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NXP Semiconductors MC33978AEKR2
- Part No.:
- MC33978AEKR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-SSOP (0.295", 7.50mm Width) Exposed Pad
- Datasheet:
-
MC33978AEKR2.pdf
- Description:
- IC INTERFACE SPECIALIZED 32SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,100
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Product details
Overview
MC33978AEKR2 from NXP Semiconductors is a 22-channel switch detection interface IC designed for automotive and industrial control panels. It monitors up to 14 switch-to-ground (SG) and 8 programmable switch (SP) inputs, delivers state changes via SPI, supports selectable wetting currents (2–20 mA), and integrates a 24:1 analog multiplexer with battery voltage (via SG5/÷6) and die temperature sensing - all operating from 4.5 V to 36 V supply.
For engineers reviewing the MC33978AEKR2 datasheet, MC33978AEKR2 pinout, MC33978AEKR2 application, or MC33978AEKR2 equivalent, this device is critical for robust, low-power switch monitoring in harsh environments where precise wetting current control, LPM sleep current ≤30 µA, and integrated analog sensing reduce external component count and improve system reliability.
Technical Context
The MC33978AEKR2 implements dual-mode switch detection logic: Normal mode enables full SPI programming and active wetting current sourcing (pulse or continuous), while Low-power Mode (LPM) uses a 192 kHz internal oscillator to periodically poll inputs with <30 µA VBATP quiescent current. Its 24:1 analog multiplexer routes buffered SG/SP signals to AMUX, with hardwired or SPI-selectable channel routing and dedicated divider-by-6 on SG5 for battery sensing.
Switch input handling includes programmable wetting current per channel (8 levels), ±1.0 V to 36 V input range, glitch filtering (5–18 µs), and configurable wake-up on state change. The SPI interface operates up to 8 MHz with 3.3 V/5.0 V logic compatibility, and fault protection covers VBATP UV/OV, thermal shutdown (155 °C), and ESD (±8 kV contact on VBATP/WAKE_B).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channels | 22 total: 14 SG + 8 SP inputs; supports switch-to-ground or switch-to-battery configurations |
| Wetting Current | Selectable 2, 6, 8, 10, 12, 14, 16, or 20 mA per channel; pulse or continuous operation |
| LPM Supply Current | IBATP = 30 µA max at 6–28 V; enables ultra-low sleep power for always-on automotive systems |
| Supply Range | VBATP: 4.5–36 V (functional), 6.0–28 V (full parametric); VDDQ: 3.0–5.25 V for SPI I/O |
| Analog MUX | 24:1 multiplexer with buffered AMUX output; includes SG5 ÷6 for battery sensing and die temp readout |
| SPI Interface | Up to 8 MHz clock; 3.3 V/5.0 V compatible; supports CS_B, SCLK, MOSI, MISO, INT_B, WAKE_B |
| Operating Temp | -40 °C to +125 °C; qualified per AEC-Q100 for automotive under-hood and dashboard applications |
Pinout & Package
MC33978AEKR2 is packaged in SOICW-EP (32-pin, exposed pad), with thermal pad recommended to be connected to GND and system ground per datasheet layout guidance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Ground reference | Common return for logic, analog, and power domains; connects to exposed pad |
| MOSI (Pin 2) | SPI data input | Receives register write commands and configuration data from MCU |
| SCLK (Pin 3) | SPI clock input | Drives synchronous communication; supports up to 8 MHz operation |
| CS_B (Pin 4) | SPI chip select | Active-low enable; falling edge initiates SPI transaction; internal 40–270 kΩ pull-up |
| SP0–SP7 (Pins 5–12) | Programmable switch inputs | Configurable as switch-to-ground or switch-to-battery; support wetting current sourcing |
| SG0–SG13 (Pins 13–24, 25–26, 27–32) | Switch-to-ground inputs | Dedicated SG pins with sustain/wetting current; SG5 routed to ÷6 battery divider |
| VBATP (Pins 16, 17) | Battery supply input | Primary power rail (4.5–36 V); requires external reverse-battery diode per datasheet |
| WAKE_B (Pin 18) | Wake-up control | Open-drain output to enable external power rails; also accepts falling-edge wake request |
| INT_B (Pin 29) | Interrupt output | Open-drain signal indicating switch state change; used for MCU event-driven polling |
| AMUX (Pin 30) | Analog multiplexer output | Buffered analog output of selected SG/SP channel or derived signals (battery/temp) |
| VDDQ (Pin 31) | Logic supply | 3.3 V/5.0 V supply setting SPI I/O voltage level and internal logic thresholds |
| MISO (Pin 32) | SPI data output | Transmits switch status, fault flags, and analog readings; tri-state capable |
Key Features
| Feature | Design Value |
|---|---|
| Programmable wetting current | Eight discrete levels (2–20 mA) per channel enable optimized contact cleaning without overcurrent stress |
| Integrated analog sensing | AMUX provides calibrated battery voltage (SG5/÷6, ±5% accuracy) and die temperature (8 mV/°C) without external ADC |
| Low-power polling architecture | 192 kHz LPM oscillator enables periodic input sampling at <30 µA IBATP, eliminating MCU wake cycles |
| Robust input protection | ±14 V to +38 V switch input range, ±8 kV contact ESD on VBATP/WAKE_B, and internal UV/OV/thermal fault detection |
| Flexible wake-up control | Configurable interrupt (INT_B) and bidirectional WAKE_B pin allow both autonomous and MCU-initiated exit from LPM |
Applications
| Automotive Door Module | Industrial Control Panel |
|---|---|
Use Scenario: Monitoring door lock/unlock, window up/down, mirror fold/unfold, and interior light switches in vehicle door modules. IC Role / Device Role / Timing Role: Centralized switch interface providing SPI-based status reporting and wetting current to prevent contact oxidation in high-vibration, wide-temperature environments. Use Value: Reduces wiring harness complexity by consolidating 22 discrete switch inputs into one SPI bus; eliminates need for external wetting drivers or analog front-ends. | Use Scenario: Reading pushbuttons, toggle switches, and emergency stop contacts on factory HMIs and machine control cabinets. IC Role / Device Role / Timing Role: High-reliability switch monitor with LPM capability for energy-sensitive remote enclosures and battery-backed systems. Use Value: Enables >10-year battery life in wireless control nodes via 30 µA sleep current; integrated AMUX simplifies battery health monitoring. |
| Heavy-Duty Vehicle Dashboard | Off-Highway Equipment Console |
Use Scenario: Detecting ignition key position, hazard lights, wiper speed, and headlight mode switches in commercial truck dashboards. IC Role / Device Role / Timing Role: Automotive-grade switch detector with extended 4.5–36 V operation tolerating load-dump transients and cold-crank conditions. Use Value: Maintains functional operation down to 4.5 V during cranking; wetting current prevents corrosion in humid, salt-laden cab environments. | Use Scenario: Monitoring engine start/stop, hydraulic valve controls, and safety interlocks in construction, agricultural, and mining equipment. IC Role / Device Role / Timing Role: Ruggedized switch interface supporting -40 °C to +125 °C ambient, with integrated diagnostics for predictive maintenance. Use Value: On-chip temperature monitoring and fault flags (UV/OV/thermal) reduce BOM cost and improve system-level diagnostic coverage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switch detection interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33978EK | Same core functionality and pinout; lacks 'A' grade qualification (MC33978AEKR2 is AEC-Q100 Grade 1, -40°C to +125°C; MC33978EK is not AEC-qualified) | Not suitable for automotive safety-critical or under-hood applications requiring AEC-Q100 compliance | Select MC33978AEKR2 for production automotive designs; MC33978EK only for non-automotive prototyping or cost-sensitive industrial use |
| MC34978AEK | Pin-compatible variant with identical SOICW-EP package and pinout; differs in internal wetting current calibration and LPM timing stability | Optimized for higher-accuracy wetting current matching (±6% vs ±10% for SG) and tighter LPM oscillator tolerance (±10% vs ±15%) | Choose MC34978AEK when precise wetting consistency across channels or stable LPM polling intervals are required |
Compared with MC33978EK and MC34978AEK, the MC33978AEKR2 offers certified automotive reliability (-40°C to +125°C, AEC-Q100 Grade 1), balanced wetting current accuracy, and proven integration in production door modules - making it the default choice for Tier 1 automotive suppliers needing validated performance and supply continuity.
Availability
MC33978AEKR2 is available at Aetrix Electronics and suitable for automotive door modules, industrial HMI panels, heavy-duty vehicle dashboards, and off-highway equipment consoles requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for MC33978AEKR2 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 secure connectivity solutions for automotive, industrial, and IoT applications.
The MC33978AEKR2 belongs to NXP's automotive system basis chip (SBC) and interface portfolio, engineered specifically for robust, low-power switch monitoring in harsh environments - enabling simplified wiring, reduced ECU pin count, and enhanced contact reliability in vehicle body electronics.
FAQ
What is the minimum VBATP voltage required for full parametric operation of the MC33978AEKR2?
The MC33978AEKR2 requires VBATP ≥ 6.0 V for full parametric operation - including guaranteed wetting current accuracy, switch detection thresholds, and LPM current specs. Below 6.0 V (down to 4.5 V), the device remains functional but exhibits degraded parameters such as reduced wetting current headroom and lowered VICTHR threshold; design margins must be verified per application.
How does the MC33978AEKR2 handle switch debouncing and noise immunity?
The MC33978AEKR2 incorporates a programmable input glitch filter with 5–18 µs timer in Normal mode and 1.0–1.4 ms additional debounce time in Low-power Mode. Combined with hysteresis on the 4.0 V switch detection threshold (80–300 mV), this ensures reliable rejection of mechanical bounce and EMI-induced transients without requiring external RC networks.
Can the MC33978AEKR2 measure battery voltage directly, and what is its accuracy?
Yes - the MC33978AEKR2 measures battery voltage via SG5 configured as a ÷6 analog divider. Accuracy is ±5.0% over full temperature range (-40°C to +125°C), with ±3.0% divider coefficient accuracy across 6.0–28 V VBATP. Calibration at 12 V and 25 °C improves precision, and the buffered AMUX output allows direct MCU ADC reading without external components.
What are the wake-up sources supported by the MC33978AEKR2 in Low-power Mode?
In Low-power Mode, the MC33978AEKR2 supports wake-up via: (1) change-of-state on any enabled SG or SP input, (2) falling edge on the WAKE_B pin, and (3) falling edge on CS_B (with tCSB_WAKEUP ≤ 1000 µs). All wake events trigger an interrupt on INT_B and restore Normal mode operation within defined timing limits.
Is the MC33978AEKR2 pin-compatible with other variants in the 33978 family?
Yes - the MC33978AEKR2 (SOICW-EP 32-pin) shares identical pinout and footprint with MC33978EK, MC33978AES, MC34978AEK, and MC34978AES. This enables drop-in replacement across AEC-Q100 qualified and non-qualified variants, provided system-level requirements (e.g., temperature grade, wetting accuracy, oscillator stability) are verified.
MC33978AEKR2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 32-SSOP (0.295", 7.50mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Multiple Switch Detection
- Interface:
- SPI
- Voltage - Supply:
- 3V ~ 5.25V
- Supplier Device Package:
- 32-SOIC-EP
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
MC33978AEKR2 FAQ
1.How can I place an order for MC33978AEKR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33978AEKR2 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 MC33978AEKR2 reliable?
The price and inventory of MC33978AEKR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33978AEKR2 is usually 5 days.
3.What payment methods are accepted for MC33978AEKR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33978AEKR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33978AEKR2?
MC33978AEKR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33978AEKR2 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 MC33978AEKR2?
For technical support, including MC33978AEKR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33978AEKR2 requirements.
6.How does Aetrix verify that MC33978AEKR2 is sourced from the original manufacturer or authorized distributors?
All MC33978AEKR2 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 MC33978AEKR2 meets industry standards.
7.What is the process for return or replacement of MC33978AEKR2?
All MC33978AEKR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC33978AEKR2, 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 MC33978AEKR2 part is unused and in its original packaging.
Return procedure for MC33978AEKR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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