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Home > Products > Integrated Circuits (ICs) > Interface > Specialized

NXP Semiconductors MC34978ES

Name: MC34978ES
Brand: NXP Semiconductors
SKU: MC34978ES
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MC34978ES

Manufacturer:: NXP Semiconductors

Category:: Specialized

Package:: 32-VFQFN Exposed Pad

Datasheet:: MC34978ES.pdf

Description:: IC INTERFACE SPECIALIZED 32QFN

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MC34978ES 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 = 30 µA typ.), and interfaces directly with 3.3 V/5.0 V MCUs for vehicle HVAC, lighting, and gateway I/O control.

For engineers reviewing the MC34978ES datasheet, MC34978ES pinout, MC34978ES application, or MC34978ES equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated QFN-32 package mapping, confirmed SPI-driven switch-state reporting, and two rigorously cross-checked alternative parts for automotive I/O consolidation designs.

Technical Context

The MC34978ES integrates dual-mode operation: Normal mode enables full configuration via SPI while actively sourcing programmable wetting currents (2–20 mA) to 22 switch inputs; Low-power mode reduces IBATP to 30 µA while maintaining wake-on-change capability via INT_B and WAKE_B pins. Its internal 24:1 AMUX routes selected SG/SP channel voltage-plus battery (via SG5 divider) and die temperature-to the buffered AMUX output pin.

Switch detection uses voltage-threshold comparators with hysteresis (VICTHR = 4.0 V ±0.3 V), configurable per-channel wetting current, and glitch filtering (5–18 µs). The device includes on-chip bandgap reference, oscillator (4 MHz normal / 192 kHz LPM), thermal shutdown (155 °C), and AEC-Q100 qualified ESD protection (±8 kV contact on VBATP/WAKE_B).

Key Specifications

Parameter	Value and Actual Design Meaning
Battery Input Range	4.5 V to 36 V - supports cold-crank (4.5 V) and load-dump (36 V) transients in automotive systems without external regulators.
Switch Inputs	22 total: 8 programmable (SP0–SP7), 14 switch-to-ground (SG0–SG13) - enables mixed topology (pull-up/pull-down) I/O consolidation.
Wetting Current	2, 6, 8, 10, 12, 14, 16, or 20 mA - programmable per-channel to ensure reliable contact closure detection across varying switch resistance and contamination.
LPM Supply Current	30 µA typ. at VBATP = 6–28 V - meets automotive sleep-current budgets for always-on gateway and body-control modules.
SPI Interface	3.3 V / 5.0 V compatible, up to 8 MHz - allows direct connection to common MCU SPI peripherals without level-shifting.
AMUX Output	Buffered analog output (VOHAMUX ≥ VDDQ – 0.1 V, VOLAMUX ≤ 50 mV) - drives MCU ADC input with minimal loading error and offset ≤ ±15 mV (QFN).
Operating Temp	-40 °C to +105 °C - qualified for under-hood and cabin-mounted automotive applications per AEC-Q100 Grade 2.

Pinout & Package

MC34978ES is housed in a 32-pin QFN (WF-Type) package with exposed pad (EP), optimized for thermal performance and space-constrained automotive PCBs. Pin pitch is 0.5 mm; package footprint matches JEDEC MO-220 standard.

Pin/Terminal	Circuit Role	Design Meaning
GND (Pin 1)	Ground reference	Primary logic/analog ground; EP must be soldered to system GND for thermal and EMI integrity.
MOSI (Pin 2)	SPI data input	Receives register writes from MCU; accepts 3.3 V/5.0 V logic levels with 300 mV hysteresis.
SCLK (Pin 3)	SPI clock input	Drives internal state machine; max 8 MHz; timing tolerances defined per Figure 7.
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 pull-up or pull-down; support wetting current programming and LPM polling.
SG0–SG13 (Pins 5–11, 14–20)	Switch-to-ground inputs	Dedicated low-side sensing; each has independent wetting current selection and VICTHR = 100–300 mV in LPM.
VBATP (Pin 12)	Battery supply input	Accepts 4.5–36 V; includes POR (2.7–3.8 V), UVLO (4.3 V), OVLO (32–37 V), and reverse-battery protection requirement.
WAKE_B (Pin 13)	Open-drain wake output/input	Drives external power-enable circuits; also accepts falling-edge wake events during LPM.
INT_B (Pin 25)	Open-drain interrupt output	Asserts on switch state change; active-low pulse (90–110 µs); requires external pull-up to VDDQ.
AMUX (Pin 26)	Analog multiplexer output	Provides buffered voltage from selected SG/SP, battery (SG5/6), or temperature sensor; used for MCU ADC sampling.
VDDQ (Pin 27)	I/O supply	3.0–5.25 V; sets SPI logic levels and MISO driver strength; UVLO threshold = 2.2–2.8 V.
MISO (Pin 28)	SPI data output	Tri-statable; outputs switch status, AMUX data, and register reads; VOL ≤ 0.4 V @ 1 mA.
EP	Exposed thermal pad	Must be connected to GND plane; contributes to RΘJC = 2.0 °C/W and improves thermal reliability.

Key Features

Feature	Design Value
24:1 Analog Multiplexer	Routes any of 22 switch inputs, battery voltage (divided by 6), or temperature sensor to AMUX pin-enabling single-ADC monitoring of all critical analog signals.
Independent Wetting Current Programming	Eight selectable levels (2–20 mA) per SG/SP channel ensure reliable detection of high-resistance switches (e.g., corroded HVAC actuators) without overdriving low-R contacts.
Low-Power Mode with Wake-on-Change	30 µA quiescent current + hardware-interrupt wake (INT_B) and external-event wake (WAKE_B) eliminate MCU polling, extending battery life in always-on systems.
Integrated Battery & Temperature Monitoring	VBATP sensed via SG5 (6× divider, ±5% accuracy) and on-die temperature sensor (8 mV/°C) reduce BOM count and improve system diagnostics without external components.
AEC-Q100 Qualified Robustness	±8 kV contact ESD on VBATP/WAKE_B, -14 V to 38 V switch input range, and thermal shutdown (155 °C) ensure operation in harsh automotive environments.

Applications

Automotive HVAC Control	Vehicle Lighting Switch Interface
Use Scenario: Monitoring 18 rotary/dip-switch positions and 4 push-button controls in a climate control module. IC Role / Device Role / Timing Role: MC34978ES scans all 22 inputs via SPI, applies 8 mA wetting current to rotary contacts, and reports state changes to MCU within 18.5 µs interrupt delay. Use Value: Eliminates 22 discrete pull-up resistors and GPIOs; reduces PCB area by >40% vs discrete solution while supporting cold-crank operation down to 4.5 V.	Use Scenario: Reading headlight, fog light, and interior lamp toggle switches in a central body controller. IC Role / Device Role / Timing Role: MC34978ES configures SP0–SP3 as pull-up and SG0–SG9 as pull-down, enabling mixed-logic switch topologies with shared AMUX-based battery monitoring. Use Value: Single IC replaces multiple switch interface ICs; built-in 6× battery divider provides real-time voltage health check without extra op-amps or dividers.
Industrial PLC Input Module	In-Vehicle Networking Gateway
Use Scenario: Consolidating 22 dry-contact inputs (e.g., limit switches, safety interlocks) in a DIN-rail mounted PLC I/O card. IC Role / Device Role / Timing Role: MC34978ES operates in Normal mode with 12 mA wetting current, detects open/closed states, and transfers status via SPI to ARM Cortex-M7 host processor. Use Value: Meets IEC 61000-4-5 surge immunity requirements via robust 36 V VBATP rating and integrated glitch filtering (5–18 µs).	Use Scenario: Managing physical-layer switch inputs (mode select, reset, diagnostic buttons) in an automotive Ethernet gateway ECU. IC Role / Device Role / Timing Role: MC34978ES runs in LPM (30 µA) between button presses, wakes instantly on WAKE_B edge, and reports state via SPI before Ethernet stack initialization completes. Use Value: Enables <100 µA total system sleep current; AMUX output feeds gateway's internal ADC for battery voltage trending and thermal derating decisions.

Automotive HVAC Control

Vehicle Lighting Switch Interface

Use Scenario: Monitoring 18 rotary/dip-switch positions and 4 push-button controls in a climate control module.

IC Role / Device Role / Timing Role: MC34978ES scans all 22 inputs via SPI, applies 8 mA wetting current to rotary contacts, and reports state changes to MCU within 18.5 µs interrupt delay.

Use Value: Eliminates 22 discrete pull-up resistors and GPIOs; reduces PCB area by >40% vs discrete solution while supporting cold-crank operation down to 4.5 V.

Use Scenario: Reading headlight, fog light, and interior lamp toggle switches in a central body controller.

IC Role / Device Role / Timing Role: MC34978ES configures SP0–SP3 as pull-up and SG0–SG9 as pull-down, enabling mixed-logic switch topologies with shared AMUX-based battery monitoring.

Use Value: Single IC replaces multiple switch interface ICs; built-in 6× battery divider provides real-time voltage health check without extra op-amps or dividers.

Industrial PLC Input Module

In-Vehicle Networking Gateway

Use Scenario: Consolidating 22 dry-contact inputs (e.g., limit switches, safety interlocks) in a DIN-rail mounted PLC I/O card.

IC Role / Device Role / Timing Role: MC34978ES operates in Normal mode with 12 mA wetting current, detects open/closed states, and transfers status via SPI to ARM Cortex-M7 host processor.

Use Value: Meets IEC 61000-4-5 surge immunity requirements via robust 36 V VBATP rating and integrated glitch filtering (5–18 µs).

Use Scenario: Managing physical-layer switch inputs (mode select, reset, diagnostic buttons) in an automotive Ethernet gateway ECU.

IC Role / Device Role / Timing Role: MC34978ES runs in LPM (30 µA) between button presses, wakes instantly on WAKE_B edge, and reports state via SPI before Ethernet stack initialization completes.

Use Value: Enables <100 µA total system sleep current; AMUX output feeds gateway's internal ADC for battery voltage trending and thermal derating decisions.

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 and pinout; rated for -40 °C to +125 °C (vs. MC34978ES's +105 °C); higher temp grade enables under-hood placement.	Required where junction temperature exceeds 105 °C (e.g., engine bay sensors); identical electrical specs and firmware compatibility.	Select MC33978AES when ambient operating temperature reaches 125 °C; no PCB or firmware changes needed.
MC34978EK	SOICW-EP 32-pin package (vs. QFN); same -40 °C to +105 °C rating; identical electrical characteristics and register map.	Favored for manual assembly, prototyping, or legacy SOIC footprints; larger thermal mass but lower thermal conductivity than QFN.	Choose MC34978EK for hand-soldered prototypes or designs requiring SOIC mechanical robustness; same schematic symbol and SPI code.

Compared with MC34978ES, MC33978AES extends junction temperature range to 125 °C for under-hood use, while MC34978EK offers SOIC packaging for easier rework and thermal stability in non-space-constrained layouts-both retain identical functionality, register compatibility, and wetting current programming.

Availability

MC34978ES is available at Aetrix Electronics and suitable for automotive HVAC control, industrial PLC input modules, and in-vehicle networking gateways requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle support.

Supply support for MC34978ES 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 MC34978ES belongs to NXP's SMARTMOS switch interface product line, engineered specifically for high-reliability automotive body electronics and industrial control systems requiring consolidated I/O, low sleep current, and integrated diagnostics.

FAQ

What is the maximum switch input voltage range supported by the MC34978ES?

The MC34978ES supports a switch input voltage range of -1.0 V to 36 V relative to GND. This accommodates reverse-battery transients, load-dump spikes, and negative glitches common in automotive 12 V/24 V systems. The absolute maximum rating extends to -14 V to 38 V per Table 3, ensuring robustness against short-duration overvoltage events without latch-up or damage.

How does the MC34978ES handle battery voltage monitoring?

The MC34978ES monitors battery voltage using its internal 24:1 analog multiplexer: SG5 input is configured as a dedicated 6× resistor divider (VBATP/6), and the resulting voltage appears on the AMUX pin. Accuracy is ±5.0% over temperature, enabling MCU ADC-based battery health tracking without external components-critical for low-power gateway modules.

Can the MC34978ES operate in low-power mode while maintaining wake-up capability?

Yes, the MC34978ES achieves 30 µA typical VBATP supply current in Low-power mode (LPM) while retaining full wake-up functionality via INT_B (change-of-state interrupt) and WAKE_B (external event input). LPM wake-up latency is ≤1000 µs after CS_B edge or WAKE_B falling edge, making it suitable for always-on automotive modules with strict sleep-current budgets.

What is the purpose of the programmable wetting current in the MC34978ES?

The MC34978ES provides eight selectable wetting current levels (2, 6, 8, 10, 12, 14, 16, or 20 mA) per switch input to overcome contact oxidation, film resistance, and intermittent connections. This ensures reliable detection of mechanical switch closures-even in high-humidity or contaminated environments like automotive HVAC actuators-without requiring external current sources or complex firmware debouncing.

Is the MC34978ES pin-compatible with other devices in the 33978/34978 family?

Yes, the MC34978ES shares identical pinout and register mapping with MC33978AES, MC34978EK, and MC33978EK across both SOICW-EP and QFN packages. Firmware, layout, and schematic symbols are interchangeable-only temperature grade (-40 °C to +105 °C vs. +125 °C) and package type differ, enabling drop-in qualification upgrades or footprint flexibility.

MC34978ES Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: -

Package/Case:: 32-VFQFN Exposed Pad

Packaging:: Tray

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

MC34978ES FAQ

1.How can I place an order for MC34978ES through Aetrix?

Please submit a Request for Quotation (RFQ) for MC34978ES 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 MC34978ES reliable?

The price and inventory of MC34978ES are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34978ES is usually 5 days.

3.What payment methods are accepted for MC34978ES?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34978ES transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MC34978ES?

MC34978ES orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MC34978ES 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 MC34978ES?

For technical support, including MC34978ES datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34978ES requirements.

6.How does Aetrix verify that MC34978ES is sourced from the original manufacturer or authorized distributors?

All MC34978ES 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 MC34978ES meets industry standards.

7.What is the process for return or replacement of MC34978ES?

All MC34978ES units undergo pre-shipment inspection (PSI). If there is an issue with MC34978ES, 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 MC34978ES part is unused and in its original packaging.

Return procedure for MC34978ES:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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