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NXP Semiconductors MC34978AEK
- Part No.:
- MC34978AEK
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-SSOP (0.295", 7.50mm Width) Exposed Pad
- Datasheet:
-
MC34978AEK.pdf
- Description:
- IC INTERFACE SPECIALIZED 32SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,112
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Product details
Overview
MC34978AEK from NXP Semiconductors is a 22-channel switch detection interface IC with programmable wetting current, SPI communication, and integrated 24:1 analog multiplexer. It supports 14 switch-to-ground (SG) and 8 programmable switch (SP) inputs, operates from 4.5 V to 36 V, delivers 30 µA VBATP quiescent current in low-power mode, and enables battery voltage sensing via SG5 divider and die temperature monitoring - deployed in automotive body control modules for door/window/seat switch monitoring.
For engineers reviewing the MC34978AEK datasheet, MC34978AEK pinout, MC34978AEK application, or MC34978AEK equivalent, this page provides verified technical context, SOICW-EP package details, real-world use scenarios, validated alternatives, and supply-chain support for production-grade automotive electronics design.
Technical Context
The MC34978AEK implements dual-mode switch monitoring: Normal mode supplies configurable wetting current (2–20 mA, 8 levels) for contact cleaning and state detection, while Low-power Mode (LPM) uses a 192 kHz internal oscillator and periodic polling to achieve 30 µA VBATP supply current. Its 24:1 analog multiplexer routes SG/SP inputs, battery voltage (via SG5 ÷6), and on-die temperature to AMUX for MCU ADC sampling.
Switch inputs tolerate −1.0 V to 36 V, with dedicated 4.0 V comparator thresholds (±300 mV hysteresis) and glitch filtering (5–18 µs). Wake-up is supported via WAKE_B (open-drain) and INT_B (active-low interrupt), both configurable for edge-triggered LPM exit. SPI interface operates up to 8 MHz with 3.3 V/5.0 V logic compatibility via VDDQ.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channels | 22 total: 14 SG + 8 SP inputs - enables centralized monitoring of door latches, seat position sensors, and ignition switches without discrete pull resistors. |
| Wetting Current | Programmable 2–20 mA (8 levels) - ensures reliable contact cleaning across varying switch resistance and environmental contamination. |
| LPM Supply Current | 30 µA (VBATP), 10 µA (VDDQ) - meets automotive sleep-current budgets for always-on body control units. |
| Input Voltage Range | −1.0 V to 36 V - withstands load dump, reverse battery, and cold-crank conditions per ISO 7637-2. |
| AMUX Functionality | 24:1 analog mux with buffered output, SG5 ÷6 battery sensing, and integrated temperature sensor - eliminates need for external ADC channels or voltage dividers. |
| SPI Interface | Up to 8 MHz, 3.3 V/5.0 V compatible via VDDQ - enables direct connection to common automotive MCUs without level-shifting. |
| Operating Temp | −40 °C to +105 °C - qualified for under-hood and cabin-mounted applications per AEC-Q100 Grade 2. |
Pinout & Package
MC34978AEK is housed in a 32-pin SOICW-EP (wide-body, exposed pad) package, optimized for thermal dissipation and automotive board-level reliability. The exposed pad must be soldered to system ground per NXP layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Ground reference | Primary logic/analog ground; exposed pad must connect to same net for thermal and EMI performance. |
| VBATP (Pins 16,17) | Battery supply input | High-side power rail requiring external reverse-battery protection diode; supports 4.5–36 V operation. |
| VDDQ (Pin 31) | Digital supply | 3.3 V/5.0 V logic supply setting SPI I/O voltage levels and internal buffer thresholds. |
| CS_B, SCLK, MOSI, MISO (Pins 4,3,2,32) | SPI interface | Standard 4-wire SPI with tri-state MISO; CS_B active-low enables register access and status reads. |
| INT_B (Pin 29) | Interrupt output | Open-drain signal indicating switch state change; also accepts falling-edge wake-up in LPM. |
| WAKE_B (Pin 17) | Wake-up control | Open-drain output to enable external power rails; doubles as input for external wake events. |
| AMUX (Pin 30) | Analog multiplexer output | Buffered analog output carrying selected SG/SP channel, battery voltage (÷6), or temperature sensor data. |
| SG0–SG13 (Pins 9–15,18–24) | Switch-to-ground inputs | 14 dedicated low-side switch inputs with programmable wetting/sustain current and ±1 V fault tolerance. |
| SP0–SP7 (Pins 5–8,25–28) | Programmable switch inputs | 8 configurable inputs supporting switch-to-ground or switch-to-battery modes with independent current settings. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable wetting current | 8 selectable levels (2–20 mA) with pulse/continuous operation - prevents contact oxidation in infrequently actuated switches like trunk release or hood latch. |
| Integrated battery & temperature sensing | SG5 ÷6 ratio accuracy ±3% over 6–28 V; die temp coefficient 8.0 mV/°C - enables system-level health monitoring without external components. |
| Low-power mode architecture | 192 kHz LPM oscillator + configurable polling timer - achieves 30 µA VBATP draw while maintaining <1.4 ms debounce and wake latency. |
| Robust input protection | −1.0 V to 36 V input range, ±15 kV CDM ESD on SG/SP pins, integrated 4.0 V comparator with 300 mV hysteresis - survives harsh automotive harness environments. |
| Hardwire AMUX selection | Two- or three-pin hardware configuration for fixed analog channel routing - eliminates SPI overhead for critical battery/temperature reads during boot or fault recovery. |
Applications
| Door Module Switch Monitoring | Seat Position Sensing System |
|---|---|
Use Scenario: Real-time detection of door open/close, window up/down, and mirror fold/unfold switches in vehicle door modules. IC Role / Device Role / Timing Role: Centralized switch interface IC performing wetting current injection, state polling, and SPI reporting to door ECU MCU. Use Value: Reduces BOM count by replacing 22 discrete pull-up resistors and external protection networks; LPM current <30 µA extends battery life during vehicle sleep. |
Use Scenario: Monitoring multi-position seat adjustment switches (forward/back, recline, height) and memory preset buttons. IC Role / Device Role / Timing Role: High-voltage-tolerant switch detector with programmable wetting current ensuring reliable contact closure detection despite lubricant buildup. Use Value: Eliminates false triggers from contact bounce or corrosion; AMUX enables simultaneous seat position feedback and battery voltage health check via single MCU ADC channel. |
| Ignition & Start Button Interface | Roof Console Control Panel |
Use Scenario: Reading push-button ignition, start/stop, and hazard light switches in center console or steering column modules. IC Role / Device Role / Timing Role: SPI-connected switch monitor with fast interrupt response (<18.5 µs) and wake-on-change capability for immediate MCU activation. Use Value: Enables instant system wake from deep sleep; 4.0 V detection threshold with hysteresis prevents misreads during cranking voltage sag (down to 4.5 V). |
Use Scenario: Managing sunroof open/close, interior lamp dimming, and air recirculation controls in overhead console assemblies. IC Role / Device Role / Timing Role: Analog multiplexer hub routing switch states and ambient temperature readings to main body controller via shared SPI bus. Use Value: Consolidates 8+ SP/SG inputs and thermal monitoring into one IC; AMUX hardwire mode allows deterministic timing for safety-critical sunroof position feedback. |
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 | Same SOICW-EP package, identical pinout and register map; rated for −40 °C to +125 °C (vs. MC34978AEK's +105 °C max). | Preferred for under-hood applications requiring extended junction temperature operation. | Select MC33978AEK when ambient exceeds 105 °C; otherwise MC34978AEK offers cost-optimized qualification for cabin modules. |
| MC34978AES | QFN-32 (WF-Type) package, same electrical specs; lacks exposed pad thermal path and requires different PCB layout. | Suitable for space-constrained designs where SOICW footprint is prohibitive. | Choose MC34978AES only if board area is critical and thermal management via PCB copper is feasible. |
Compared with MC33978AEK, the MC34978AEK trades 20 °C junction margin for optimized cost and qualification scope in cabin applications; versus MC34978AES, it delivers superior thermal performance and drop-in compatibility with existing SOICW layouts - making it the default choice for new body control module designs targeting 105 °C ambient.
Availability
MC34978AEK is available at Aetrix Electronics and suitable for automotive body control modules, seat/door ECU designs, and roof console systems requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.
Supply support for MC34978AEK 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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in automotive-grade mixed-signal ICs.
The MC34978AEK belongs to NXP's automotive switch interface product line, engineered specifically for robust, low-power monitoring of mechanical switches in vehicle body electronics - balancing high-voltage resilience, parametric accuracy, and system-level integration.
FAQ
What is the maximum operating temperature for the MC34978AEK?
The MC34978AEK is qualified for operation from −40 °C to +105 °C ambient temperature. Its thermal shutdown activates at 155 °C junction temperature with 3 °C hysteresis. This rating makes the MC34978AEK suitable for cabin-mounted applications such as door modules and roof consoles, but not under-hood locations exceeding 105 °C ambient - for those, the MC33978AEK (−40 °C to +125 °C) is recommended. The SOICW-EP package's exposed pad enhances thermal dissipation to maintain safe junction temperatures under full load.
Does the MC34978AEK support both switch-to-ground and switch-to-battery configurations?
Yes, the MC34978AEK supports both configurations: 14 dedicated switch-to-ground (SG) inputs and 8 programmable switch (SP) inputs that can be configured as either switch-to-ground or switch-to-battery (SB) via SPI register settings. Each SP channel has independent wetting current control, and SB inputs use a higher sustain current (2.2 mA typical) compared to SG (2.0 mA). The IC tolerates −1.0 V to 36 V on all switch inputs, enabling direct connection to battery-rail switches without external level-shifting or clamping.
How does the AMUX function work on the MC34978AEK?
The MC34978AEK's 24:1 analog multiplexer routes signals from SG/SP inputs, battery voltage (via SG5 ÷6), and on-die temperature to the AMUX pin for MCU ADC sampling. Selection is controlled via SPI or hardwired using two or three pins for fixed channel mapping - eliminating SPI overhead during critical reads. The AMUX output is buffered, with offset ≤±10 mV (EK suffix), and supports sink/source currents up to 1 mA. This integrated functionality replaces external multiplexers, voltage dividers, and temperature sensors in body control applications.
What is the wetting current range and resolution on the MC34978AEK?
The MC34978AEK provides eight programmable wetting current levels: 2, 6, 8, 10, 12, 14, 16, and 20 mA - selectable per channel via SPI. Wetting can operate in pulse mode (20 ms duration) or continuous mode. Current matching between channels is ≤6% for wetting and ≤10% for sustain, ensuring consistent contact cleaning across all 22 inputs. At low battery (4.5–6.0 V), wetting current remains accurate within ±20% for SB and ±10% for SG, preserving reliability during cold-crank conditions.
Can the MC34978AEK wake the MCU from low-power mode?
Yes, the MC34978AEK supports two independent wake-up mechanisms from Low-power Mode (LPM): (1) an active-low interrupt on INT_B triggered by switch state change, and (2) edge-triggered wake-up via WAKE_B input. Both signals are configurable for rising/falling edge sensitivity. LPM wake latency is guaranteed ≤1000 µs (typical 755 µs) when triggered by CS_B edge. This enables rapid system response while maintaining 30 µA VBATP quiescent current - meeting stringent automotive sleep-mode requirements for body electronics.
MC34978AEK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 32-SSOP (0.295", 7.50mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Multiple Switch Detection
- Interface:
- -
- Voltage - Supply:
- 4.5V ~ 36V
- Supplier Device Package:
- 32-SOIC-EP
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
MC34978AEK FAQ
1.How can I place an order for MC34978AEK through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34978AEK 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 MC34978AEK reliable?
The price and inventory of MC34978AEK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978AEK is usually 5 days.
3.What payment methods are accepted for MC34978AEK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978AEK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34978AEK?
MC34978AEK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34978AEK 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 MC34978AEK?
For technical support, including MC34978AEK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978AEK requirements.
6.How does Aetrix verify that MC34978AEK is sourced from the original manufacturer or authorized distributors?
All MC34978AEK 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 MC34978AEK meets industry standards.
7.What is the process for return or replacement of MC34978AEK?
All MC34978AEK units undergo pre-shipment inspection (PSI). If there is an issue with MC34978AEK, 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 MC34978AEK part is unused and in its original packaging.
Return procedure for MC34978AEK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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