My Inquiry
My Account
NXP Semiconductors MC34978ESR2
- Part No.:
- MC34978ESR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
MC34978ESR2.pdf
- Description:
- IC INTERFACE SPECIALIZED 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,077
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
MC34978ESR2 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 typ. in LPM), and interfaces directly with 3.3 V/5.0 V MCUs for HVAC, lighting, and gateway control applications.
For engineers reviewing the MC34978ESR2 datasheet, MC34978ESR2 pinout, MC34978ESR2 application, or MC34978ESR2 equivalent, key selection criteria include its 32-pin QFN (WF-type) package, -40 °C to +105 °C operating range, independent SG/SP wetting current programming (2–20 mA), AMUX output buffering, and wake-up-on-change capability in low-power mode.
Technical Context
The MC34978ESR2 implements a dual-mode SMARTMOS architecture: Normal mode enables full configuration via SPI and active switch monitoring with programmable pull-up/pull-down currents; Low-power mode reduces quiescent current to 40 µA while retaining wake-up on state change across all 22 inputs. Its internal oscillator provides timing for polling (±15% tolerance at 192 kHz in LPM) and glitch filtering (5–18 µs).
Switch detection uses voltage-threshold comparators with hysteresis (VICTHR = 4.0 V ±0.3 V, VICTHRLPM = 100–300 mV for SG pins), while the AMUX block selects one of 24 inputs (SG0–SG13, SP0–SP7) and buffers the signal to the AMUX pin with <15 mV offset (QFN package, -40 °C to 25 °C). Battery sensing (via SG5, 1:6 divider) and temperature monitoring are routed through the same AMUX path.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Battery Input Range | 4.5 V to 36 V - supports full automotive cold-crank (4.5 V) and load-dump (36 V) conditions without external regulation |
| Switch Inputs | 22 total: 8 programmable (SP0–SP7), 14 switch-to-ground (SG0–SG13) - enables mixed topology wiring in vehicle panels |
| Wetting Current | 2, 6, 8, 10, 12, 14, 16, or 20 mA - selectable per channel group to ensure reliable contact closure detection across varying switch resistances |
| LPM Supply Current | 40 µA typ. (VBATP = 6–28 V) - enables >1-year battery life in always-on automotive modules with periodic wake-up |
| SPI Interface | Up to 8 MHz, 3.3 V/5.0 V compatible - allows direct connection to common MCU SPI peripherals without level-shifting |
| AMUX Output Accuracy | ±5.0% battery sense accuracy (SG5 input), ±3.0% divider ratio error - enables calibrated battery voltage reporting over full operating range |
| Operating Temperature | -40 °C to +105 °C - qualified for under-hood and cabin-mounted automotive ECUs per AEC-Q100 |
Pinout & Package
MC34978ESR2 is housed in a 32-pin QFN (WF-type) package with exposed pad (EP), Pb-free, RoHS-compliant. Thermal resistance RΘJA = 94 °C/W (natural convection), RΘJC = 2.0 °C/W (bottom case), enabling high-power-density placement on compact PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Ground reference | Logic/analog ground; exposed pad (EP) must be connected to system GND for thermal and EMI performance |
| MOSI (Pin 2) | SPI data input | Accepts command/data from MCU; 3.3 V/5.0 V logic compatible, 20 pF max input capacitance |
| SCLK (Pin 3) | SPI clock input | Drives internal state machine; supports up to 8 MHz operation with 56 ns min high/low time |
| CS_B (Pin 4) | SPI chip select | Active-low enable; rising edge triggers LPM wake-up (tCSB_WAKEUP ≤ 1000 µs) |
| SP0–SP7 (Pins 5–8, 21–24) | Programmable switch inputs | Configurable as switch-to-battery or switch-to-ground; support wetting current programming |
| SG0–SG13 (Pins 5–11, 14–20) | Switch-to-ground inputs | Dedicated low-side detection; sustain current = 2.0 mA, wetting current programmable |
| VBATP (Pin 12) | Battery supply input | Primary power rail; requires external reverse-battery protection diode (VF = 0.6–1.0 V) |
| WAKE_B (Pin 13) | Open-drain wake output | Drives external power-enable circuits; internal 125 kΩ pull-up to VDDQ, VOL ≤ 0.4 V @ 1 mA |
| INT_B (Pin 25) | Open-drain interrupt output | Signals switch state change to MCU; active-low pulse (90–110 µs), 125 kΩ internal pull-up |
| AMUX (Pin 26) | Analog multiplexer output | Buffered analog output for battery/temperature/switch readings; VOH ≥ VDDQ – 0.1 V, VOL ≤ 50 mV |
| VDDQ (Pin 27) | I/O supply | Sets SPI logic levels and buffer drive strength; 3.0–5.25 V range, IQ = 10 µA in LPM |
| MISO (Pin 28) | SPI data output | Tri-state digital output; tA ≤ 116 ns access time, 20 pF load, VOL ≤ 0.4 V @ 1 mA |
Key Features
| Feature | Design Value |
|---|---|
| Independent wetting current programming | Eight discrete levels (2–20 mA) per SG/SP group - eliminates need for external current-setting resistors and enables optimized contact cleaning per switch type |
| Integrated battery & temperature monitor | Routed through AMUX pin using SG5 (1:6 divider) and internal sensor - reduces BOM count by removing separate voltage/thermal ICs and associated routing |
| Low-power mode with wake-on-change | 40 µA IBATP, configurable wake sources (any SG/SP, CS_B, INT_B) - extends battery life in always-on systems while maintaining responsiveness |
| Glitch-filtered switch detection | 5–18 µs programmable filter window - rejects mechanical bounce and EMI transients without requiring MCU-side debouncing firmware |
| 24:1 analog multiplexer with buffer | AMUX output drives MCU ADC directly (no external op-amp needed); <15 mV offset ensures accurate voltage measurement across temperature |
| AEC-Q100 qualified | Grade 2 (-40 °C to +105 °C), HBM ESD ≥ ±4 kV (non-VBATP pins) - meets automotive reliability requirements for body electronics and gateways |
Applications
| Automotive HVAC Control Panel | Industrial PLC Input Module |
|---|---|
|
Use Scenario: Detecting button presses, rotary encoder positions, and mode selector switches in climate control units. IC Role / Device Role / Timing Role: Primary switch interface IC; scans 22 inputs via SPI, reports status changes via INT_B, supplies wetting current to prevent oxidation on low-current tactile switches. Use Value: Eliminates discrete resistor networks and debounce logic; enables single-chip solution for 22-switch panel with <100 µs response latency and <40 µA sleep current. |
Use Scenario: Monitoring 22 field device status signals (limit switches, safety interlocks, pushbuttons) in factory automation cabinets. IC Role / Device Role / Timing Role: Centralized digital input conditioner; provides isolated wetting current, ESD-protected inputs (-14 V to 38 V), and buffered analog feedback for diagnostics. Use Value: Reduces I/O module footprint by 30%; supports both dry-contact and powered-sensor inputs without external biasing components. |
| Vehicle Central Gateway Node | Smart Lighting Control System |
|
Use Scenario: Aggregating switch inputs from door modules, seat controls, and steering wheel buttons into a CAN/LIN gateway ECU. IC Role / Device Role / Timing Role: High-integration switch aggregator; routes AMUX output to MCU ADC for battery health monitoring and temperature derating. Use Value: Enables real-time battery voltage tracking alongside switch events using shared AMUX path-no additional ADC channels required. |
Use Scenario: Managing occupancy sensors, dimmer switches, and scene selectors in commercial LED lighting fixtures. IC Role / Device Role / Timing Role: Low-power switch supervisor; enters LPM between user interactions, wakes on any switch press to update lighting state via SPI. Use Value: Achieves <1 µA average system current in standby-critical for battery-powered or energy-harvesting lighting nodes. |
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 QFN-32 package, identical pinout and register map, but rated for -40 °C to +125 °C junction temperature | Required for under-hood applications exceeding +105 °C ambient (e.g., engine bay modules) | Select MC33978AES when ambient temperature exceeds 105 °C; otherwise MC34978ESR2 offers cost-optimized qualification for cabin/body ECUs. |
| MC34978EK | SOICW-EP 32-pin package, same electrical specs and temperature range (-40 °C to +105 °C), but larger footprint and higher RΘJA (79 °C/W) | Suitable for prototyping, legacy board designs, or applications where thermal dissipation is less constrained | Choose MC34978EK for hand-soldering, thermal testing, or compatibility with existing SOIC layouts; MC34978ESR2 preferred for space-constrained production boards. |
Compared with MC33978AES and MC34978EK, the MC34978ESR2 delivers identical switch detection functionality and SPI interface in a thermally optimized QFN package qualified specifically for cabin and body-control applications up to +105 °C-balancing performance, size, and cost without over-specifying temperature grade.
Availability
MC34978ESR2 is available at Aetrix Electronics and suitable for automotive HVAC control, industrial PLC input modules, and vehicle central gateway nodes requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle support.
Supply support for MC34978ESR2 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 analog and mixed-signal ICs.
The MC34978ESR2 belongs to NXP's SMARTMOS switch detection interface product line, designed specifically for robust, low-power monitoring of mechanical switches in harsh automotive and industrial environments.
FAQ
What is the operating temperature range of the MC34978ESR2?
The MC34978ESR2 is specified for operation from -40 °C to +105 °C ambient temperature. This Grade 2 qualification makes it suitable for cabin, body control, and non-under-hood automotive applications. Junction temperature is limited to 150 °C, with thermal shutdown activating at 185 °C for the QFN package. The MC34978ESR2 datasheet defines parametric performance across this full range, including wetting current accuracy and AMUX offset.
How does the MC34978ESR2 support battery voltage monitoring?
The MC34978ESR2 monitors battery voltage via its integrated analog multiplexer (AMUX) using the SG5 input configured as a 1:6 resistive divider. The resulting scaled voltage appears on the AMUX pin and can be read by an MCU ADC. Accuracy is ±5.0% over temperature, with ±3.0% divider ratio error across 6–28 V VBATP. This eliminates the need for external voltage-sense circuitry while sharing the same AMUX path used for temperature and switch analog readings.
Can the MC34978ESR2 detect switch closures in low-power mode?
Yes, the MC34978ESR2 supports full switch state monitoring in Low-power mode (LPM) with typical supply current of 40 µA. It uses an internal 192 kHz oscillator to periodically poll inputs and detect changes, generating an interrupt (INT_B) or wake signal (WAKE_B) upon transition. Glitch filtering (1.0–1.4 ms debounce) and configurable wake sources-including individual SG/SP pins, CS_B, and INT_B-ensure reliable detection without exiting LPM unnecessarily.
What are the key differences between MC34978ESR2 and MC33978AES?
The MC34978ESR2 and MC33978AES share identical functionality, pinout, and QFN-32 package, but differ in temperature qualification: MC34978ESR2 is rated for -40 °C to +105 °C ambient, while MC33978AES extends to +125 °C. Both meet AEC-Q100 Grade 2, but MC33978AES is required for under-hood applications. Electrical specs-including wetting current, AMUX accuracy, and LPM current-are identical across both parts.
Does the MC34978ESR2 require external components for basic operation?
The MC34978ESR2 requires minimal external components: a reverse-battery protection diode on VBATP (VF = 0.6–1.0 V), a 100 nF ceramic bypass capacitor on VDDQ, and a 100 µF aluminum bulk capacitor on VBATP. No external resistors are needed for wetting current or pull-ups-the MC34978ESR2 provides programmable current sources and internal 125 kΩ pull-ups on INT_B and WAKE_B. The exposed pad (EP) must be soldered to GND for thermal and EMI integrity.
MC34978ESR2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 32-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Applications:
- Multiple Switch Detection
- Interface:
- -
- Voltage - Supply:
- 3V ~ 5.25V
- Supplier Device Package:
- 32-QFN-EP (5x5)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
MC34978ESR2 FAQ
1.How can I place an order for MC34978ESR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34978ESR2 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 MC34978ESR2 reliable?
The price and inventory of MC34978ESR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978ESR2 is usually 5 days.
3.What payment methods are accepted for MC34978ESR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978ESR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34978ESR2?
MC34978ESR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34978ESR2 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 MC34978ESR2?
For technical support, including MC34978ESR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978ESR2 requirements.
6.How does Aetrix verify that MC34978ESR2 is sourced from the original manufacturer or authorized distributors?
All MC34978ESR2 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 MC34978ESR2 meets industry standards.
7.What is the process for return or replacement of MC34978ESR2?
All MC34978ESR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC34978ESR2, 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 MC34978ESR2 part is unused and in its original packaging.
Return procedure for MC34978ESR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MC34978ESR2 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…
