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NXP Semiconductors MC33978AAER2
- Part No.:
- MC33978AAER2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
MC33978AAER2.pdf
- Description:
- MSDI2
- Quantity:
- Payment:
- Shipping:
Inventory:1,708
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Product details
Overview
MC33978AAER2 from NXP Semiconductors is a 22-channel automotive-grade switch detection interface IC with programmable wetting current (2–20 mA), SPI communication, and integrated 24:1 analog multiplexer. It monitors up to 14 switch-to-ground (SG) and 8 programmable switch (SP) inputs, supports Normal/Low-power/Polling modes, and delivers battery voltage sensing (via SG5/÷6) and die temperature monitoring through the AMUX pin. Used in vehicle door modules, seat controls, and steering column switches.
For engineers reviewing the MC33978AAER2 datasheet, MC33978AAER2 pinout, MC33978AAER2 application, or MC33978AAER2 equivalent, this page provides verified technical context, validated pin functions, confirmed operating ranges (4.5–36 V), real-world switch detection thresholds (4.0 V nominal), and documented alternative options for automotive body electronics design.
Technical Context
The MC33978AAER2 implements dual-mode wetting current control-pulse or continuous-with eight selectable levels (2, 6–20 mA) per channel, enabling reliable contact cleaning across diverse switch types and environmental conditions. Its internal 192 kHz LPM oscillator enables ultra-low-quiescent-current operation (30 µA on VBATP, 10 µA on VDDQ) while maintaining wake-up capability via INT_B or WAKE_B.
It integrates a buffered 24:1 analog multiplexer with hardwired or SPI-selectable inputs, delivering calibrated battery voltage (SG5 ÷6, ±5% accuracy) and die temperature (8 mV/°C coefficient) on the AMUX output pin. Switch state detection uses a 4.0 V comparator threshold with 80–300 mV hysteresis and configurable glitch filtering (5–18 µs).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Channels | 22 total: 14 SG (switch-to-ground) + 8 SP (programmable SB/SG) |
| Wetting Current | Selectable 2, 6, 8, 10, 12, 14, 16, or 20 mA per channel; pulse or continuous mode |
| Supply Range | VBATP: 4.5–36 V (full parametric spec at 6.0–28 V); VDDQ: 3.0–5.25 V |
| Low-Power Mode Current | IBATP = 30 µA, IDDQ = 10 µA - enables <100 µA system sleep current in automotive body modules |
| AMUX Functionality | 24:1 analog mux with buffered output; includes SG5 ÷6 battery sensing and on-die temperature sensor (8 mV/°C) |
| SPI Interface | 3.3 V / 5.0 V compatible; max 8 MHz clock; supports interrupt-driven polling and register-based configuration |
| Operating Temp | -40 °C to +125 °C - qualified for under-hood and interior automotive applications |
Pinout & Package
LQFP-EP 48-pin package with exposed thermal pad (EP), rated for -40 °C to +125 °C ambient operation. Pin 1 is GND; EP must be connected to system ground for thermal and EMI performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1, 19, 42, 43) | Ground reference | Common return for logic, analog, and power domains; multiple pins reduce impedance and improve noise immunity |
| VBATP (Pins 16, 17) | Battery supply input | Primary power rail (4.5–36 V); requires external reverse-battery protection diode per datasheet Figure 24 |
| VDDQ (Pin 41) | Logic supply | 3.3 V / 5.0 V digital I/O supply; sets SPI level and buffer thresholds |
| CS_B, SCLK, MOSI, MISO (Pins 47–42) | SPI interface | Standard 4-wire SPI with tri-state MISO; supports daisy-chaining and multi-drop configurations |
| INT_B (Pin 39) | Open-drain interrupt | Active-low signal indicating switch state change; also accepts falling-edge wake-up in LPM |
| WAKE_B (Pin 20) | Open-drain wake-up output | Drives external power-enable circuits; configurable as input for external wake events |
| AMUX (Pin 40) | Analog multiplexer output | Buffered analog output for MCU ADC reading; carries battery voltage (÷6), temperature, or selected SG/SP signals |
| SG0–SG13 (Pins 6–12, 25–31) | Switch-to-ground inputs | 14 dedicated low-side switch inputs with programmable wetting current and 4.0 V detection threshold |
| SP0–SP7 (Pins 2–5, 32–35) | Programmable switch inputs | 8 configurable inputs supporting switch-to-battery (SB) or switch-to-ground (SG) topologies |
Key Features
| Feature | Design Value |
|---|---|
| Programmable wetting current | Eight discrete levels (2–20 mA) per channel enable optimized contact cleaning without excessive power draw or thermal stress |
| Integrated battery & temperature sensing | Eliminates need for external ADC channels: SG5 ÷6 provides ±5% battery voltage accuracy; die temp sensed via AMUX at 8 mV/°C |
| Multi-mode operation | Normal (full function), Low-power (30 µA VBATP), and Polling (configurable interval) modes support flexible power management strategies |
| Robust switch input protection | Withstands -1.0 V to 36 V on SG/SP pins; ±15 kV CDM ESD rating on protected pins; designed for direct harness connection |
| Glitch-filtered detection | Configurable 5–18 µs input filter prevents false triggers from mechanical bounce or EMI in automotive environments |
Applications
| Door Module Switch Monitoring | Steering Column Control Panel |
|---|---|
|
Use Scenario: Detecting open/closed status of power window, lock, mirror, and puddle lamp switches mounted in vehicle doors. IC Role / Device Role / Timing Role: Primary switch interface IC; replaces discrete comparators and GPIO expanders; reports state changes via SPI interrupt within 18.5 µs. Use Value: Reduces BOM count by consolidating 22 switch inputs into one IC with built-in wetting current, eliminating external pull resistors and debounce circuitry. |
Use Scenario: Reading multifunction buttons (cruise control, audio, phone, lane assist) on steering wheel assemblies. IC Role / Device Role / Timing Role: High-reliability switch scanner with LPM wake-up; detects press/release events and forwards status to main MCU over SPI. Use Value: Enables <100 µA sleep current in steering column ECU; wetting current ensures consistent contact performance despite grease, dust, and humidity exposure. |
| Seat Position & Memory Control | Roof Console & Sunroof Switches |
|
Use Scenario: Monitoring seat adjustment switches (forward/back, recline, height, lumbar) and memory preset buttons. IC Role / Device Role / Timing Role: Analog-capable switch detector; reads potentiometer wiper position (via AMUX) and discrete switch states simultaneously. Use Value: Combines digital switch scanning and analog sensing in one device, reducing PCB area and interconnect complexity in space-constrained seat modules. |
Use Scenario: Managing sunroof open/close, tilt, vent, and interior light controls located in overhead console. IC Role / Device Role / Timing Role: Fault-tolerant interface with VBATP UV/OV detection and thermal shutdown (155 °C); reports faults via SPI registers. Use Value: Built-in diagnostics (VBATP UV/OV, overtemp, SPI error) simplify ASIL-B compliance and reduce software validation effort for roof systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switch detection interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33978AEK | SOICW-EP 32-pin package; same electrical specs and feature set; no LQFP pin compatibility | Preferred for cost-sensitive, lower-channel-count designs where board space allows SOIC footprint | Select MC33978AEK when thermal requirements permit higher RΘJA (79 °C/W) and layout favors through-hole or wider-pitch surface mount. |
| MC34978AES | QFN 32-pin; identical functionality but rated for -40 °C to +105 °C (vs. +125 °C for MC33978AAER2) | Suitable for non-under-hood applications like center consoles or door panels with lower ambient temp exposure | Choose MC34978AES only if full -40 °C to +125 °C operation is not required and QFN thermal performance (RΘJC = 2.0 °C/W) is advantageous. |
Compared with MC33978AEK and MC34978AES, the MC33978AAER2 offers the widest temperature range (-40 °C to +125 °C) and LQFP-EP package for optimal thermal dissipation in high-density automotive modules, making it the preferred choice for under-hood or high-ambient applications requiring long-term reliability.
Availability
MC33978AAER2 is available at Aetrix Electronics and suitable for automotive body electronics, industrial HMI panels, and commercial vehicle control systems requiring stable component supply, AEC-Q100-compliant performance, and long-lifecycle availability.
Supply support for MC33978AAER2 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
NXP Semiconductors is a global semiconductor leader focused on automotive, industrial, IoT, and communications applications, with deep expertise in automotive electronics and functional safety.
The MC33978AAER2 belongs to NXP's SBC (System Basis Chip) family, designed specifically for robust, low-power switch monitoring and system supervision in automotive body control modules and junction boxes.
FAQ
What is the maximum switch input voltage range supported by the MC33978AAER2?
The MC33978AAER2 supports a switch input voltage range of -1.0 V to 36 V on all SG and SP pins. This wide range accommodates negative transients (e.g., load dump recovery) and high-voltage battery systems, and is validated per AEC-Q100 stress testing including ±15 kV CDM ESD on protected pins. The MC33978AAER2 maintains reliable detection across this range using its programmable wetting current and 4.0 V comparator threshold.
How does the MC33978AAER2 handle low-battery conditions below 6.0 V?
Below 6.0 V, the MC33978AAER2 remains functional down to 4.5 V but operates with degraded parametric values: switch detection threshold drops to 0.55 × VBATP, wetting current accuracy decreases, and some specifications (e.g., IBATP) are guaranteed only functionally-not parametrically. The MC33978AAER2 includes VBATP undervoltage detection (4.3 V rising threshold, 250 mV hysteresis) to alert the MCU before critical failure.
Can the MC33978AAER2 measure battery voltage directly?
Yes-the MC33978AAER2 measures battery voltage via SG5 configured as a ÷6 divider, delivering an accurate analog representation on the AMUX pin. The divider achieves ±5% accuracy over temperature and ±3% coefficient stability across 6–28 V VBATP. Calibration at 12 V/25 °C further improves precision. This eliminates the need for external resistive dividers or dedicated battery monitor ICs in the MC33978AAER2 design.
What is the purpose of the WAKE_B pin on the MC33978AAER2?
The WAKE_B pin on the MC33978AAER2 is an open-drain output used to control external power supplies (e.g., enabling a local 3.3 V regulator), and can also serve as an input to accept wake-up requests from other system components. In Low-power Mode, the MC33978AAER2 asserts WAKE_B low to signal readiness; externally pulled up, it drives downstream circuitry. As an input, a falling edge on WAKE_B wakes the MC33978AAER2 from LPM, synchronizing system-level sleep/wake transitions.
Does the MC33978AAER2 support both switch-to-ground and switch-to-battery topologies?
Yes-the MC33978AAER2 supports both topologies: 14 dedicated SG (switch-to-ground) inputs and 8 programmable SP (switch-to-battery or switch-to-ground) inputs. Each SP channel can be configured in software for SB or SG operation, allowing flexible integration with existing harness architectures. Wetting current, detection thresholds, and debounce settings are independently configurable per channel, ensuring reliable operation regardless of topology.
MC33978AAER2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 48-LQFP Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Multiple Switch Detection
- Interface:
- SPI
- Voltage - Supply:
- 3V ~ 5.25V, 4.5V ~ 36V
- Supplier Device Package:
- 48-HLQFP (7x7)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
MC33978AAER2 FAQ
1.How can I place an order for MC33978AAER2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33978AAER2 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MC33978AAER2 reliable?
The price and inventory of MC33978AAER2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33978AAER2 is usually 5 days.
3.What payment methods are accepted for MC33978AAER2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33978AAER2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33978AAER2?
MC33978AAER2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33978AAER2 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MC33978AAER2?
For technical support, including MC33978AAER2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33978AAER2 requirements.
6.How does Aetrix verify that MC33978AAER2 is sourced from the original manufacturer or authorized distributors?
All MC33978AAER2 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MC33978AAER2 meets industry standards.
7.What is the process for return or replacement of MC33978AAER2?
All MC33978AAER2 units undergo pre-shipment inspection (PSI). If there is an issue with MC33978AAER2, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MC33978AAER2 part is unused and in its original packaging.
Return procedure for MC33978AAER2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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