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NXP Semiconductors MC33978AAE
- Part No.:
- MC33978AAE
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
MC33978AAE.pdf
- Description:
- SWITCH DETECTION INTERFACE, 22-S
- Quantity:
- Payment:
- Shipping:
Inventory:4,333
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Product details
Overview
MC33978AAE from NXP Semiconductors is a 22-channel automotive-grade switch detection interface IC with programmable wetting current, SPI serial interface, 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 - used in vehicle door modules, seat control units, and steering column switch interfaces.
For engineers reviewing the MC33978AAE datasheet, MC33978AAE pinout, MC33978AAE application, or MC33978AAE equivalent, this page provides verified functional identity, LQFP-EP 48-pin package mapping, confirmed 22-channel switch detection capability, wetting current programmability (2–20 mA), SPI timing compliance (≤8 MHz), and validated alternatives for automotive body electronics design.
Technical Context
The MC33978AAE implements dual-current sourcing architecture: sustain current (2.0 mA) for continuous contact verification and selectable wetting current (6–20 mA, 8 levels) for initial contact closure detection. Its internal 192 kHz LPM oscillator enables autonomous polling during low-power mode, while the 4.0 MHz main oscillator drives SPI and logic in Normal mode.
Switch state detection uses a 4.0 V comparator threshold (with ±300 mV hysteresis) referenced to VBATP; threshold drops to 0.55×VBATP below 6.0 V. The AMUX output buffers selected SG/SP channels, integrates a fixed ÷6 divider on SG5 for battery sensing, and routes die temperature (8.0 mV/°C coefficient) - all accessible via SPI-controlled channel selection or hardwired 2-/3-pin configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channels | 22 total: 14 SG-only + 8 SP (configurable as SG or SB) |
| Wetting current | Programmable 2–20 mA (8 discrete levels); enables reliable detection of high-resistance switch closures |
| Supply range | VBATP = 4.5–36 V (full parametric operation 6.0–28 V); VDDQ = 3.0–5.25 V for SPI I/O level setting |
| LPM supply current | IBATP = 30 µA, IDDQ = 10 µA - meets automotive sleep-state requirements |
| SPI interface | 3.3 V / 5.0 V compatible; max 8 MHz clock; supports CS_B/MISO/MOSI/SCLK with 100 pF load |
| AMUX functions | 24:1 analog mux with buffered output; integrated ÷6 on SG5 for battery sensing; die temp sensor (8 mV/°C) |
| 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 per NXP layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (pins 1,19,42,43) | Ground reference | Common return for logic, analog, and power domains; EP connection required for thermal performance |
| VBATP (pins 16,17) | Battery supply input | Primary power rail (4.5–36 V); requires external reverse-battery protection diode |
| VDDQ (pin 41) | Logic supply | Sets SPI I/O voltage level (3.3 V or 5.0 V); powers internal logic and MISO driver |
| CS_B, SCLK, MOSI, MISO (pins 47–42) | SPI interface | Standard 4-wire SPI with active-low chip select; MISO tri-state capable for bus sharing |
| INT_B (pin 39) | Open-drain interrupt | Asserts on switch state change; also accepts falling-edge wake-up in LPM mode |
| WAKE_B (pin 20) | Open-drain wake-up | Drives external power enable; configurable as input for system-initiated wake-up |
| AMUX (pin 40) | Analog multiplexer output | Buffered analog output for battery voltage (SG5/÷6), die temperature, or any SG/SP channel |
| SG0–SG13 (pins 6–12,25–31) | Switch-to-ground inputs | Dedicated low-side switch detection; support wetting/sustain current and LPM wake-up |
| SP0–SP7 (pins 2–5,32–35) | Programmable switch inputs | Configurable as switch-to-ground or switch-to-battery; full wetting current support |
Key Features
| Feature | Design Value |
|---|---|
| 22-channel switch detection | Reduces MCU GPIO count and external circuitry in multi-switch systems like door panels and center consoles |
| Programmable wetting current (2–20 mA) | Ensures reliable closure detection across aging contacts, corrosion, or high-resistance paths without overdriving |
| Integrated ÷6 battery monitor on SG5 | Enables accurate battery voltage measurement without external resistive dividers - saves BOM cost and PCB space |
| Die temperature sensing via AMUX | Provides real-time junction temperature data (8 mV/°C) for thermal derating or fault diagnostics |
| Low-power mode (30 µA IBATP) | Meets ISO 16750-2 and OEM sleep current budgets for always-on vehicle modules |
| Glitch filtering & debounce | Configurable 5–18 µs input glitch filter and 1.0–1.4 ms LPM debounce prevent false switch reporting |
Applications
| Door Module Switch Interface | Steering Column Control Unit |
|---|---|
|
Use Scenario: Monitoring 18+ mechanical switches (lock/unlock, window, mirror, puddle lamp) in vehicle door module with minimal MCU resource usage. IC Role / Device Role / Timing Role: Centralized switch status acquisition and SPI-based reporting; handles wetting current sequencing and LPM wake-up on keypress. Use Value: Eliminates 22 discrete pull-up resistors and GPIOs; reduces PCB area by >35% versus discrete solution; supports <30 µA sleep current. |
Use Scenario: Detecting multifunction switch states (cruise control, audio, phone) mounted on steering wheel with ESD-hardened inputs. IC Role / Device Role / Timing Role: Robust switch interface with ±15 kV contact ESD protection on SP/SG pins; AMUX reads battery voltage for low-voltage warning. Use Value: Meets AEC-Q100 Grade 1; withstands harsh automotive transients; integrated battery sensing avoids extra ADC channel. |
| Seat Position Memory System | Roof Console / Sunroof Control |
|
Use Scenario: Reading position memory buttons and seat movement limit switches in power seat ECU with fail-safe diagnostics. IC Role / Device Role / Timing Role: Monitors 12 SG inputs for seat switch positions and 4 SP inputs for memory recall buttons; reports faults via SPI register flags. Use Value: Built-in overtemperature shutdown (155 °C) prevents thermal runaway; VBATP UV/OV detection enables safe power management. |
Use Scenario: Managing sunroof open/close, tilt, and roof light controls in overhead console with minimal wiring harness impact. IC Role / Device Role / Timing Role: Interfaces 10+ switches across SG and SP banks; uses Polling mode to reduce average current while maintaining responsiveness. Use Value: Programmable polling interval (64 ms default) cuts average current to <1 µA; AMUX validates battery health before executing motor commands. |
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 feature set; lower pin count limits SG/SP allocation (14 SG + 6 SP) | Preferred for space-constrained PCBs where 32-pin SOIC footprint is acceptable; same -40 °C to +125 °C rating | Select when board layout favors SOIC package or when fewer than 22 channels are needed; no firmware changes required |
| MC34978AES | QFN 32-pin package; operates at -40 °C to +105 °C (not 125 °C); identical switch detection and AMUX functionality | Suitable for interior modules with lower ambient temperature exposure (e.g., infotainment bezels, HVAC controls) | Choose for cost-sensitive interior applications where extended temperature range is unnecessary; verify thermal margin in final enclosure |
Compared with MC33978AAE, MC33978AEK offers identical functionality in a smaller SOIC package but with reduced channel count, while MC34978AES trades junction temperature rating for QFN miniaturization - both require no SPI register reconfiguration but differ in thermal robustness and physical integration.
Availability
MC33978AAE is available at Aetrix Electronics and suitable for automotive door modules, seat control units, and steering column switch interfaces requiring stable component supply, AEC-Q100 qualification, and long-term production continuity.
Supply support for MC33978AAE 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 MC33978 product line was designed specifically for automotive body electronics to consolidate mechanical switch monitoring, reduce system-level BOM cost, and meet stringent ISO 16750 and AEC-Q100 reliability requirements.
FAQ
What is the operating voltage range for MC33978AAE's VBATP supply?
The MC33978AAE supports VBATP from 4.5 V to 36 V, with full parametric operation guaranteed between 6.0 V and 28 V. Below 6.0 V, certain parameters degrade - including switch detection threshold (reduced to 0.55×VBATP) and wetting current headroom - but the device remains functional down to 4.5 V per datasheet Rev. 10.
How does MC33978AAE handle switch debouncing in Low-power mode?
The MC33978AAE applies a fixed 1.0–1.4 ms additional debounce time in Low-power mode after detecting an edge, preventing false triggers from noise or mechanical bounce. This is independent of the 5–18 µs glitch filter applied in Normal mode and is automatically enabled during LPM wake-up events.
Can MC33978AAE measure battery voltage directly, and how accurate is it?
Yes - MC33978AAE measures battery voltage via SG5 input configured with an internal ÷6 resistor divider. Accuracy is ±5.0% over full temperature range and ±3.0% over 6.0–28 V VBATP range. Calibration at 12 V and 25 °C improves accuracy further, as documented in Figure 6 of the datasheet.
What SPI timing parameters define maximum communication speed for MC33978AAE?
The MC33978AAE supports SPI transfer frequencies up to 8.0 MHz. Key timing constraints include SCLK period ≥160 ns, setup time ≥16 ns, hold time ≥20 ns, and MISO access time ≤116 ns (with 100 pF load). These values are specified at TA = -40 °C to +125 °C and ensure robust operation across automotive temperature extremes.
Does MC33978AAE provide thermal protection, and what are the trip points?
Yes - MC33978AAE includes thermal shutdown at 155 °C (typical) with 5–15 °C hysteresis. A temperature warning flag activates at 105–135 °C, allowing the host MCU to initiate derating or diagnostics before shutdown. Both thresholds are characterized per AEC-Q100 and apply across the full -40 °C to +125 °C ambient range.
MC33978AAE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 48-LQFP Exposed Pad
- Packaging:
- Tray
- 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
MC33978AAE FAQ
1.How can I place an order for MC33978AAE through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33978AAE 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 MC33978AAE reliable?
The price and inventory of MC33978AAE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33978AAE is usually 5 days.
3.What payment methods are accepted for MC33978AAE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33978AAE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33978AAE?
MC33978AAE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33978AAE 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 MC33978AAE?
For technical support, including MC33978AAE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33978AAE requirements.
6.How does Aetrix verify that MC33978AAE is sourced from the original manufacturer or authorized distributors?
All MC33978AAE 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 MC33978AAE meets industry standards.
7.What is the process for return or replacement of MC33978AAE?
All MC33978AAE units undergo pre-shipment inspection (PSI). If there is an issue with MC33978AAE, 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 MC33978AAE part is unused and in its original packaging.
Return procedure for MC33978AAE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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