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--- felinefriendly:bosch:b57678 [2018/07/27 18:27] – created e30tuner
+++ felinefriendly:bosch:b57678 [2018/07/27 22:40] (current) – [Description] e30tuner
@@ Line 4: / Line 4: @@
 This part was taken from a Motronic M1.7.3 engine control unit (ECU), which was commonly used on 1.6L & 1.8L 4-cylinder BMWs of the mid-E36 generation. While this chip was likely used on a number of ECUs, the specific one in this case had Bosch PN 0 261 203 661.
-This chip is believed to be a National Semiconductor LM2903 dual differential comparator. Functionally, it is used to detect fault conditions with the ignition coils. When the primary current to an ignition coil (basically, a high-ratio transformer) is switched off, a voltage spike is produced which the switching transistors clamp to ~400V. This spike is divided by resistors and fed to this comparator. If the spike is more than ~200V (in this implementation) it will cause the output of the comparator to latch high, until the ECU's MCU reads the signal and issues a reset pulse via the other comparator circuit.
+This chip is believed to be a National Semiconductor LM2903 dual differential comparator. Functionally, it is used to detect fault conditions with the ignition coils. When the primary current to an ignition coil (basically, a high-ratio transformer) is switched off, a voltage spike is produced which the switching transistors clamp to ~325V. This spike is divided by resistors and fed to this comparator. If the spike is more than ~200V (in this implementation) it will cause the output of the comparator to latch high, until the ECU's MCU reads the signal and issues a reset pulse via the other comparator circuit.
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