MCZ33975EK - 22-Channel Switch Detection SPI Interface | NXP
MPN: MCZ33975EK ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.85 | $6.85 |
| 10 | $6.2 | $62.00 |
| 100 | $5.55 | $555.00 |
| 500 | $4.95 | $2,475.00 |
| 1,000 | $4.4 | $4,400.00 |
MCZ33975EK Overview
A multiple switch detection interface is a specialized analog/digital IC that scans a large array of mechanical or electronic switch contacts and reports their open/closed state to a microcontroller. This category sits within the broader hierarchy of interface ICs -> specialized interfaces -> automotive body electronics drivers. Unlike simple GPIO expanders, switch-detection ICs include programmable wetting current sources, debounce timers, and wake-up suppression logic that allows the rest of the ECU to remain in low-power sleep until a defined switch event occurs.
Key features include detection of up to 22 switch contacts, a 5.5 V to 28 V supply range suited to 12 V automotive rails with load-dump margin, 32 mA programmable wetting current per input to prevent oxidation on mechanical contacts, integrated SPI reporting with interrupt capability, and programmable wake-up behavior. The exposed thermal pad on the 32-SOIC-EP package reduces junction-to-ambient thermal resistance, allowing sustained operation at full wetting-current load across all 22 channels.
The device is built on a high-voltage BCD (Bipolar-CMOS-DMOS) process that supports direct connection to automotive battery nodes without external level shifting. Each of the 22 input channels integrates a wetting-current source, comparator, and debounce state machine. The suppressed wake-up feature allows the IC to ignore brief or noisy switch events and only interrupt the MCU when a genuine, sustained contact transition occurs, dramatically reducing ECU sleep-mode current in body-comfort applications.
Typical applications include automotive body control modules reading door, hood, and trunk ajar switches, climate-control panel buttons, seat-occupancy and buckle switches, lighting controls, and any distributed switch matrix that must communicate over SPI to an MCU. The wide supply range also supports industrial 24 V control panels with similar switch-scanning needs.
When designing with the MCZ33975EK, place 100 nF decoupling capacitors as close as possible to the VBAT and VCC pins, and use the exposed pad as the primary thermal path. Configure the wake-up mask registers to filter mechanical-switch bounce and EMI-induced transients, which are common in automotive wiring harnesses.
This page synthesizes distributor pricing, drop-in same-package alternatives, AEC-Q100 compliance context, and practical EMC design notes that go beyond the manufacturer datasheet to accelerate automotive body-electronics design.
Drop-in alternatives for MCZ33975EK — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC33975EFR2
✅ Drop-In📋 Reference alternative (not in catalog)
MCZ33975EG
✅ Drop-In📋 Reference alternative (not in catalog)
MC33975EKR2
✅ Drop-In📋 Reference alternative (not in catalog)
MCZ33975EK Maximum Ratings & Electrical Characteristics
| Function | Multiple Switch Detection Interface with Suppressed Wake-up |
| Number of Switch Channels | 22 |
| Interface | SPI (Serial Peripheral Interface) |
| Supply Voltage | 5.5 V to 28 V |
| Wetting Current per Channel | 32 mA |
| Wake-up Suppression | Yes (programmable) |
| Package | 32-SOIC-EP (Exposed Pad), 0.295 inch / 7.50 mm width |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +125C (automotive AEC-Q100) |
| AEC-Q100 Qualification | Qualified |
| RoHS Status | Compliant (Lead Free) |
| Packaging | Tube |
| Process Technology | High-voltage BCD (Bipolar-CMOS-DMOS) |
| Input Voltage Rating | Up to 28 V continuous on switch inputs |
| Interrupt Output | Yes (open-drain) |
MCZ33975EK Pin Configuration
| Pin 1 | SG0 — Switch input channel 0 |
| Pin 2 | SG1 — Switch input channel 1 |
| Pin 3 | SG2 — Switch input channel 2 |
| Pin 4 | SG3 — Switch input channel 3 |
| Pin 5 | SG4 — Switch input channel 4 |
| Pin 6 | SG5 — Switch input channel 5 |
| Pin 7 | SG6 — Switch input channel 6 |
| Pin 8 | SG7 — Switch input channel 7 |
| Pin 9 | GND — Ground |
| Pin 10 | SG8 — Switch input channel 8 |
| Pin 11 | SG9 — Switch input channel 9 |
| Pin 12 | SG10 — Switch input channel 10 |
| Pin 13 | SG11 — Switch input channel 11 |
| Pin 14 | SG12 — Switch input channel 12 |
| Pin 15 | SG13 — Switch input channel 13 |
| Pin 16 | SG14 — Switch input channel 14 |
| Pin 17 | SG15 — Switch input channel 15 |
| Pin 18 | SG16 — Switch input channel 16 |
| Pin 19 | SG17 — Switch input channel 17 |
| Pin 20 | SG18 — Switch input channel 18 |
| Pin 21 | SG19 — Switch input channel 19 |
| Pin 22 | SG20 — Switch input channel 20 |
| Pin 23 | SG21 — Switch input channel 21 |
| Pin 24 | INT — Interrupt output (open-drain) |
| Pin 25 | CS — SPI chip select (active low) |
| Pin 26 | SCLK — SPI clock |
| Pin 27 | MOSI — SPI master-out slave-in |
| Pin 28 | MISO — SPI master-in slave-out |
| Pin 29 | VCC — 5 V logic supply |
| Pin 30 | VBAT — Battery supply input (5.5 V-28 V) |
| Pin 31 | NC — Not connected (per datasheet) |
| Pin 32 | NC — Not connected (per datasheet) |
Typical Applications
MCZ33975EK is suitable for 6 applications: Automotive Body Control Module (BCM), Automotive Climate Control Panel, Seat Occupancy and Buckle Switch Detection, Industrial 24 V Control Panel Switch Matrix, Lighting Control Module Switch Reading, Distributed Switch Sub-Node with SPI Aggregation.
Automotive Body Control Module (BCM)
The MCZ33975EK is the primary switch-scanning companion to NXP S32K and MPC56 family MCUs inside a body control module reading door ajar, hood, trunk, and latch switches. Its 22 channels match the typical input count for a mid-range BCM, while the 32 mA wetting current prevents oxidation on frequently-cycled door contacts. The 5.5 V-28 V supply tolerates 12 V load-dump events without external TVS protection on the VBAT pin. Placed adjacent to the MCU with shared SPI bus, the IC reduces wire-harness complexity versus discrete GPIO return paths and keeps ECU sleep current under 100 uA by suppressing nuisance wake-ups from harness noise.
Recommended
Automotive Climate Control Panel
In HVAC control panels, the MCZ33975EK scans up to 22 push-button and rotary-encoder switch inputs and reports state changes over SPI to the panel MCU. The wetting current keeps gold- and silver-alloy contact surfaces free of resistive films, maintaining reliable key-press recognition over a 15-year vehicle service life. The exposed pad on the 32-SOIC-EP package sustains continuous scanning across all 22 channels at elevated cabin temperatures. The suppressed wake-up feature lets the HVAC panel sleep while still waking the body network on a button press, reducing parasitic drain on the vehicle battery.
Recommended
Seat Occupancy and Buckle Switch Detection
The MCZ33975EK reads seat-occupancy mat sensors and buckle-latch switches across all four passenger positions plus a child-presence detection mat, totaling 22 inputs in a full-size SUV. The wetting current is well above the typical 10 mA used in seatbelt buckles, ensuring reliable contact reading even after years of mechanical wear. Its AEC-Q100 Grade 1 qualification (-40C to +125C) handles the wide thermal range of an automotive interior door-pillar mounting location. With SPI interrupt output, the airbag controller can react within one scan cycle to occupancy state changes, enabling faster airbag suppression decisions.
Recommended
Industrial 24 V Control Panel Switch Matrix
In industrial machinery control panels running on 24 V rails, the MCZ33975EK replaces banks of optocouplers and discrete GPIO by scanning up to 22 pushbuttons, selector switches, and key-lock inputs. Its 5.5 V-28 V supply directly accepts the 24 V industrial bus, and the 32 mA wetting current exceeds the IEC 61131-2 contact-wetting recommendation for reliable PLC-style inputs. The SPI interface is compatible with industrial MCUs and embedded PCs that lack sufficient native GPIO. Housed in the 32-SOIC-EP package with exposed pad, the IC delivers sustained wetting-current operation across all 22 channels without thermal shutdown in enclosed control cabinets.
Recommended
Lighting Control Module Switch Reading
Automotive lighting modules use the MCZ33975EK to read headlamp rotary switches, fog-light buttons, and ambient lighting selector inputs and forward them via SPI to the lighting ECU. The 32 mA wetting current prevents the contact-resistance buildup that plagues low-current switch inputs in high-humidity environments. The wide 5.5 V-28 V supply range tolerates cranking dips and load-dump transients on the body wiring harness without losing switch state. With AEC-Q100 qualification and an exposed-pad thermal path, the IC is well-suited to underhood and under-dash mounting locations adjacent to lighting drivers.
Recommended
Distributed Switch Sub-Node with SPI Aggregation
In zonal E/E architectures, the MCZ33975EK sits at door, seat, or roof-rail sub-nodes where 22 switches need to be aggregated and forwarded over SPI to a zonal gateway. Compared with discrete GPIO-plus-resistor designs, the integrated wetting current, debounce, and wake-up logic cut board area by approximately 60 percent and reduce harness pin count. The 32-SOIC-EP exposed pad supports continuous switch scanning across the full AEC-Q100 temperature range. The suppressed-wake-up feature prevents the zonal ECU from waking on harness noise, keeping the sub-node sleep current under 50 uA in modern electric vehicles.
Recommended
Recommended Products Summary
Engineering reference data for MCZ33975EK — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC33975EFR2 | MCZ33975EG | MC33975EKR2 |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 32-SOIC-EP | 32-SOIC-EP - same | 32-SOIC-EP - same | 32-SOIC-EP - same |
| Switch Channels | 22 | 22 | 22 | 22 |
| Supply Voltage | 5.5 V to 28 V | 5.5 V to 28 V | 5.5 V to 28 V | 5.5 V to 28 V |
| Wetting Current | 32 mA | 32 mA | 32 mA | 32 mA |
| Interface | SPI | SPI | SPI | SPI |
| AEC-Q100 | Qualified | Qualified | Qualified | Qualified |
| Shipping Format | Tube (EK suffix) | Tape & Reel (EFR2 suffix) | Tray (EG suffix) | Tape & Reel (EKR2 suffix) |
Key Differentiators
- 22 switch channels in a single IC with integrated 32 mA wetting current (vs Discrete GPIO-plus-resistor designs)
- Programmable suppressed wake-up to filter mechanical bounce and EMI (vs MCZ33972AEW (22-channel LIN switch monitor))
- AEC-Q100 Grade 1 qualified across the full automotive temperature range (vs Industrial-only switch-scanning ICs)
Design Notes
Place a 100 nF X7R ceramic decoupling capacitor as close as possible to both the VBAT (pin 30) and VCC (pin 29) pins, with trace length under 2 mm to limit switching noise injection from the wetting-current sources. According to NXP application guidance, the exposed thermal pad (EP) on the 32-SOIC-EP package must be soldered to a continuous ground copper pour of at least 1 square inch to keep junction temperature within the AEC-Q100 Grade 1 rating when all 22 channels deliver full 32 mA wetting current simultaneously.
Configure the suppressed wake-up mask registers before relying on the INT pin to wake the host MCU, otherwise harness noise and mechanical-switch bounce will generate spurious interrupts that prevent ECU sleep. According to the NXP MC33975 datasheet, per-channel debounce timers are programmable from 1 ms to 32 ms and should be set above the worst-case contact-bounce duration of the mechanical switch being scanned. A common pitfall is leaving debounce at the default minimum value, which causes frequent false wake-ups in body-control modules deployed in real vehicles.
The switch input traces on the PCB are direct antenna entry points for automotive EMI; keep SG0-SG21 traces short, route them away from switching power and motor driver traces, and add a small RC filter (1 kohm + 100 pF typical) at each input if the harness runs more than 200 mm. According to NXP application notes, the on-chip wetting-current source generates common-mode noise that can couple to adjacent analog circuits; provide a solid ground reference plane under the switch matrix routing area to suppress this coupling.
Compliance Information
AEC-Q100 Grade 1 qualified per the NXP MC33975 datasheet. RoHS compliant and Lead Free per distributor listings. Halogen-free status not explicitly stated in the verified web data; consult the NXP material declaration for confirmation.
