MS3 manuals which can drive any of the different types of logic-level coils.

bare v1.1 board

The V1.1 board is shown above with the two TC4427-based circuits that can drive 4 ignition channels (more than one ignition coil can be driven per channel). Note that the circuits use surface mount chips but these can still be soldered by hand relatively easily. Make sure that you can handle that before ordering.


The assembly is simply a question of soldering all the components to the board except the IGBTs (R1 to R8 are 330 Ohm or 1k Ohm resistors depending on the components used in the kit and R9 to R12 are 100K resistors). These will need to be soldered with the board in the top slot of the case, with the DB15 attached to the end plate, and with the end plate attached to the case top half. The IGBTs leads are inserted in the correct position from under the board with the leads bent 90 degrees upward.

Mounting holes are drilled in the case using, as template, the IGBTs in their place (but not soldered) in the board and with the board correctly positioned with the DB15 attached to the end plate. Once the holes are drilled, the board is installed with the IGBTs and the IGBTs are mounted using the mounting kits. Then the IGBTs are soldered to the board. The board should then be removed and cleaned before being installed permanently.

This completes the assembly.

Logic-level ignition drivers (V1.1 board)

If logic-level ignition drivers are used instead of the IGBT-based high current ignition drivers, skip the installation of the IGBTs and the R1 to R4 resistors in the instructions above; the mounting holes are also not needed.

Install the two TC4427 chips. Makes sure to use the correct orientation: the dot on the board silkscreen indicates pin 1 on the chip and there is a dimple on the chip that also indicates pin 1 (other versions of the chip might indicate pin 1 by having a bevel on the chip top on the pin 1 side). Install R13 to R16.

Please note that you can use only one type of driver on the board. The inputs and outputs are shared between the two circuits so there would be conflicts


The installation consist in connecting the board to the appropriate places on the MS board. The ground pad (right of the 4 injector driver pads) needs to be connected to a ground pad on the MS board (the proto area ground ca be used for this) and is only needed if using the on-board injector drivers. The 4 ignition driver pads need to be connected to the MS board as specified in the MS2/Extra manual. The 4 injector driver pads need to be connected to the MS board as shown in the MS2/Extra Sequential code page for the V3.0 board or the V2.2 board.

For IGBT-based high current drivers, the 5V and ground pads above the ignition driver pads on the V1.1 board are ignored.

The DB15 pins are assigned as shown in the picture below. This picture represents the DB15 as seen when looking at the MS end plate and assumes that the DB15 on the board is a male connector. Please note that the board top is on the side of pins 9 to 15 and is therefore facing down on the picture (as it will be when installed in the MS case).

DB15 Connections

Logic-level ignition drivers (V1.1 board)

You will need to provide 5V to the board to trigger the coils; this usually comes from the MegaSquirt 5V supply. You will also need to provide ground which also usually comes from the MegaSquirt board. You can use an external ground by soldering a jumper between the ground pad and the unidentified pad just to the right; this will connect the drivers ground to the DB15 ground pins.

The same DB15 pins are used for logic-level ignition drivers as what is pictured above. However due to the low current needs in this application, a single connector pin per ignition channel is sufficient and the second pin can be ignored.


The boards are available for US$18 per board plus shipping. Please note that this is for a bare board. Shipping for up to 4 boards is US$4.50 in North America and US$7.50 in the rest of the world. This is for regular mail shipping from Canada which means there is no insurance and no guarantee on the delivery time.
Please note that regular mail service to the US has been quite irregular. The delivery time has been from less than 2 weeks to more than 4 weeks. If this is not acceptable, you can request Xpresspost service which will speed up delivery but will cost an additional US$12. Contact me for details and price.

New! Complete and partial kits are now available. With the V1.1 board, the complete kit is available with high current ignition drivers or logic-level ignition drivers. The complete kit includes all the components needed to complete the assembly: 4 high current ignition drivers (IGBT+resistor+mounting hardware) OR 4 logic-level ignition drivers (2 TC4427+resistors), 4 injector drivers (FET+resistors), 2 DB15 connectors (one board-side male connector+hardware, one harness-side female connector+shell and hardware). The partial kit includes the board and the connectors. The ignition and injector drivers are available separately for those who don't need all the drivers and can be purchased with either the bare board or the partial kit. Please note that the shipping cost is for a single kit or partial kit.

Note: You will need thermal grease and wires to complete the installation (not included in complete kit).

Important: Please note that I do not sell ignition drivers or injection drivers without the purchase of a 4-channel driver board. If the order does not include a board, it will be canceled and refunded without further notice. I also reserve the right to limit the number of drivers to 4 ignition drivers and 4 injection drivers per board.

Kits are not available and there are currently no plans to have them back. Only the bare board is available.

                        4-Channel Ignition/Injection Driver Board V1.1
with No components (bare board) $18 shipped

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You can contact me through PM at the msextra forum where my user name is racingmini_mtl
or by email: boards at jbperf.com