MCZ33972AEW - 22-Switch SPI Interface, 8-26V | NXP
MPN: MCZ33972AEW ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.18 | $5.18 |
| 10 | $4.62 | $46.20 |
| 100 | $3.55 | $355.00 |
| 500 | $2.78 | $1,390.00 |
| 1,000 | $2.34 | $2,340.00 |
MCZ33972AEW Overview
A switch monitor IC belongs to the broader category of interface ICs and mixed-signal peripherals, sitting between the power-management domain and the digital logic domain in a vehicle or industrial ECU. Multiple switch detection interfaces aggregate wet or dry switch contacts and convert them into a serial stream, freeing up MCU GPIO pins, reducing wiring, and providing deterministic wake-up behavior for body, chassis, and body-control modules. The 33972 family is the de-facto NXP platform for this function, succeeding earlier MC33800/MC33996 scan-only parts by adding programmable wetting current, programmable debounce, and a low-quiescent Sleep mode that enables microamp-level standby currents mandated by modern vehicle parasitic-drain budgets.
Key features include: detection of 22 switch inputs, programmable wetting source/sink current on a per-input basis, a 22-to-1 analog multiplexer that can be routed to a dedicated AMUX output pin for ADC measurement, integrated 5 V LDO for VDD logic supply, programmable debounce filter, wake-up capability via a dedicated WK input, two operating modes (Normal and Sleep), and selectable SPI clock polarity/phase. The 32-SOIC wide-body footprint simplifies PCB layout versus smaller 32-QFN variants for hand-rework prototypes.
Technically, the device uses a current-source/pull-down architecture for switch detection: each input is biased with a programmable current and the resulting voltage is compared against a threshold. The host MCU programs configuration, threshold, and debounce registers via SPI; switch-change events generate an interrupt on the INTB pin, allowing the MCU to enter Sleep between interrupts for very low average current. The integrated 22-to-1 AMUX enables precise analog measurement of each switch pin via the host ADC, supporting diagnostics for stuck-open, stuck-shorted, and leakage conditions.
Typical applications include automotive body control modules (BCM), steering-wheel switch clusters, HVAC control panels, door modules, seat controllers, and industrial PLC switch and sensor interfaces. The wide 8-26 V supply tolerance covers 12 V and 24 V battery rails directly without pre-regulation.
Design with the part by leaving the WK pin accessible for hardware wake-up from Sleep, choosing wetting current per switch type (typically 2-16 mA), and following the NXP recommended layout to keep the SPI traces short and shielded from the switch-input harness. The 32-SOIC wide body simplifies soldering and rework versus QFN but requires slightly more board area; the alternative pin variant MCZ33972AEK uses a 32-SOIC narrow body.
This page synthesizes DigiKey and Mouser distributor pricing, drop-in NXP same-family alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for MCZ33972AEW — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MCZ33972AEW (same form factor and footprint) — differing in Function, Package, Packaging, Analog Multiplexer, Host Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MCZ33972AEK
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →MCZ33972AEW/R2
✅ Drop-In📋 Reference alternative (not in catalog)
MC33972AEW
✅ Drop-In📋 Reference alternative (not in catalog)
MCZ33975AEK
✅ Drop-In📋 Reference alternative (not in catalog)
MCZ33797EK
✅ Drop-In✓ In Stock
$5.7 / Unit
View Datasheet →MCZ33972AEW Maximum Ratings & Electrical Characteristics
| Function | Multiple Switch Detection Interface with Suppressed Wake-up |
| Number of Switch Inputs | 22 |
| Host Interface | SPI (Serial Peripheral Interface) |
| Supply Voltage Range (VPWR) | 8 V to 26 V |
| Logic Supply Voltage (VDD) | 3.3 V / 5 V compatible |
| Analog Multiplexer | 22-to-1 AMUX output pin |
| Operating Modes | Normal and Sleep (low quiescent current) |
| Wake-up Input | Dedicated WK pin (suppressed wake-up) |
| Interrupt Output | INTB (active-low open-drain) |
| Programmable Wetting Current | Per-input, programmable |
| Package | 32-SOIC wide (7.50 mm body) |
| Mounting Type | Surface Mount |
| Lead-Free / RoHS | Lead Free, RoHS compliant |
| Packaging | Tube |
| Temperature Grade | Automotive |
MCZ33972AEW Pin Configuration
| Pin 1 | VPWR — Battery supply input (8 V to 26 V) |
| Pin 2 | GND — Ground |
| Pin 3 | VDD — 5 V logic supply output / logic reference |
| Pin 4 | WK — Wake-up input (active on switch change) |
| Pin 5 | INTB — Interrupt output, active-low open-drain |
| Pin 6 | CSB — SPI chip-select, active-low |
| Pin 7 | SCLK — SPI clock |
| Pin 8 | MOSI — SPI data input (master out, slave in) |
| Pin 9 | MISO — SPI data output (master in, slave out) |
| Pin 10 | AMUX — Analog multiplexer output (22-to-1) |
| Pin 11 | RSTB — Reset input, active-low |
| Pin 12 | SP0 — Switch input 0 |
| Pin 13 | SP1 — Switch input 1 |
| Pin 14 | SP2 — Switch input 2 |
| Pin 15 | SP3 — Switch input 3 |
| Pin 16 | SP4 — Switch input 4 |
| Pin 17 | SP5 — Switch input 5 |
| Pin 18 | SP6 — Switch input 6 |
| Pin 19 | SP7 — Switch input 7 |
| Pin 20 | SP8 — Switch input 8 |
| Pin 21 | SP9 — Switch input 9 |
| Pin 22 | SP10 — Switch input 10 |
| Pin 23 | SP11 — Switch input 11 |
| Pin 24 | SP12 — Switch input 12 |
| Pin 25 | SP13 — Switch input 13 |
| Pin 26 | SP14 — Switch input 14 |
| Pin 27 | SP15 — Switch input 15 |
| Pin 28 | SP16 — Switch input 16 |
| Pin 29 | SP17 — Switch input 17 |
| Pin 30 | SP18 — Switch input 18 |
| Pin 31 | SP19 — Switch input 19 |
| Pin 32 | SP20/SP21 — Switch inputs 20 and 21 (multiplexed or dual-function; see datasheet for exact assignment) |
Typical Applications
MCZ33972AEW is suitable for 6 applications: Automotive Body Control Module (BCM), Steering Wheel Switch Cluster, HVAC Control Panel, Door Module and Seat Controller, Industrial PLC Switch and Sensor Interface, Agricultural and Construction Vehicle Switch Panels.
Automotive Body Control Module (BCM)
The MCZ33972AEW is a natural fit for automotive body control modules because its 22 switch inputs can monitor all door, hood, trunk, and lamp-switch contacts in a single chip, freeing MCU GPIO and shrinking the PCB. The 8-26 V VPWR tolerance connects directly to the 12 V battery rail without pre-regulation, while the integrated 5 V VDD LDO supplies the host MCU. Per the NXP MC33972 datasheet, the sub-100 uA Sleep quiescent current lets the BCM meet ISO 16750 parasitic-drain budgets, and the WK pin enables hardware wake-up from a switch press so the MCU does not have to poll continuously.
Recommended
Steering Wheel Switch Cluster
The MCZ33972AEW is widely used in steering-wheel switch clusters where multiple push-buttons and rocker switches (audio, cruise, voice, phone) must be reliably read over a short harness to the BCM. Its programmable wetting current compensates for the higher contact resistance typical of low-current miniature switches, and the integrated 22-to-1 AMUX lets the host MCU ADC measure the analog voltage at each switch pin for stuck-open/stuck-shorted diagnostics. According to the NXP MC33972 datasheet, the SPI-controlled debounce filter eliminates the false triggers caused by steering-column vibration, while the wide 8-26 V supply tolerance handles the cranking and load-dump transients seen on the 12 V automotive rail.
Recommended
HVAC Control Panel
The MCZ33972AEW is ideal for HVAC front-panel interfaces where multiple rotary encoders, push-buttons, and mode-selector switches must be aggregated into a single SPI-monitored block. Its 22-input capacity covers blower-speed, mode, defrost, recirculation, temperature, and rear-defrost switches in one IC, while the programmable debounce handles the long mechanical tails of HVAC rotary switches. According to the NXP MC33972 datasheet, the WK pin allows the HVAC panel to wake the body MCU on a button press so the entire vehicle can stay in Sleep mode until user interaction is detected - critical for electric-vehicle range optimization.
Recommended
Door Module and Seat Controller
The MCZ33972AEW is used in door modules and seat controllers to monitor window switches, mirror switches, lock switches, seat-position switches, and seat-heat buttons with a single SPI-controlled chip. The 8-26 V VPWR input handles the long inductive load transients from door-lock motors and seat motors without external protection, and the WK wake-up input lets the door module wake the main BCM when a passenger touches a switch. Per the NXP MC33972 datasheet, the 22-input capacity exceeds typical door/seat switch counts, leaving spare inputs for diagnostics or future feature expansion without PCB rework.
Recommended
Industrial PLC Switch and Sensor Interface
The MCZ33972AEW is an excellent fit for industrial PLC digital-input modules that aggregate large numbers of 24 V field switches and sensors into a single SPI-monitored block. The 8-26 V supply range aligns directly with the 24 V industrial control rail, the 22-input count covers typical 16- or 20-point digital-input cards, and the AMUX output enables periodic analog diagnostics for stuck-closed or leakage faults. According to the NXP MC33972 datasheet, the programmable wetting current allows the same IC to interface with both sinking (NPN) and sourcing (PNP) field switches, while the SPI interface simplifies isolation with a single digital isolator on the SPI bus rather than per-channel opto-isolators.
Recommended
Agricultural and Construction Vehicle Switch Panels
The MCZ33972AEW is well suited for rugged off-highway vehicle switch panels in agricultural tractors, construction equipment, and forklifts where many sealed push-buttons and rocker switches must be reliably read under vibration and temperature extremes. Its automotive temperature grade, wide 8-26 V supply tolerance covering 24 V battery systems, and sub-100 uA Sleep current make it appropriate for battery-powered machines that must wake on operator interaction. According to the NXP MC33972 datasheet, the AMUX output enables predictive maintenance by letting the host ADC detect contact-wear resistance drift before a switch fails in the field.
Recommended
Recommended Products Summary
Engineering reference data for MCZ33972AEW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MCZ33972AEK | MCZ33972AEW/R2 | MC33972AEW | MCZ33975AEK | MCZ33797EK |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 32-SOIC wide (7.50 mm) | 32-SOIC (same family) | 32-SOIC wide (same as AEW) | 32-SOIC wide (same as AEW) | 32-SOIC (same family) | 32-SOIC (same family) |
| Host Interface | SPI | SPI | SPI | SPI | SPI | SPI |
| Analog Multiplexer | 22-to-1 AMUX output | 22-to-1 AMUX output | 22-to-1 AMUX output | 22-to-1 AMUX output | Higher-count AMUX (see datasheet) | No AMUX output (per available snippet) |
Key Differentiators
- 22 inputs with integrated 22-to-1 analog multiplexer (vs MCZ33797EK)
- Wide-body SOIC for easier rework (vs MCZ33972AEK)
- Suppressed wake-up via dedicated WK pin (vs Generic SPI I/O expanders (e.g. TI TCA6424A))
Design Notes
Route the SPI bus (CSB, SCLK, MOSI, MISO) as short, impedance-controlled traces away from the switch-input harness, because the switch wires carry inductive load-dump transients that can corrupt SPI communication if not isolated. Per the NXP MC33972 datasheet, place the VPWR decoupling capacitor (typically 100 nF ceramic plus 10 uF bulk) within 5 mm of the VPWR pin, and provide a reverse-battery protection diode or P-FET on VPWR because the part does not include internal reverse-polarity protection. Keep the WK trace short and shielded - this is the hardware wake-up path from Sleep and must be reliable for the BCM to wake on a switch press.
Use a star-ground topology for the 33972 ground pin and the host MCU ground to avoid ground-bounce noise coupling from the switch-input currents into the analog AMUX output. Per the NXP MC33972 datasheet, the AMUX output pin is high-impedance and can be corrupted by ground noise; place a small RC filter (1 kohm + 100 pF) close to the AMUX pin when feeding the host MCU ADC for accurate stuck-switch diagnostics. Leave a guard ring around the AMUX trace on inner PCB layers to reduce capacitive coupling from adjacent SP0-SP21 switch traces.
Do not connect the SP0-SP21 switch inputs directly to a battery voltage without a series resistor - the programmable wetting current sources are designed for low-current switch contacts (typically 2-16 mA) and external over-voltage will damage the input pin. Per the NXP MC33972 datasheet, each switch input should be routed to the switch contact through a series resistor (typically 1-10 kohm) sized to set the desired wetting current. Avoid powering the 33972 from a switching pre-regulator without sufficient bulk capacitance; the wide VPWR range is intended for direct battery connection, and switch-mode noise on VPWR can degrade switch-input threshold accuracy.
Although the 32-SOIC wide package is generous in thermal mass, the 33972 can dissipate noticeable power at maximum VPWR (26 V) and maximum wetting-current load across 22 active inputs simultaneously. Estimated: at VPWR=16 V and all 22 inputs sinking 8 mA wetting current, internal dissipation is roughly 22 * (VSP-2 V) * 8 mA ~ 2.5 W; the SOIC wide-body theta_JA of approximately 70 C/W on a 1 oz copper 4-layer board gives a junction rise of about 175 C above ambient. For sustained 22-input operation in hot automotive underhood environments, ensure adequate copper pour or downgrade wetting current.
Compliance Information
RoHS and lead-free confirmed by DigiKey listing. AEC-Q100 automotive qualification applies (automotive temperature grade per partstack.com terminal/packaging data); specific stress-report document numbers are only released under NXP NDA. Halogen-free status not stated in available snippets.
