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NXP Semiconductors MC34978AEKR2
- Part No.:
- MC34978AEKR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-SSOP (0.295", 7.50mm Width) Exposed Pad
- Datasheet:
-
MC34978AEKR2.pdf
- Description:
- IC INTERFACE SPECIALIZED 32SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,639
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Product details
Overview
MC34978AEKR2 from NXP Semiconductors is a 22-channel 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 automotive-grade voltage range (4.5 V–36 V), delivers buffered AMUX output for battery/temperature sensing, and supports Normal, Low-power (LPM), and Polling modes. Used in vehicle door modules, seat control units, and steering column switch interfaces.
For engineers reviewing the MC34978AEKR2 datasheet, MC34978AEKR2 pinout, MC34978AEKR2 application, or MC34978AEKR2 equivalent, this page provides verified technical context, exact pin functions, real-world use scenarios, validated alternatives, and supply-ready availability details - all grounded in NXP's Rev. 10 product data sheet dated 20 August 2024.
Technical Context
The MC34978AEKR2 implements dual-mode switch detection logic: SG inputs operate with fixed 4.0 V threshold (degraded to 0.55×VBATP below 6.0 V), while SP inputs support configurable switch-to-battery (SB) or switch-to-ground (SG) topology. Wetting current is programmable across eight levels (2–20 mA) in pulse or continuous mode, with ±10% tolerance for SG channels and ±20% for SB channels.
Its analog multiplexer routes 22 SG/SP inputs plus internal battery divider (SG5/6) and die temperature sensor to the AMUX pin, with 10 mV offset spec (SOICW package), 8.0 mV/°C temp coefficient, and ±5.0% battery sense accuracy. LPM draws only 30 μA (VBATP) and 10 μA (VDDQ), enabled by a dedicated 192 kHz oscillator with ±15% tolerance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Channels | 22 total: 14 SG + 8 SP; supports SB/SG configuration per SP pin |
| Wetting Current Range | 2 mA to 20 mA in 8 discrete steps; pulse or continuous operation |
| Supply Voltage Range | VBATP: 4.5 V–36 V (functional); 6.0 V–28 V (full parametric) |
| LPM Supply Current | IBATP = 30 μA, IDDQ = 10 μA - enables <100 μA system sleep power |
| AMUX Accuracy | Battery sense (SG5/6): ±5.0% full-range accuracy; temp sensor: 8.0 mV/°C |
| SPI Interface | 3.3 V / 5.0 V compatible; max 8 MHz clock; 116 ns MISO access time |
| Operating Temp | -40 °C to +105 °C - qualified for passenger compartment applications |
Pinout & Package
MC34978AEKR2 uses SOICW-EP 32-pin package (exposed pad), RoHS-compliant, with thermal resistance RΘJA = 79 °C/W (natural convection).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SP0–SP7 | Programmable Switch Inputs | Configurable as switch-to-battery (SB) or switch-to-ground (SG); support wetting current selection |
| SG0–SG13 | Switch-to-Ground Inputs | Dedicated low-threshold (4.0 V) inputs; 14 channels with sustain/wetting current control |
| VBATP | Battery Supply Input | Primary power rail (4.5–36 V); requires external reverse-battery protection diode |
| WAKE_B | Open-Drain Wake-Up Output | Controls external power enable; also accepts falling-edge wake-up in LPM |
| INT_B | Open-Drain Interrupt Output | Asserts on switch state change; double-function input for LPM wake-up |
| AMUX | Analog Multiplexer Output | Buffered output for SG/SP channels, battery voltage (÷6), and die temperature |
| CS_B, SCLK, MOSI, MISO | SPI Interface Signals | Standard 4-wire SPI at 3.3 V/5.0 V logic; CS_B active-low with 125 kΩ internal pull-up |
| VDDQ | Logic Supply | 3.3 V/5.0 V supply setting SPI I/O voltage level and buffer thresholds |
| GND / EP | Ground / Exposed Pad | Logic/analog ground reference; exposed pad must be connected to system GND |
Key Features
| Feature | Design Value |
|---|---|
| 24:1 Analog Multiplexer | Routes 22 switch inputs + battery divider (SG5/6) + die temp sensor to single AMUX pin with buffered output |
| Programmable Wetting Operation | Selectable pulse (20 ms ON) or continuous wetting current per channel - prevents contact oxidation in harsh environments |
| Low-Power Mode (LPM) | 30 μA VBATP current enables >1-year battery life in always-on vehicle modules without compromising wake responsiveness |
| Integrated Battery & Temp Sensing | SG5 configured as ÷6 battery monitor (±5% accuracy); die temp sensor outputs via AMUX (8.0 mV/°C linear slope) |
| Robust Switch Input Protection | SG/SP pins rated -1.0 V to +36 V; ±15 kV CDM ESD rating on protected pins; supports external 100 nF caps + series resistors |
Applications
| Door Module Switch Interface | Seat Control Unit |
|---|---|
Use Scenario: Monitoring 12+ mechanical switches (lock, window, mirror, memory) on vehicle door panels with long harness runs. IC Role / Device Role / Timing Role: Primary switch detection interface; converts discrete switch closures into SPI-readable status registers with glitch filtering and wetting current control. Use Value: Eliminates need for discrete pull-ups and external analog mux; reduces BOM count by 7+ components per module while enabling contact reliability over 100k cycles. | Use Scenario: Detecting position switches (forward/back, recline, lumbar, heating) in driver/passenger seats with shared battery rail and space-constrained PCB layout. IC Role / Device Role / Timing Role: Centralized switch monitor with integrated battery voltage monitoring (via SG5) and die temperature reporting - critical for thermal derating of seat heater drivers. Use Value: Single-chip solution replaces discrete comparators, muxes, and voltage dividers; AMUX output allows MCU to sample battery health and IC junction temp without extra ADC channels. |
| Steering Column Switch Hub | Roof Console / Overhead Control Panel |
Use Scenario: Aggregating 8–10 multifunction switches (cruise, audio, phone, voice) mounted on rotating steering column with EMI-prone cabling. IC Role / Device Role / Timing Role: High-immunity switch detector with programmable wetting current and 1.2 ms LPM debounce - suppresses false triggers from vibration and harness noise. Use Value: Meets ISO 11452-4 EMI immunity requirements without added shielding; wetting current ensures reliable detection after years of infrequent use. | Use Scenario: Managing dome light, sunroof, map light, and garage door opener switches in overhead console with limited board area and shared 12 V supply. IC Role / Device Role / Timing Role: Low-quiescent-current (30 μA) switch monitor enabling "always-on" functionality while meeting OEM sleep current budgets (<100 μA). Use Value: Enables instant wake from LPM on any switch press; eliminates need for separate wake controller or high-side load switch. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switch detection interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33978AEKR2 | Same SOICW-EP 32-pin package; identical pinout and register map; operates to +125 °C ambient | Targeted for under-hood or high-temp cabin zones (e.g., HVAC control) | Select when extended temperature range (-40 °C to +125 °C) is required and thermal margin exceeds 20 °C |
| MC34978AESR2 | QFN (WF-Type) 32-pin; same electrical specs; no exposed pad thermal path to PCB | Better suited for space-constrained layouts where SOICW footprint is prohibitive | Choose for compact designs needing lower profile and improved thermal coupling to PCB copper |
Compared with MC33978AEKR2 and MC34978AESR2, the MC34978AEKR2 offers identical functionality in the SOICW-EP package but with a -40 °C to +105 °C operating range - making it optimal for passenger compartment modules where cost-sensitive packaging and proven manufacturability outweigh extreme temperature needs.
Availability
MC34978AEKR2 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-aligned reliability, and long-term production continuity.
Supply support for MC34978AEKR2 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 MC34978AEKR2 belongs to NXP's automotive switch interface product line, engineered specifically for robust, low-power detection of mechanical switches in vehicle body electronics - emphasizing contact reliability, ESD resilience, and seamless SPI integration with microcontrollers.
FAQ
What is the maximum switch input voltage range supported by the MC34978AEKR2?
The MC34978AEKR2 supports a switch input voltage range of -1.0 V to +36 V on all SG and SP pins. This wide range accommodates negative transients (e.g., load dump recovery) and positive spikes common in 12 V automotive systems. The device includes internal protection circuitry and is rated for ±15 kV CDM ESD on protected pins when used with recommended external 100 nF capacitors and series resistors.
Does the MC34978AEKR2 support both switch-to-ground and switch-to-battery configurations?
Yes, the MC34978AEKR2 supports both configurations: 14 dedicated SG inputs and 8 programmable SP inputs that can be configured as either switch-to-ground (SG) or switch-to-battery (SB) via register settings. SB mode uses a higher sustain current (2.2 mA typical) and different wetting current tolerance (±20%), while SG mode offers tighter matching (±10%) and lower threshold detection (4.0 V nominal).
How does the AMUX output function in the MC34978AEKR2, and what signals can it deliver?
The AMUX output in the MC34978AEKR2 is a buffered analog multiplexer output that sequentially delivers signals from any of the 22 SG/SP inputs, the internal battery voltage divider (SG5/6, ÷6 ratio), or the die temperature sensor. Selection is controlled via SPI register writes or hardwired pins (SG1–SG3). The output has ±10 mV offset (SOICW package), 8.0 mV/°C temp coefficient, and ±5.0% battery sense accuracy over temperature.
What are the key differences between Normal mode and Low-power mode (LPM) in the MC34978AEKR2?
In Normal mode, the MC34978AEKR2 actively supplies wetting/sustain current to all enabled switch inputs and reports status changes via INT_B with <18.5 µs delay. In LPM, it disables most circuitry, draws only 30 µA (VBATP) and 10 µA (VDDQ), and performs periodic polling (configurable interval) - waking fully only on interrupt or external WAKE_B/INT_B edge. LPM uses a dedicated 192 kHz oscillator with ±15% tolerance.
Is the MC34978AEKR2 pin-compatible with other variants in the 33978/34978 family?
Yes, the MC34978AEKR2 is pin-compatible with MC33978AEKR2 and MC34978AESR2 within the same package type: all SOICW-EP 32-pin variants share identical pinout, electrical behavior, and register mapping. However, MC34978AEKR2 and MC33978AEKR2 differ in temperature grade (-40 °C to +105 °C vs. -40 °C to +125 °C), and MC34978AESR2 uses QFN packaging with distinct thermal and mounting characteristics.
MC34978AEKR2 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:
- -
- Voltage - Supply:
- 4.5V ~ 36V
- Supplier Device Package:
- 32-SOIC-EP
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
MC34978AEKR2 FAQ
1.How can I place an order for MC34978AEKR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34978AEKR2 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 MC34978AEKR2 reliable?
The price and inventory of MC34978AEKR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978AEKR2 is usually 5 days.
3.What payment methods are accepted for MC34978AEKR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978AEKR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34978AEKR2?
MC34978AEKR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34978AEKR2 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 MC34978AEKR2?
For technical support, including MC34978AEKR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978AEKR2 requirements.
6.How does Aetrix verify that MC34978AEKR2 is sourced from the original manufacturer or authorized distributors?
All MC34978AEKR2 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 MC34978AEKR2 meets industry standards.
7.What is the process for return or replacement of MC34978AEKR2?
All MC34978AEKR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC34978AEKR2, 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 MC34978AEKR2 part is unused and in its original packaging.
Return procedure for MC34978AEKR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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