Timeline for Are 24/12 V automotive ECUs 3.3 V under the hood?
Current License: CC BY-SA 4.0
17 events
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| Dec 7, 2023 at 16:34 | history | edited | Max F | CC BY-SA 4.0 |
Modify edit to remove introduced typo
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| Dec 7, 2023 at 16:32 | vote | accept | Max F | ||
| Dec 5, 2023 at 22:03 | comment | added | hacktastical | Cars don’t operate at ‘12V’. The lead-acid state of charge varies and can range between 11 and 14V or so. Also, when the alternator runs this adds noise to the battery rail. | |
| Dec 5, 2023 at 17:55 | answer | added | hacktastical | timeline score: 2 | |
| Dec 5, 2023 at 17:52 | history | edited | JRE | CC BY-SA 4.0 |
added 1 character in body; edited title
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| Dec 5, 2023 at 17:52 | comment | added | Max F | @Puffafish Cars as a whole may not operate at 12 V, but that is a common voltage level for valves, pumps, etc. supplied by Tier I & II suppliers. It's typically achieved using a DC/DC converter. For context, I'm working on electric vehicles so there are many bus voltages present. | |
| Dec 5, 2023 at 17:50 | comment | added | Max F | @Justme Thanks for laying it out. I understand that it's not possible to know the internals, I'm asking generally about automotive ECUs and provided this one as an example (as indicated in the original post) since they have a block diagram. | |
| Dec 5, 2023 at 17:49 | comment | added | Max F | @Colin Thanks for the additional info. I've edited my question to include some further details. I'm just interested in the internals and if Automotive ECUs typically run at 3.3 V internally, not the sensor supplies. | |
| Dec 5, 2023 at 17:48 | comment | added | Max F | @TimWilliams Thank you, that answers it fine. I'm looking for some reference designs if you know of any. If you respond with an answer, I will mark is as correct. | |
| Dec 5, 2023 at 17:45 | history | edited | Max F | CC BY-SA 4.0 |
Added clarification that I'm only interested in the internals of the ECU, added diagram showing application.
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| Dec 5, 2023 at 17:43 | comment | added | Justme | We can't know how this specific device or similar devices work. It might use 3.3V or some other supply. Sometimes inputs are externally divided before ADC, sometimes you feed higher voltages directly to ADC, and it depends on ADC. Outputs might not be stepped up with amplifiers, just driven with transistors through level shifter - but whether you count that as an amplifier is another thing. Unless you find schematics or open the ECU and do measurements and reverse-engineering, these questions cannot be answered. | |
| Dec 5, 2023 at 17:18 | comment | added | Puffafish | Some questions which may help you: electronics.stackexchange.com/questions/6403/… and electronics.stackexchange.com/questions/665524/… | |
| Dec 5, 2023 at 17:16 | comment | added | user319168 | Here's a better link for the datasheet... According to this datasheet, there are four VSS pins that can be used for referencing: VSS1 to VSS4, stands for "Voltage Sensor Supply", contrary to normal reference nomenclature, VSS1 to 3 says it outputs 5V and 4 outputs 10V. You'd need a separate PMIC to step down to 3.3V. | |
| Dec 5, 2023 at 17:15 | comment | added | Tim Williams | More or less, yes. Did you want a more specific answer to any of these questions? | |
| Dec 5, 2023 at 17:15 | comment | added | Puffafish | Why do you think cars use 12V? I have driven cars which have a 48V as it's battery, and others with 415V. You're used to a 12V lead acid battery which is used to power the lights etc. That is because that's a convient votlage for those devices. This voltage gets stepped down to something useful for each device. For example in the radio it gets stepped down to 1.8V or even 1V for the components in it, the same goes for the ECU. Like your computer at home, it gets 110V/220V AC in, it gets stepped down to a useful voltage inside the computer. | |
| S Dec 5, 2023 at 17:04 | review | First questions | |||
| Dec 5, 2023 at 19:23 | |||||
| S Dec 5, 2023 at 17:04 | history | asked | Max F | CC BY-SA 4.0 |