My Inquiry
My Account
NXP Semiconductors MC34978AESR2
- Part No.:
- MC34978AESR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
MC34978AESR2.pdf
- Description:
- IC INTERFACE SPECIALIZED 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,539
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
MC34978AESR2 from NXP Semiconductors is a 22-channel switch detection interface IC designed for automotive and industrial control panels. It detects open/closed states of up to 14 switch-to-ground (SG) and 8 programmable switch (SP) inputs, supports programmable wetting current (2–20 mA), and integrates a 24:1 analog multiplexer with battery voltage sensing (via SG5/÷6) and die temperature monitoring - all delivered through SPI to an MCU. It operates across 4.5 V to 36 V battery supply and features Low-power Mode with 30 µA VBATP quiescent current.
For engineers reviewing the MC34978AESR2 datasheet, MC34978AESR2 pinout, MC34978AESR2 application, or MC34978AESR2 equivalent, this page delivers verified functional identity, confirmed QFN-32 package mapping, validated SPI timing (8 MHz max), exact wetting current modes (7 selectable levels), and real-world design meaning for LPM wake-up, AMUX hardwire selection, and ±14 V switch input tolerance - critical for body control module and HVAC panel designs.
Technical Context
The MC34978AESR2 implements dual-mode switch detection: Normal mode enables full configuration and wetting current sourcing (pulse or continuous), while Low-power Mode uses a 192 kHz internal oscillator to periodically poll inputs with <30 µA VBATP supply current. Its 24:1 analog multiplexer routes SG/SP channel signals to AMUX, with dedicated divider-by-6 on SG5 for battery sensing and integrated temperature sensor output - both accessible without SPI overhead.
Switch inputs are protected against -14 V to +38 V transients per AEC-Q100 ESD specs (±8 kV contact discharge on VBATP/WAKE_B), and detection thresholds adapt dynamically: 4.0 V nominal in Normal mode, reduced to 0.55×VBATP below 6.0 V, and 100–300 mV in LPM for SG pins only. Wake-up is supported via INT_B edge or external WAKE_B assertion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channels | 22 total: 14 SG (switch-to-ground) + 8 SP (programmable SB/SG) |
| Wetting Current | Selectable 2, 6, 8, 10, 12, 14, 16, or 20 mA - enables reliable contact cleaning in harsh environments |
| LPM Supply Current | IBATP = 30 µA - ensures <100 µA system sleep current in body control modules |
| AMUX Functionality | 24:1 analog mux with buffered AMUX output; includes SG5÷6 battery sense and die temp sensor |
| Supply Range | VBATP = 4.5 V to 36 V; VDDQ = 3.0 V to 5.25 V - supports 12 V/24 V automotive systems with reverse-battery protection |
| SPI Interface | 3.3 V / 5.0 V compatible; 8 MHz max clock; interrupt-driven reporting via open-drain INT_B |
| Operating Temp | -40 °C to +105 °C - qualified for passenger compartment and under-hood auxiliary control |
Pinout & Package
MC34978AESR2 is housed in a 32-pin QFN (WF-Type) package with exposed thermal pad, rated for -40 °C to +105 °C operation and optimized for compact automotive PCB layouts.
| 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 and LPM polling |
| SG0–SG13 | Switch-to-Ground Inputs | Dedicated low-side switch detection; enable 100–300 mV LPM threshold and glitch filtering |
| VBATP | Battery Supply Input | Primary power rail (4.5–36 V); requires external reverse-battery diode per datasheet Figure 24 |
| VDDQ | Logic Supply | 3.3 V / 5.0 V digital I/O reference; sets MISO drive level and SPI buffer thresholds |
| AMUX | Analog Multiplexer Output | Buffered analog output for battery voltage (SG5÷6), die temperature, or any SG/SP channel |
| INT_B | Interrupt Output | Open-drain signal indicating switch state change; also accepts falling-edge wake-up in LPM |
| WAKE_B | Wake-up Control | Open-drain output to enable external power rails; doubles as input for external wake events |
| CS_B, SCLK, MOSI, MISO | SPI Interface | Standard 4-wire SPI; supports daisy-chaining and register read/write for configuration and status |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Wetting Operation | Pulse (20 ms) or continuous wetting current - prevents contact oxidation in infrequent-use switches |
| Hardwire AMUX Selection | Two- or three-pin hardware select - eliminates SPI dependency for critical battery/temp reads at boot |
| Integrated Battery Sensing | SG5 input with fixed ÷6 divider - provides direct 2–4.67 V scaled battery voltage for MCU ADC |
| Thermal Monitoring | On-die temperature sensor output via AMUX - enables overtemperature shutdown coordination with MCU |
| LPM Glitch Filtering | 1.2 ms debounce time - suppresses mechanical switch bounce without MCU firmware overhead |
Applications
| Automotive Body Control Module | Industrial HMI Panel |
|---|---|
Use Scenario: Monitoring door lock/unlock, trunk release, and mirror adjustment switches in vehicle body domain controller. IC Role / Device Role / Timing Role: Centralized switch interface replacing discrete comparators and GPIO expanders; reports state changes via SPI interrupt within 18.5 µs. Use Value: Reduces BOM count by consolidating 22 inputs into one IC with built-in wetting current, eliminating external pull resistors and debounce circuitry. | Use Scenario: Detecting pushbutton and rotary encoder inputs in factory automation operator panels exposed to dust and vibration. IC Role / Device Role / Timing Role: Robust front-end switch conditioner with ±14 V input tolerance and 100–300 mV LPM detection threshold for low-energy wake-up. Use Value: Enables >10-year battery-backed operation in wireless HMI nodes via 30 µA LPM current and configurable polling intervals. |
| Commercial Vehicle HVAC Control | Off-Highway Equipment Dashboard |
Use Scenario: Reading climate mode, fan speed, and recirculation switches in heavy-duty truck HVAC units operating across -40 °C to +85 °C. IC Role / Device Role / Timing Role: High-voltage tolerant switch detector with VBATP UV/OV protection and thermal shutdown at 155 °C. Use Value: Eliminates need for external TVS and overvoltage clamps due to integrated 38 V absolute max switch input rating and ±8 kV contact ESD. | Use Scenario: Managing implement control levers and safety interlock switches in agricultural and construction machinery dashboards. IC Role / Device Role / Timing Role: Fault-tolerant switch monitor with redundant wake-up paths (INT_B edge + WAKE_B input) and SPI error detection. Use Value: Ensures deterministic response to safety-critical inputs even during brownout conditions (4.5 V VBATP minimum). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switch detection applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33978AES | Same QFN-32 package but rated for -40 °C to +125 °C; higher thermal shutdown threshold (185 °C vs 155 °C) | Required for under-hood applications exceeding +105 °C ambient | Select MC33978AES when junction temperature may exceed 105 °C; otherwise MC34978AESR2 suffices for cabin-mounted modules |
| MC34978AEK | SOICW-EP 32-pin package; identical electrical specs and pinout; different thermal resistance (RΘJA = 79 °C/W vs 94 °C/W) | Better suited for legacy SOIC footprints and manual assembly; lower board-level thermal impedance | Choose MC34978AEK for rework-friendly through-hole-compatible layout or where board copper area is limited |
Compared with MC33978AES and MC34978AEK, MC34978AESR2 offers optimal cost/performance balance for cabin-integrated controls: its QFN package enables smaller PCB area than SOICW, while its +105 °C rating covers HVAC, seat, and steering wheel modules without over-spec'ing thermal margin.
Availability
MC34978AESR2 is available at Aetrix Electronics and suitable for automotive body control modules, industrial HMI panels, commercial vehicle HVAC systems, and off-highway equipment dashboards requiring stable component supply across extended temperature and voltage ranges.
Supply support for MC34978AESR2 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 MC34978AESR2 belongs to NXP's automotive-grade switch interface product line, engineered specifically for robust, low-power detection of mechanical switches in harsh environments - emphasizing ESD resilience, wide supply range, and integrated diagnostics.
FAQ
What is the maximum switch input voltage range supported by the MC34978AESR2?
The MC34978AESR2 supports a switch input voltage range of -14 V to +38 V per AEC-Q100 stress testing, with guaranteed -18 V minimum design margin. This allows direct connection to automotive battery rails and tolerance of load-dump transients without external clamping diodes - a key requirement for body control and dashboard switch interfaces where wiring harnesses expose inputs to high-energy noise.
How does the MC34978AESR2 handle low-battery conditions below 6.0 V VBATP?
Below 6.0 V, the MC34978AESR2 remains functional down to 4.5 V VBATP but with degraded parametric performance: switch detection threshold scales to 0.55×VBATP, wetting current accuracy drops (e.g., 6 mA mode becomes 2.0–6.6 mA), and some specifications are no longer guaranteed. The device maintains SPI communication and LPM wake-up capability, enabling graceful degradation in deep-discharge scenarios common in parked vehicle monitoring.
Can the MC34978AESR2 measure battery voltage directly?
Yes - the MC34978AESR2 integrates a dedicated ÷6 resistor divider on SG5 input, allowing direct battery voltage measurement via the AMUX output. When SG5 is configured for battery sensing, the AMUX pin delivers a scaled 2–4.67 V signal corresponding to 12–28 V battery range, with ±5.0% accuracy over temperature. This eliminates external scaling components and enables MCU ADC-based battery health monitoring without SPI polling overhead.
What is the purpose of the WAKE_B pin on the MC34978AESR2?
The WAKE_B pin on the MC34978AESR2 serves dual roles: as an open-drain output it drives external power-enable circuits to wake up downstream subsystems (e.g., MCU or display), and as an input it accepts falling-edge signals to wake the MC34978AESR2 itself from Low-power Mode. This bidirectional capability enables hierarchical power management - for example, a door handle sensor can assert WAKE_B to activate the MC34978AESR2, which then asserts its own WAKE_B to power the main controller.
Does the MC34978AESR2 support hardware-only analog multiplexer selection?
Yes - the MC34978AESR2 supports two- or three-pin hardwire AMUX selection, allowing analog channels (battery voltage, temperature, or any SG/SP input) to be routed to the AMUX pin without SPI communication. This feature ensures deterministic analog reads during boot-up or fault recovery when the MCU SPI interface is inactive, critical for fail-safe battery monitoring and thermal protection in automotive safety-related systems.
MC34978AESR2 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:
- -
- Voltage - Supply:
- 4.5V ~ 36V
- Supplier Device Package:
- 32-QFN-EP (5x5)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
MC34978AESR2 FAQ
1.How can I place an order for MC34978AESR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34978AESR2 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 MC34978AESR2 reliable?
The price and inventory of MC34978AESR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978AESR2 is usually 5 days.
3.What payment methods are accepted for MC34978AESR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978AESR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34978AESR2?
MC34978AESR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34978AESR2 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 MC34978AESR2?
For technical support, including MC34978AESR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978AESR2 requirements.
6.How does Aetrix verify that MC34978AESR2 is sourced from the original manufacturer or authorized distributors?
All MC34978AESR2 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 MC34978AESR2 meets industry standards.
7.What is the process for return or replacement of MC34978AESR2?
All MC34978AESR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC34978AESR2, 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 MC34978AESR2 part is unused and in its original packaging.
Return procedure for MC34978AESR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MC34978AESR2 Tags
-
NVT4857UKAZ
NXP Semiconductors
-
TCA8418RTWR
Texas Instruments
-
PCA9546APWR
Texas Instruments
-
MD0100N8-G
Microchip Technology
-
PCA9548APW,118
NXP Semiconductors
-
PCA9540BDP,118
NXP Semiconductors
-
PCA9548APWR
Texas Instruments
-
PCA9546APW,118
NXP Semiconductors
-
PTN3360DBS,518
NXP Semiconductors
-
PCA9546ABS,118
NXP Semiconductors
-
PCA9518PWR
Texas Instruments
-
PCA9545APW,118
NXP Semiconductors
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
