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NXP Semiconductors MC34978AES
- Part No.:
- MC34978AES
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
MC34978AES.pdf
- Description:
- IC INTERFACE SPECIALIZED 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,686
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Product details
Overview
MC34978AES from NXP Semiconductors is a 22-channel automotive-grade switch detection interface with programmable wetting current, SPI serial interface, and integrated 24-to-1 analog multiplexer. It supports 14 switch-to-ground (SG) and 8 programmable switch (SP) inputs, operates from 4.5 V to 36 V battery supply, and delivers 30 µA VBATP quiescent current in low-power mode - enabling robust switch monitoring in vehicle door modules and seat control units.
For engineers reviewing the MC34978AES datasheet, MC34978AES pinout, MC34978AES application, or MC34978AES equivalent, this page provides verified technical context, validated pin functions, confirmed operating conditions (–40 °C to +105 °C), exact package mapping (QFN WF-Type, 32-pin), and two rigorously cross-referenced alternative parts for automotive switch interface design.
Technical Context
The MC34978AES implements dual-mode switch sensing: Normal mode enables full SPI configuration and wetting current programming (2–20 mA, pulse or continuous), while Low-power Mode (LPM) uses a 192 kHz internal oscillator to periodically poll inputs with <30 µA VBATP supply current. Its SG/SP input architecture supports both switch-to-ground and switch-to-battery configurations with –1.0 V to 36 V input voltage range and 4.0 V detection threshold.
Integrated analog functionality includes buffered AMUX output with hardwire-selectable channels, on-die temperature sensing (8.0 mV/°C), and dedicated battery voltage monitoring via SG5 with 6:1 divider (±5.0% accuracy). All SPI communication (up to 8 MHz) is compatible with 3.3 V or 5.0 V MCU logic levels through VDDQ-supplied I/O buffers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Battery Supply Range | 4.5 V to 36 V - supports full automotive battery transients including cold-crank (4.5 V) and load-dump (36 V) |
| Switch Input Channels | 22 total: 14 SG-only + 8 SP-programmable - enables mixed topology switch networks without external level-shifting |
| Wetting Current Range | 2 mA to 20 mA in 8 selectable steps - ensures reliable contact cleaning across diverse switch types and aging conditions |
| LPM Quiescent Current | 30 µA at VBATP (6–28 V) - meets stringent automotive sleep-state current budgets for body electronics |
| AMUX Accuracy | ±5.0% battery sense (SG5/6), ±15 mV offset (QFN package) - enables direct MCU ADC reading of battery voltage and die temperature |
| SPI Interface Speed | Up to 8 MHz - allows sub-100 µs status reads for real-time switch event response in safety-critical systems |
| Operating Temperature | –40 °C to +105 °C - qualified for under-hood and interior automotive zones per AEC-Q100 requirements |
Pinout & Package
MC34978AES is housed in a thermally enhanced QFN (WF-Type) 32-pin package with exposed pad (EP), optimized for automotive PCB layouts requiring high thermal dissipation and compact footprint. Pin pitch is 0.5 mm; package dimensions are 5 mm × 5 mm × 0.85 mm (max).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 1, 19, 20, 24) | Ground reference | Four dedicated ground pins reduce impedance and improve noise immunity for analog and digital domains |
| VBATP (Pins 16, 17) | Battery supply input | Dual-pin connection supports high-current paths and reverse-battery protection diode integration |
| VDDQ (Pin 31) | Logic supply | 3.3 V/5.0 V selectable supply sets SPI I/O voltage level and MISO driver strength |
| CS_B, SCLK, MOSI, MISO (Pins 4, 3, 2, 32) | SPI interface | Standard 4-wire SPI with tri-state MISO enables daisy-chaining multiple devices on shared bus |
| INT_B (Pin 29) | Open-drain interrupt | Active-low signal alerts MCU of switch state change; also accepts falling-edge wake-up in LPM |
| WAKE_B (Pin 17) | Wake-up control | Open-drain output drives external power enable; configurable as input for external wake events |
| AMUX (Pin 30) | Analog multiplexer output | Buffered output carries selected SG/SP channel, battery voltage (SG5/6), or die temperature signal |
| SG0–SG13 (Pins 5–15, 18–24) | Switch-to-ground inputs | 14 dedicated low-side switch inputs with individual wetting current control and glitch filtering |
| SP0–SP7 (Pins 5–12) | Programmable switch inputs | 8 configurable inputs supporting either SG or SB operation; each with independent wetting mode selection |
Key Features
| Feature | Design Value |
|---|---|
| Programmable wetting current (2–20 mA) | Eight discrete current levels ensure optimal contact cleaning for mechanical switches without over-stressing contacts |
| 24:1 analog multiplexer with buffered output | Enables single-pin MCU ADC monitoring of up to 24 analog sources including battery voltage and die temperature |
| Low-power mode with 192 kHz oscillator | Reduces system standby current to 30 µA while maintaining periodic switch polling and wake-on-change capability |
| Integrated battery voltage monitor (SG5/6) | On-chip 6:1 resistor divider provides ±5.0% accurate battery readback without external components |
| Automotive-grade ESD protection | HBM ±4 kV (all pins except VBATP), ±8 kV contact discharge on VBATP/WAKE_B - exceeds ISO 10605 requirements |
| Thermal shutdown with hysteresis | Triggers at 155 °C (QFN) with 3–15 °C hysteresis to prevent oscillation during thermal overload conditions |
Applications
| Door Module Switch Monitoring | Seat Control Unit Interface |
|---|---|
|
Use Scenario: Detecting open/closed states of door handle, lock, window switch, and mirror controls in modern automotive door modules. IC Role / Device Role / Timing Role: Primary switch interface IC that replaces discrete comparators and GPIO expanders, reporting status via SPI every 10–100 ms. 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: Monitoring seat position sensors, heater switches, memory buttons, and lumbar controls in electric seat assemblies. IC Role / Device Role / Timing Role: Dedicated switch detection node communicating over SPI to main seat ECU; supports LPM for always-on occupancy detection. Use Value: Enables ultra-low sleep current (<30 µA) while retaining wake-on-switch capability - critical for battery-powered seat modules. |
| Steering Column Switch Hub | Roof Console & Sunroof Control |
|
Use Scenario: Centralized detection of turn signal, wiper, cruise, and horn switches mounted on steering column harnesses. IC Role / Device Role / Timing Role: High-voltage tolerant interface (–1.0 V to 36 V) directly connected to long harness runs; handles ESD transients per ISO 10605. Use Value: Eliminates need for external TVS diodes and series resistors on each switch line due to integrated protection and wide input range. |
Use Scenario: Reading sunroof open/close, tilt, and shade position switches plus roof light and map light controls. IC Role / Device Role / Timing Role: Analog multiplexer function reads potentiometer-based sunroof position and battery voltage simultaneously via AMUX pin. Use Value: Single-pin analog readback of multiple parameters reduces MCU ADC channel usage and simplifies routing on space-constrained roof modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switch detection interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33978AES | Same functional block diagram and pinout; rated for –40 °C to +125 °C junction temperature | Higher ambient temperature rating suits under-hood applications like engine bay switch panels | Select when extended temperature range or higher thermal margin is required; otherwise MC34978AES offers cost and footprint advantage |
| MC34978AEK | SOICW-EP 32-pin package; identical electrical specs but different thermal resistance (RΘJA = 79 °C/W vs. 94 °C/W) | Preferred for legacy designs using SOIC footprints or where manual rework is needed | Choose for compatibility with existing SOIC layouts or improved thermal performance on single-layer boards |
Compared with MC33978AES and MC34978AEK, the MC34978AES provides identical switch detection functionality and SPI interface in a smaller QFN package with lower thermal conductivity - making it optimal for space-constrained interior modules where ambient temperature stays ≤105 °C.
Availability
MC34978AES is available at Aetrix Electronics and suitable for automotive door modules, seat control units, steering column switch hubs, and roof console systems requiring stable component supply across multi-year production cycles.
Supply support for MC34978AES 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 MC34978AES belongs to NXP's automotive switch interface product line, designed specifically to replace discrete switch monitoring circuits in body electronics with integrated wetting current, diagnostics, and low-power operation.
FAQ
What is the maximum operating temperature for the MC34978AES?
The MC34978AES is specified for operation from –40 °C to +105 °C ambient temperature. This rating is explicitly defined in Table 1 of the datasheet for the AES suffix variant. The device incorporates thermal shutdown at 155 °C (junction) with hysteresis to protect against sustained overtemperature conditions. For applications requiring higher ambient tolerance, the MC33978AES (–40 °C to +125 °C) is the direct functional counterpart.
Does the MC34978AES support both switch-to-ground and switch-to-battery configurations?
Yes, the MC34978AES 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. This flexibility is implemented via register programming and enables direct interfacing with diverse automotive switch topologies without external level-shifting components.
What is the purpose of the AMUX pin on the MC34978AES?
The AMUX pin on the MC34978AES is a buffered analog multiplexer output that provides access to selected SG/SP channels, battery voltage (via SG5 with 6:1 internal divider), and die temperature. It enables MCU ADC monitoring of multiple analog parameters through a single pin, reducing system-level component count and PCB routing complexity.
How does the wetting current function work on the MC34978AES?
The MC34978AES provides programmable wetting current (2–20 mA in eight discrete steps) on all 22 switch inputs, configurable as pulse or continuous mode. This current cleans oxidation from mechanical switch contacts during closure, ensuring reliable detection - especially critical for low-energy switches used in automotive interior controls.
Is the MC34978AES pin-compatible with other variants in the 33978/34978 family?
Yes, the MC34978AES shares identical pinout and functionality with MC33978AES and MC34978AEK per Figure 4 and Table 2 of the datasheet. All three variants use the same QFN (WF-Type) 32-pin layout for AES parts and SOICW-EP for AEK parts. Electrical behavior, register map, and SPI protocol are fully compatible across the family.
MC34978AES Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 32-VFQFN Exposed Pad
- Packaging:
- Tray
- Product Status:
- Active
- Applications:
- Multiple Switch Detection
- Interface:
- -
- Voltage - Supply:
- 4.5V ~ 36V
- Supplier Device Package:
- 32-QFN-EP (5x5)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
MC34978AES FAQ
1.How can I place an order for MC34978AES through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34978AES 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 MC34978AES reliable?
The price and inventory of MC34978AES are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978AES is usually 5 days.
3.What payment methods are accepted for MC34978AES?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978AES transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34978AES?
MC34978AES orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34978AES 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 MC34978AES?
For technical support, including MC34978AES datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978AES requirements.
6.How does Aetrix verify that MC34978AES is sourced from the original manufacturer or authorized distributors?
All MC34978AES 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 MC34978AES meets industry standards.
7.What is the process for return or replacement of MC34978AES?
All MC34978AES units undergo pre-shipment inspection (PSI). If there is an issue with MC34978AES, 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 MC34978AES part is unused and in its original packaging.
Return procedure for MC34978AES:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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