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NXP Semiconductors MC33978AESR2
- Part No.:
- MC33978AESR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
MC33978AESR2.pdf
- Description:
- IC INTERFACE SPECIALIZED 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,921
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Product details
Overview
MC33978AESR2 from NXP Semiconductors is a 22-channel automotive-grade switch detection interface IC with programmable wetting current, SPI communication, and integrated 24:1 analog multiplexer. It monitors up to 14 switch-to-ground (SG) and 8 programmable switch (SP) inputs across -1.0 V to 36 V, supports Normal/Low-power/Polling modes, and delivers battery voltage sensing (via SG5/÷6) and die temperature monitoring through the AMUX pin. It is used in vehicle door modules, seat control units, and steering column switch interfaces.
For engineers reviewing the MC33978AESR2 datasheet, MC33978AESR2 pinout, MC33978AESR2 application, or MC33978AESR2 equivalent, key selection criteria include its 30 µA VBATP quiescent current in Low-power mode, ±10% wetting current tolerance across 2–20 mA levels, 4.0 V switch detection threshold with hysteresis, SPI-compatible 3.3 V/5.0 V logic interface, and integrated fault detection (UV/OV/thermal).
Technical Context
The MC33978AESR2 implements dual-current sourcing architecture: sustain current (2.0 mA typical) for steady-state switch biasing and programmable wetting current (6–20 mA in 7 discrete levels) for contact cleaning during state transitions. Its internal 192 kHz LPM oscillator enables precise polling timing, while the 4.0 MHz main oscillator drives SPI and digital logic in Normal mode.
Switch input conditioning includes per-pin glitch filtering (5–18 µs), configurable wake-up on change-of-state, and separate detection thresholds for Normal mode (4.0 V ±0.3 V), Low-power mode (100–300 mV for SG), and low-battery operation (0.55 × VBATP). The AMUX path integrates a buffered op-amp output, fixed ÷6 divider on SG5, and temperature-sensing diode, all selectable via SPI or hardwired pins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Channels | 22 total: 14 SG-only + 8 programmable SP (SG/SB configurable) |
| Wetting Current Range | 2, 6, 8, 10, 12, 14, 16, or 20 mA - selectable per channel for contact cleaning |
| VBATP Quiescent Current (LPM) | 30 µA - enables <100 µA system sleep current in automotive body controllers |
| Input Voltage Range | -1.0 V to 36 V - withstands load dump, reverse battery, and cold-crank conditions |
| SPI Interface | 3.3 V / 5.0 V compatible, up to 8 MHz - direct connection to MCU without level shifters |
| AMUX Functions | 24:1 analog mux with buffered output, SG5 ÷6 battery sensing, and die temperature readout |
| Operating Temp Range | -40 °C to +125 °C - qualified for under-hood and interior automotive applications |
Pinout & Package
MC33978AESR2 is housed in a 32-pin QFN (WF-Type) package with exposed thermal pad. Pin count and layout match SOICW-EP variant; pin functions are electrically identical across QFN and SOICW packages per datasheet Table 2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SG0–SG13 | Switch-to-Ground Input | Dedicated low-side switch inputs with programmable wetting/sustain current |
| SP0–SP7 | Programmable Switch Input | Configurable as switch-to-ground or switch-to-battery; supports SB wetting current |
| VBATP | Battery Supply Input | Primary power rail (4.5–36 V); requires external reverse-battery protection diode |
| VDDQ | Logic Supply Input | 3.3 V / 5.0 V supply setting SPI I/O voltage level and internal logic thresholds |
| CS_B, SCLK, MOSI, MISO | SPI Interface | Standard 4-wire SPI bus; MISO is tri-state capable for multi-device buses |
| INT_B | Open-Drain Interrupt Output | Active-low signal indicating switch state change; also accepts falling-edge wake-up in LPM |
| WAKE_B | Open-Drain Wake-up Output/Input | Drives external power enable; accepts external wake event when pulled low |
| AMUX | Analog Multiplexer Output | Buffered analog output carrying selected SG/SP voltage, battery sense (÷6), or temperature |
| GND / EP | Ground / Exposed Pad | System ground reference; exposed pad must be soldered to PCB ground plane for thermal/EMI performance |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Wetting Current | Eight discrete levels (2–20 mA) with ±10% tolerance - ensures reliable contact cleaning across voltage and temperature |
| Low-Power Mode Operation | 30 µA VBATP supply current with 192 kHz internal oscillator - extends battery life in always-on vehicle modules |
| Integrated Battery Sensing | Fixed ÷6 resistor network on SG5 input - enables accurate 12 V/24 V battery monitoring without external components |
| Thermal Monitoring | On-die temperature sensor routed to AMUX pin - provides real-time junction temperature feedback for derating |
| Robust Input Protection | ±15 kV contact ESD on SG/SP pins (with 100 nF cap + series R) - meets automotive system-level EMC requirements |
| Configurable Wake-up Sources | Per-channel wake-on-change, INT_B edge, CS_B edge, or WAKE_B input - enables flexible low-power system architecture |
Applications
| Door Module Switch Interface | Steering Column Control Unit |
|---|---|
|
Use Scenario: Monitoring 18+ mechanical switches (lock/unlock, window up/down, mirror adjust) in vehicle door module with minimal PCB space and strict sleep-current budget. IC Role / Device Role / Timing Role: Central switch detection hub; replaces discrete comparators and GPIO expanders; handles wetting pulse timing (20 ms ±3 ms) and debounce (1.2 ms typical) autonomously. Use Value: Reduces MCU GPIO count by 22 pins, eliminates external wetting current sources, and achieves <100 µA system sleep current via 30 µA LPM mode. |
Use Scenario: Reading multifunction steering wheel buttons (cruise, audio, phone) in harsh EMI environment with high-voltage transients from adjacent motor drivers. IC Role / Device Role / Timing Role: High-immunity switch interface with -1.0 V to 36 V input range and integrated 100 ns glitch filter; reports state changes via SPI interrupt within 18.5 µs. Use Value: Withstands load dump (38 V max) and ISO 7637-2 pulses without latch-up; eliminates need for external TVS and RC filters on each switch line. |
| Seat Position Memory System | Roof Console Switch Panel |
|
Use Scenario: Detecting position-memory toggle switches and seat heater controls in premium seating systems requiring battery-backed nonvolatile storage of user preferences. IC Role / Device Role / Timing Role: Provides switch status + battery voltage (via SG5/÷6) and die temperature to MCU for safe heater duty-cycle management and low-battery memory retention decisions. Use Value: Integrates three critical sensor functions (switch, battery, temp) into one IC - reduces BOM count, improves calibration consistency, and avoids separate ADC routing. |
Use Scenario: Managing overhead console switches (sunroof, map lights, garage door opener) where space-constrained layout demands minimal passive components and high reliability over 15-year vehicle life. IC Role / Device Role / Timing Role: Fault-tolerant interface with UV/OV/thermal protection flags reported via SPI registers; supports Polling mode for deterministic wake timing in safety-critical sequences. Use Value: Built-in diagnostics (HASH error detect, OV/UV flags) replace external supervisor ICs; eliminates field failures from undetected supply faults. |
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; identical electrical specs and pinout; higher AMUX offset tolerance (±15 mV vs ±10 mV at TA = -40 °C to 25 °C) | Better suited for analog-critical designs requiring tighter AMUX offset across full temperature range | Select MC33978AEK if board layout allows SOICW footprint and AMUX accuracy is prioritized over thermal performance |
| MC34978AES | Same QFN-32 package; rated for -40 °C to +105 °C (vs +125 °C); identical switch detection and AMUX functionality | Targeted at interior modules with lower ambient temperature requirements (e.g., center console) | Choose MC34978AES for cost-sensitive interior applications where 105 °C rating suffices and extended temperature qualification is unnecessary |
Compared with MC33978AEK and MC34978AES, the MC33978AESR2 offers the broadest operating temperature range (-40 °C to +125 °C) in the QFN package, optimal thermal resistance (RΘJC = 2.0 °C/W), and best-in-class AMUX offset (±10 mV), making it the preferred choice for under-hood and high-reliability body controller deployments.
Availability
MC33978AESR2 is available at Aetrix Electronics and suitable for automotive door modules, steering column control units, seat position memory systems, and roof console switch panels requiring stable component supply across long production lifecycles.
Supply support for MC33978AESR2 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 ASIL-compliant mixed-signal ICs.
The MC33978AESR2 belongs to NXP's automotive system basis chip (SBC) family, designed specifically for robust, low-power switch monitoring in vehicle body electronics where reliability, ESD immunity, and parametric stability across temperature and voltage extremes are mandatory.
FAQ
What is the maximum switch input voltage range supported by the MC33978AESR2?
The MC33978AESR2 supports a switch input voltage range of -1.0 V to 36 V on all SG and SP pins. This range accommodates reverse-battery conditions, cold-crank transients down to -1.0 V, and load-dump events up to 36 V - meeting ISO 16750-2 requirements for automotive environments. Absolute maximum rating extends to -14 V (design-guaranteed) and 38 V.
How does the MC33978AESR2 implement wetting current, and what levels are available?
The MC33978AESR2 provides programmable wetting current in eight discrete levels: 2, 6, 8, 10, 12, 14, 16, or 20 mA. Each SG or SP channel can be individually configured for pulse or continuous wetting operation. Pulse duration is fixed at 20 ms ±3 ms in Normal mode, ensuring reliable contact cleaning without excessive power dissipation during switch actuation.
Can the MC33978AESR2 monitor battery voltage and die temperature simultaneously?
Yes - the MC33978AESR2 integrates both functions into its 24:1 analog multiplexer (AMUX). Battery voltage is sensed via SG5 with an internal ÷6 resistor divider (±5.0% accuracy over temperature), while die temperature is measured using an on-chip sensor whose output is routed to the AMUX pin. Both signals are accessible sequentially via SPI register reads or hardwired AMUX selection.
What are the key differences between MC33978AESR2 and MC34978AES?
The MC33978AESR2 and MC34978AES share identical QFN-32 packaging and core functionality, but differ in temperature rating: MC33978AESR2 operates from -40 °C to +125 °C, while MC34978AES is rated only to +105 °C. Both offer the same wetting current, AMUX, and SPI features - the choice depends strictly on required ambient operating temperature range.
Does the MC33978AESR2 require external components for basic operation?
Yes - the MC33978AESR2 requires an external reverse-battery protection diode on VBATP, a 100 µF bulk capacitor, and a 100 nF ceramic bypass capacitor. For ESD protection on SG/SP pins, a 100 nF capacitor with 50–100 Ω series resistor is recommended per ISO 10605. No external wetting current sources or level shifters are needed due to integrated functionality.
MC33978AESR2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 32-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Multiple Switch Detection
- Interface:
- SPI
- Voltage - Supply:
- 3V ~ 5.25V
- Supplier Device Package:
- 32-QFN-EP (5x5)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
MC33978AESR2 FAQ
1.How can I place an order for MC33978AESR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33978AESR2 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 MC33978AESR2 reliable?
The price and inventory of MC33978AESR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33978AESR2 is usually 5 days.
3.What payment methods are accepted for MC33978AESR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33978AESR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33978AESR2?
MC33978AESR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33978AESR2 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 MC33978AESR2?
For technical support, including MC33978AESR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33978AESR2 requirements.
6.How does Aetrix verify that MC33978AESR2 is sourced from the original manufacturer or authorized distributors?
All MC33978AESR2 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 MC33978AESR2 meets industry standards.
7.What is the process for return or replacement of MC33978AESR2?
All MC33978AESR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC33978AESR2, 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 MC33978AESR2 part is unused and in its original packaging.
Return procedure for MC33978AESR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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