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NXP Semiconductors MC34978EKR2
- Part No.:
- MC34978EKR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-SSOP (0.295", 7.50mm Width) Exposed Pad
- Datasheet:
-
MC34978EKR2.pdf
- Description:
- IC INTERFACE SPECIALIZED 32SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,980
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Product details
Overview
MC34978EKR2 from NXP Semiconductors is a 22-channel automotive-grade switch detection interface IC with programmable wetting current, integrated 24:1 analog multiplexer (AMUX), battery/temperature monitoring, and SPI communication. It operates from 4.5 V to 36 V, supports Normal and Low-power modes (IBATP ≤ 40 µA in LPM), and interfaces directly with 3.3 V/5.0 V MCUs for vehicle HVAC, lighting, and gateway I/O control.
For engineers reviewing the MC34978EKR2 datasheet, MC34978EKR2 pinout, MC34978EKR2 application, or MC34978EKR2 equivalent, this page delivers verified technical context, exact pin functions, real-world use scenarios, and validated alternative parts - all grounded in NXP's MC33978/MC34978 documentation and package-specific validation for the SOICW-EP 32-pin variant.
Technical Context
The MC34978EKR2 implements dual-mode operation: Normal mode enables full configuration, switch polling, and programmable wetting currents (2–20 mA) across eight SPx (switch-to-battery/ground) and fourteen SGx (switch-to-ground) inputs; Low-power mode reduces IBATP to ≤40 µA while maintaining wake-on-change capability via INT_B or WAKE_B. Its internal 192 kHz oscillator drives LPM timing with ±15% tolerance.
It integrates a buffered AMUX output (VDDQ-referenced, ±10 mV offset in EK package) that sequentially routes up to 24 analog inputs-including battery voltage (via SG5 ÷6), die temperature (8.0 mV/°C), and switch states-to the MCU. All switch inputs tolerate −1.0 V to 36 V, with VICTHR = 4.0 V (±0.3 V) and 100–300 mV hysteresis in LPM for robust contact detection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channels | 22 switch inputs: 8 programmable (SP0–SP7), 14 switch-to-ground (SG0–SG13) |
| Wetting current | Selectable 2, 6, 8, 10, 12, 14, 16, or 20 mA per channel - enables reliable contact cleaning in harsh environments |
| Supply range | VBATP: 4.5 V–36 V functional; 6.0 V–28 V full parametric - supports 12 V/24 V automotive batteries with reverse protection |
| LPM supply current | IBATP ≤ 40 µA at 6–28 V - enables multi-year battery life in always-on vehicle modules |
| SPI interface | 3.3 V/5.0 V compatible, up to 8 MHz - eliminates level-shifting for common microcontrollers |
| AMUX accuracy | Battery sense (SG5÷6): ±5.0% over temp; Temp coefficient: 8.0 mV/°C - enables direct MCU-based thermal/battery diagnostics |
| Interrupt & wake | Active-low open-drain INT_B with <110 µs pulse; WAKE_B supports external enable control - ensures deterministic system wake-up |
Pinout & Package
MC34978EKR2 uses the SOICW-EP (exposed pad) 32-pin package (98ASA10556D), with thermal pad (EP) tied to GND for enhanced power dissipation and noise immunity. Pin numbering follows standard SOICW layout with pins 1–16 on top row (left to right), 17–32 on bottom row (right to left).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Ground reference | Primary logic/analog ground; exposed pad (EP) must be connected to same net for thermal and EMI performance |
| MOSI (Pin 2) | SPI data input | Accepts 3.3 V/5.0 V command bytes from MCU; internal pull-down ensures safe state during reset |
| SCLK (Pin 3) | SPI clock input | Drives internal shift register; max 8 MHz rate supports fast configuration and status reads |
| CS_B (Pin 4) | SPI chip select | Active-low enable; falling edge initiates transaction; internal 40–270 kΩ pull-up prevents spurious activation |
| SP0–SP7 (Pins 5–8, 16–17, 29–30) | Programmable switch inputs | Configurable as pull-up/pull-down; support wetting current programming for each channel independently |
| SG0–SG13 (Pins 9–15, 18–24) | Switch-to-ground inputs | Dedicated low-side sensing; LPM wake threshold set to 100–300 mV for ultra-low-current detection |
| VBATP (Pin 16) | Battery supply input | 4.5–36 V tolerant; requires external reverse-battery diode; powers internal regulators and wetting circuits |
| WAKE_B (Pin 17) | Open-drain wake output/input | Drives external PMIC enable; also accepts falling-edge wake request from external sources |
| INT_B (Pin 29) | Open-drain interrupt output | Asserts on any switch state change; <110 µs pulse width ensures reliable MCU edge capture |
| AMUX (Pin 30) | Analog multiplexer output | Buffered, rail-to-rail output of selected channel (battery, temp, or switch); ±10 mV offset in EK package |
| VDDQ (Pin 31) | I/O supply voltage | Sets SPI logic levels and MISO drive strength; 3.0–5.25 V range matches MCU I/O domains |
| MISO (Pin 32) | SPI data output | Tri-state capable; 3.3 V/5.0 V compatible; 116 ns access time enables high-speed status polling |
Key Features
| Feature | Design Value |
|---|---|
| Independent wetting current per channel | Eight selectable levels (2–20 mA) per SP/SG input - eliminates need for external current sources in multi-switch panels |
| Integrated battery & temperature monitor | Direct AMUX access to SG5÷6 battery voltage and on-die temp sensor (8.0 mV/°C) - removes external ADC and signal conditioning |
| Low-power mode with wake-on-change | IBATP ≤ 40 µA + hardware-interrupt wake (INT_B/WAKE_B) - meets automotive ASAM/ISO 16750 sleep-current requirements |
| Robust switch input tolerance | −1.0 V to 36 V operating range with ±2 µA leakage - withstands load dump, jump-start, and negative transients without protection diodes |
| Glitch-filtered & debounced inputs | 5–18 µs glitch filter (Normal), 1.0–1.4 ms LPM debounce - rejects EMI-induced false triggers in noisy vehicle environments |
Applications
| Automotive HVAC Control Panel | Industrial PLC Input Module |
|---|---|
|
Use Scenario: Detecting button presses and rotary encoder positions on a climate control panel with 18 physical switches and 4 analog sensors. IC Role / Device Role / Timing Role: MC34978EKR2 scans all 22 inputs via SPI, applies 10 mA wetting current to buttons, and routes battery voltage and temperature to AMUX for health monitoring. Use Value: Reduces MCU GPIO count by 22 pins; eliminates 22 external pull resistors and 2 current sources; enables single-wire diagnostics via AMUX. |
Use Scenario: Monitoring 12 machine safety interlocks and 10 operator panel switches in a factory automation cabinet. IC Role / Device Role / Timing Role: MC34978EKR2 operates in LPM between polls, wakes on any interlock break, and reports status via SPI to the PLC CPU. Use Value: Achieves <40 µA standby current - extends backup battery life to >5 years; built-in debounce prevents nuisance trips from relay chatter. |
| Vehicle Central Gateway I/O Expansion | Smart Lighting Control System |
|
Use Scenario: Adding 22 discrete I/O points (door locks, mirror controls, seat switches) to an existing CAN gateway without redesigning the main PCB. IC Role / Device Role / Timing Role: MC34978EKR2 acts as a dedicated I/O concentrator, translating switch events into SPI packets for the gateway MCU to forward over CAN. Use Value: Offloads I/O management from the main processor; supports hot-plug detection via WAKE_B; maintains ASIL-B readiness with diagnostic registers. |
Use Scenario: Managing 16 dimmer switches and 6 occupancy sensor inputs in a commercial LED lighting controller. IC Role / Device Role / Timing Role: MC34978EKR2 supplies 6 mA wetting current to mechanical dimmers, reads ambient light via AMUX-connected photodiode, and signals changes via INT_B. Use Value: Enables zero-crossing sync for TRIAC dimming; AMUX linearity (±5% battery sense) allows precise power budgeting per fixture. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switch detection interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33978EK | Same SOICW-EP 32-pin package; wider operating temperature (−40°C to +125°C vs. −40°C to +105°C) | Required for under-hood or engine bay placement where junction temperatures exceed 105°C | Select MC33978EK when ambient temperature exceeds 105°C; otherwise MC34978EKR2 offers identical functionality at lower cost. |
| MC34978AES | QFN (WF-Type) 32-pin package; same temperature range; 12°C/W RΘJA vs. 79°C/W for SOICW-EP | Better thermal performance in space-constrained layouts; requires reflow-compatible PCB design | Choose MC34978AES for compact, thermally demanding designs; MC34978EKR2 suits legacy through-hole or wave-soldered assemblies. |
Compared with MC33978EK and MC34978AES, the MC34978EKR2 provides optimal balance of industrial temperature margin, SOICW-EP manufacturability, and thermal performance for cabin-mounted automotive and industrial I/O modules - avoiding over-specification while ensuring long-term reliability.
Availability
MC34978EKR2 is available at Aetrix Electronics and suitable for automotive HVAC systems, industrial PLC input modules, vehicle central gateway expansions, and smart lighting control systems requiring stable component supply, automotive qualification, and long-lifecycle support.
Supply support for MC34978EKR2 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 MC34978EKR2 belongs to NXP's SMARTMOS switch detection interface product line, engineered specifically for high-reliability, low-power vehicle body electronics and industrial control systems requiring robust switch monitoring and integrated diagnostics.
FAQ
What is the operating temperature range for the MC34978EKR2?
The MC34978EKR2 is rated for operation from −40 °C to +105 °C ambient temperature. This range is validated per AEC-Q100 stress testing and supports placement in passenger cabin modules, instrument clusters, and industrial control enclosures - though it is not qualified for under-hood locations exceeding 105 °C, where the MC33978EK variant is required. The device includes thermal shutdown at 155 °C with 3–15 °C hysteresis.
How does the MC34978EKR2 handle switch debouncing and EMI rejection?
The MC34978EKR2 incorporates two-stage filtering: a 5–18 µs digital glitch filter in Normal mode and a 1.0–1.4 ms hardware debounce timer in Low-power mode. These are applied per-input and operate independently of the MCU, eliminating software overhead. Combined with ±2 µA input leakage and −1.0 V to 36 V input tolerance, the MC34978EKR2 rejects EMI-induced false triggers in automotive and industrial noise environments without external RC networks.
Can the MC34978EKR2 monitor battery voltage and temperature simultaneously?
Yes. The MC34978EKR2 integrates both functions on the AMUX pin: battery voltage is measured via SG5 configured as a ÷6 divider (±5.0% accuracy), and die temperature is reported as an 8.0 mV/°C analog output. The AMUX sequentially routes these and other inputs (e.g., SP/SG states) to the same output pin, allowing the MCU to read them in sequence using SPI commands - no external sensors or ADCs are needed.
What is the minimum wetting current supported by the MC34978EKR2, and how is it programmed?
The MC34978EKR2 supports a minimum wetting current of 2 mA, selectable via SPI register configuration for each SPx or SGx channel. Wetting current levels are programmable in eight discrete steps: 2, 6, 8, 10, 12, 14, 16, and 20 mA. This is implemented using on-chip current sources with ±10% matching between channels, enabling consistent contact cleaning across all 22 inputs without external components.
Does the MC34978EKR2 require external protection circuitry for VBATP?
Yes. Although the MC34978EKR2 tolerates up to 40 V on VBATP, NXP specifies mandatory external reverse-battery protection: a series diode (VF = 0.6–1.0 V) between the battery and VBATP, plus a 100 µF bulk capacitor and 100 nF bypass capacitor. This protects against jump-start transients and reverse polarity - the IC itself does not include integrated reverse-voltage protection.
MC34978EKR2 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:
- Obsolete
- Applications:
- Multiple Switch Detection
- Interface:
- -
- Voltage - Supply:
- 4.5V ~ 36V
- Supplier Device Package:
- 32-SOIC-EP
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
MC34978EKR2 FAQ
1.How can I place an order for MC34978EKR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34978EKR2 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 MC34978EKR2 reliable?
The price and inventory of MC34978EKR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978EKR2 is usually 5 days.
3.What payment methods are accepted for MC34978EKR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978EKR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34978EKR2?
MC34978EKR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34978EKR2 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 MC34978EKR2?
For technical support, including MC34978EKR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978EKR2 requirements.
6.How does Aetrix verify that MC34978EKR2 is sourced from the original manufacturer or authorized distributors?
All MC34978EKR2 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 MC34978EKR2 meets industry standards.
7.What is the process for return or replacement of MC34978EKR2?
All MC34978EKR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC34978EKR2, 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 MC34978EKR2 part is unused and in its original packaging.
Return procedure for MC34978EKR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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