Project Overview and Design Insights

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General
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BOM
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Here’s a concise, system-level explanation of your project “MBR_NMS_ADC_v1.”
What it is and purpose
  • The design implements multi-channel analog signal conditioning for MCU ADC inputs. Channel names (e.g., RR_WSS, RL_WSS, Coolant_Temp) indicate vehicle sensor signals being level-shifted, filtered, buffered, and protected before reaching the MCU ADC rails.
  • Each channel follows a similar front-end topology: input protection and attenuation, low-pass filtering, and op-amp buffering/gain, with clearly labeled ADCx_In and ADCx_Out net portals for integration to the main controller.
Core components and roles

Table

ComponentRole in the system
U1, U2, U3, U4, U5Five dual op-amps forming multiple conditioning stages (buffering, gain/attenuation, and active filtering) per ADC channel. All V+ pins share a common analog supply (Net 11), and V− pins tie to GND.
Generic resistors/capacitors (various designators)Form input attenuators, RC anti-alias filters, op-amp feedback networks, and supply decoupling on the analog rail.
Schottky protection diodes (multiple)Provide fast clamping paths for over/under-voltage events at inputs. A dedicated higher-current Schottky D4 is used where stronger clamping or power-path steering is needed.
Net portals (ADCx_In / ADCx_Out)Define per-channel interfaces: “In” from the sensor harness, “Out” to MCU ADC pins, enabling clean, repeated channel blocks.
12V power net portalsIndicate an automotive 12V domain present in the system; diodes and passives reference it for clamping/steering and rail awareness.
How the blocks interact
  • Sensor inputs feed protection/conditioning networks. Schottky diodes clamp excursions (fast transients, reverse polarity, inductive kick) away from sensitive analog nodes.
  • RCs provide anti-alias filtering and ensure the ADC’s sample-and-hold capacitor can settle. Resistor dividers/feedback networks adjust signal level and impedance.
  • Op-amps buffer and shape signals to present a low-impedance, bandwidth-limited, ADC-friendly waveform on the ADCx_Out nets.
  • A shared analog supply (Net 11) powers all op-amps; distributed decoupling capacitors connect from Net 11 to GND near the ICs.
Design choices, trade-offs, optimizations
  • Using replicated LM358-based stages simplifies scaling to many channels and keeps BOM uniform. Trade-off: LM358 is not rail-to-rail; verify input/output swing vs supply rails and expected signal ranges.
  • Schottky clamping is fast and low-loss; trade-off: leakage and forward-drop vary with temperature, and clamping into MCU rails must respect MCU injection limits.
  • Passive RC filters are simple and robust; trade-off: too high output impedance or too low cutoff can slow settling during ADC acquisition. Knowledge-base guidance: do not assume fixed limits; compute permissible source impedance from the MCU’s Tacq and internal sampling capacitor.
  • Centralized analog supply and distributed decoupling are good for noise; optimization opportunity: place capacitors as close as possible to each op-amp’s V+ pin and tailor values (e.g., 100 nF + 1–10 µF per rail group) per layout constraints.
Key technologies and dependencies
  • Multi-op-amp analog signal conditioning per channel (buffer, filter, attenuate).
  • Schottky-based input protection for transient events and ESD-like conditions.
  • Automotive-adjacent power awareness (12V presence), implying susceptibility to load dumps and inductive transients; robust protection strategy is important (series R for clamp current limiting, TVS diodes, optional PTCs).
  • MCU ADC timing dependencies: source impedance and RC time constants must be matched to the ADC acquisition time so the input settles within 0.5 LSB over the sample window.
Challenges and performance considerations
  • ADC drive and settling: ensure the effective source impedance seen by the ADC plus any RC filter meets the MCU’s Tacq requirement. If not, reduce R or increase drive via the op-amp.
  • Clamp current into MCU pins: when using rail clamps, compute clamp current using I = (V_in - Vdd - Vf)/R and verify it is below the MCU’s maximum injection rating.
  • Op-amp headroom and linearity: check input common-mode and output swing vs expected min/max signals and supply voltage. Non-rail-to-rail devices can saturate near ground or supply.
  • Noise and aliasing: pick filter cutoff relative to the ADC sampling rate and signal bandwidth. Include the ADC’s S/H kickback in stability considerations.
  • Automotive transients: if the inputs can see the vehicle harness, add appropriate surge/ESD/load-dump protection (TVS diode selection, series impedance, and robust return paths).
Real-world applications
  • Conditioning of vehicle sensors (e.g., thermistors for coolant temperature, analog wheel/speed sensors with appropriate conversion) into an MCU for logging, control, or telemetry.
  • Any multi-channel analog acquisition where inputs must be protected, scaled, and filtered prior to digitization.
Areas for improvement and future enhancements
  • Specify values: replace generics with calculated resistor/capacitor values per each sensor’s range, desired bandwidth, MCU ADC Tacq, and reference voltage.
  • Validate op-amp choice: confirm LM358 meets bandwidth, slew-rate, input/output swing, and offset/noise targets for your signals; if not, consider rail-to-rail, low-noise alternatives.
  • Harden protection: for automotive exposure, consider a three-element scheme per input (series resistor, TVS diode to GND/rails, and resettable PTC) and validate to relevant surge/ESD standards.
  • Reference strategy: ensure ADC reference filtering and stability; align channel scaling so typical signals use most of the ADC’s dynamic range.
  • Grounding/layout: tightly couple decoupling to each op-amp, separate high-current returns from sensitive analog grounds, and minimize loop areas on input/protection paths.
  • Scalability: encapsulate each channel as a module for easy replication; standardize connectors/net portals and test pads for production test and calibration.
If you want, I can review specific channels or compute the exact RC and gain networks against your MCU’s ADC timing and reference. Just share the MCU model/reference and the intended input ranges per sensor.
Channel deep dive
Choose op-amp
Size RC network
Input protection upgrade
ADC drive check
62 days

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R13
Resistance
82 Ω
D1
End of Life
RR_WSS_ADC
U1
Not Recommended for New Designs
R1
Resistance
10k Ω
R3
Resistance
3.8k Ω
C6
Capacitance
0.1u F
RR_WSS
R9
Resistance
82 Ω
ADC1_In
R5
Resistance
82 Ω
ADC1_In
12V
ADC2_Out
RL_WSS
R7
Resistance
10k Ω
R10
Resistance
5k Ω
R11
Resistance
9.7k Ω
U2
Not Recommended for New Designs
U3
Not Recommended for New Designs
D3
End of Life
C2
Capacitance
.1u F
R12
Resistance
5k Ω
C3
Capacitance
1u F
RL_WSS_ADC
R2
Resistance
3.8k Ω
C1
Capacitance
0.1u F
D2
End of Life
R4
Resistance
10k Ω
R6
Resistance
9.7k Ω
D5
End of Life
ADC1_Out
12V
C5
Capacitance
1u F
C4
Capacitance
1u F
  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
    20.5M
  • Net Portal
    Net Portal
    Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
    jharwinbarrozo
    43.0M
  • Power Net Portal
    Power Net Portal
    Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
    jharwinbarrozo
    11.4M
  • Generic Resistor
    Generic Resistor
    A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Capacitor
    Generic Capacitor
    A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Inductor
    Generic Inductor
    A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
    jharwinbarrozo
    15.1k
  • Terminal
    Terminal
    An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
    natarius
  • RMCF0805JT47K0
    RMCF0805JT47K0
    47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
    jharwinbarrozo
    1.2M
  • 875105359001
    875105359001
    10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
    jharwinbarrozo
    1.2M
  • CTL1206FYW1T
    CTL1206FYW1T
    Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
    jharwinbarrozo
    1.1M

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MBR_NMS_ADC_v1

MBR_NMS_ADC_v1
Description

Created
Last updated by psuser2024
3 Contributor(s)
kolmanpg
garrett-pan
psuser2024

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