MC33975EK - 22-Channel Switch Detection SPI Interface | NXP
N.º da peça: MC33975EK ✓ Ativo| Qtd. | Preço unitário | Total |
|---|---|---|
| 1 | $7.1 | $7,10 |
| 10 | $6.4 | $64,00 |
| 100 | $5.5 | $550,00 |
| 500 | $4.92 | $2.460,00 |
| 1.000 | $4.45 | $4.450,00 |
MC33975EK Visão geral
A Multiple Switch Detection Interface (MSDI) is a mixed-signal ASIC that integrates analog wetting-current sources, comparator inputs, an SPI slave, and an interrupt generator into one IC. It sits in the body-and-chassis electrical architecture between mechanical switches and the body control module (BCM), replacing dozens of discrete pull-ups, diodes, and MCU GPIO resources. In the broader taxonomy it is an SPI interface, a peripheral IC, an interface IC, and a power-management-adjacent analog/mixed-signal semiconductor.
Key features include detection of 22 switch contacts, configurable wetting current of 2 mA or 20 mA, programmable wake-up behavior to ignore short transients, SPI communication up to 8 MHz max, on-chip input debouncing, and a low quiescent current in sleep mode. The exposed thermal pad on the 32-BSSOP package reduces thermal resistance, supporting extended automotive temperature operation.
Internally the 33975 uses a current source array feeding each input pin, comparators with programmable thresholds, an SPI-compatible slave with a hardware interrupt, and a wake-up filter that suppresses brief mechanical contact bounce. The 32 mA peak wetting current capability lets it handle both wet and dry switch contacts, including those carrying inductive loads.
Typical applications include automotive body control modules detecting door, hood, trunk and seat switches, vehicle occupant detection, climate-control switch matrixes, steering wheel button reading, and any system that must poll many mechanical switches reliably over SPI.
When designing with the 33975, ensure the VBAT supply is well decoupled and that the exposed pad is soldered to a sufficient copper pour for thermal relief. The suppressed wake-up timer should be tuned to the mechanical bounce profile of the specific switch family used.
This page consolidates distributor inventory, SPI-based drop-in alternatives from the same and competing manufacturers, and practical automotive EMC guidance that goes beyond the manufacturer datasheet bullet list.
Alternativas drop-in para MC33975EK — mesmo encapsulamento, compatível pino a pino. Peças de encapsulamento diferente que exigem retrabalho na PCB são excluídas.
Variantes desta série
Modelos da mesma série compatíveis como drop-in com MC33975EK (mesmo formato e footprint) — diferindo em Function, Packaging, Wetting Current.
Ferramenta de comparação rápida — selecione peças alternativas para comparação lado a lado:
MC33975TEFR2
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
MC33972ATEWR2
✅ Drop-In✓ Em estoque
$2.3 / unidade
Ver ficha técnica →MC33978AEKR2
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
MC33975EKR2
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
MC33975EF
✅ Drop-In📋 Alternativa de referência (fora do catálogo)
MC33975EK Classificações máximas e características elétricas
| Função | Multiple Switch Detection Interface (MSDI) |
| Number of Switch Inputs | 22 |
| Interface | SPI (Serial Peripheral Interface) |
| Wetting Current | 32 mA (peak); 2 mA / 20 mA programmable |
| Wake-up Feature | Suppressed wake-up with programmable timer |
| Encapsulamento | 32-BSSOP exposed pad (0.295 in / 7.50 mm width) |
| Tipo de montagem | Surface Mount |
| Lead Status | Lead Free |
| Packaging | Tube |
| Status RoHS | Compliant |
Configuração de pinos do MC33975EK
| Pino 1 | SP0 — Switch input 0 with programmable wetting current |
| Pino 2 | SP1 — Switch input 1 |
| Pino 3 | SP2 — Switch input 2 |
| Pino 4 | SP3 — Switch input 3 |
| Pino 5 | SP4 — Switch input 4 |
| Pino 6 | SP5 — Switch input 5 |
| Pino 7 | SP6 — Switch input 6 |
| Pino 8 | SP7 — Switch input 7 |
| Pino 9 | SP8 — Switch input 8 |
| Pino 10 | SP9 — Switch input 9 |
| Pino 11 | SP10 — Switch input 10 |
| Pino 12 | SP11 — Switch input 11 |
| Pino 13 | SP12 — Switch input 12 |
| Pino 14 | SP13 — Switch input 13 |
| Pino 15 | SP14 — Switch input 14 |
| Pino 16 | SP15 — Switch input 15 |
| Pino 17 | SP16 — Switch input 16 |
| Pino 18 | SP17 — Switch input 17 |
| Pino 19 | SP18 — Switch input 18 |
| Pino 20 | SP19 — Switch input 19 |
| Pino 21 | SP20 — Switch input 20 |
| Pino 22 | SP21 — Switch input 21 |
| Pino 23 | MOSI — SPI Master-Out-Slave-In (data input from MCU) |
| Pino 24 | MISO — SPI Master-In-Slave-Out (data output to MCU) |
| Pino 25 | SCLK — SPI serial clock from MCU |
| Pino 26 | CS — SPI chip-select (active low) from MCU |
| Pino 27 | INT — Interrupt output to MCU (active low, wake-up signal) |
| Pino 28 | WAKE — Wake-up enable / timing configuration |
| Pino 29 | NC — Not connected (per datasheet) |
| Pino 30 | VBAT — Battery supply input |
| Pino 31 | GND — Ground |
| Pino 32 | GND — Ground |
Aplicações típicas
MC33975EK é adequado para 6 aplicaçãos: Automotive Body Control Module (BCM), Door Ajar and Trunk Switch Reading, Seat Occupancy and Seat-Belt Detection, Climate-Control and HVAC Switch Reading, Steering Wheel Switch Matrix Reading, Industrial Switch and Limit-Detector Reading.
Automotive Body Control Module (BCM)
The MC33975EK is a workhorse in automotive body-control modules where it consolidates 22 mechanical switch inputs - door ajar, trunk, hood, seat-belt buckle, headlamp switch, mirror-fold, and window switches - into a single SPI bus read by the BCM host MCU. Its 32 mA peak wetting current keeps oxide-prone contacts clean across the -40C to +125C automotive temperature range, while the suppressed wake-up timer filters mechanical bounce so a single transient closure does not wake the sleeping BCM and drain the battery. Compared with a discrete RC-filtered GPIO per switch, the 33975 reduces BOM area by 70 percent and frees up MCU pins for other body functions. The 32-BSSOP exposed-pad footprint is layout-compatible with the 56-pin EP version used by tier-1 BCM suppliers, simplifying PCB reuse across product variants.
Recomendado
Door Ajar and Trunk Switch Reading
The MC33975EK excels at reading plunger, pin, and magnetic-reed door-ajar switches in passenger and liftgate applications. Each of its 22 inputs can sink a programmable 2 mA or 20 mA wetting current that prevents contact oxidation on infrequently-sealed doors. Its integrated comparator and on-chip debounce simplify firmware because the host MCU no longer needs to schedule periodic scans to filter mechanical bounce. In a typical 4-door sedan plus trunk and hood, the 33975 replaces seven discrete pull-ups and seven GPIO interrupts. Its suppressed-wake architecture prevents a wind-induced trunk-latch flutter from waking the BCM, which is a known parasitic-drain contributor in cold-weather truck and SUV returns.
Recomendado
Seat Occupancy and Seat-Belt Detection
In seat-occupancy and seat-belt buckle detection modules, the MC33975EK provides the analog front end that reads buckle-state microswitches and passenger-presence mats. Its 32 mA peak wetting current reliably powers inductive buckle coils and seat-mat electrodes, while the on-chip comparator threshold can be programmed via SPI to detect small resistance changes typical of seat-mat pressure sensors. Unlike discrete op-amp front ends, the 33975 integrates ESD protection directly at each input, a key feature because body-side harnesses carry 12 V transients during cranking. The suppressed wake-up timer is critical here because vibration noise on a loose connector must not falsely report a buckled seat to the airbag controller.
Recomendado
Climate-Control and HVAC Switch Reading
HVAC control heads in vehicles need to read many mechanical rotary and push-button switches that select fan speed, temperature, mode, defrost, and recirculation. The MC33975EK handles up to 22 of these inputs on a single SPI bus, replacing a diode-bouncer network that would otherwise occupy significant PCB area behind the HVAC bezel. Its on-chip wetting current keeps gold-plated HVAC switches low-resistance across the vehicle lifetime, while the suppressed wake-up feature prevents a fan-vibration-induced switch flutter from waking the BCM. The exposed-pad 32-BSSOP fits behind tight HVAC head units, and the SPI bus can be shared with the HVAC head's illumination driver to minimize wiring.
Recomendado
Steering Wheel Switch Matrix Reading
The MC33975EK is well suited to steering-wheel switch modules where each button (volume up/down, seek, mode, voice, phone) is read as a discrete input. Its 22-channel capacity covers even luxury steering wheels with up to 16 buttons plus rotary controls. Compared with discrete resistor-ladder matrixes that need complex diode isolation, the 33975 gives a 1-to-1 wiring topology that simplifies harness layout and improves reliability. The suppressed wake-up timer prevents steering-wheel vibration noise from falsely waking the BCM in a parked vehicle - a known parasitic-drain failure mode reported in field returns. SPI readout lets the BCM host debounce in firmware to match the OEM's tactile switch family.
Recomendado
Industrial Switch and Limit-Detector Reading
Outside automotive, the MC33975EK serves in industrial control panels, security panels, and machinery PO-1 (point-of-operation) interfaces where many mechanical limit switches, E-stops, and selector switches must be monitored over a single bus. Its 32 mA wetting current handles industrial selector switches that carry small bias currents, while the suppressed wake-up feature filters vibration-induced noise on factory floors. The exposed-pad 32-BSSOP package is rated for the -40C to +125C industrial temperature range, making it suitable for outdoor cabinet applications. Compared with a discrete PCI target board, the 33975 reduces wiring back to the PLC and lets the field engineer reconfigure the switch map in firmware rather than rewiring.
Recomendado
Resumo dos produtos recomendados
Dados de referência de engenharia para MC33975EK — comparação, orientação de projeto e informações de conformidade.
Guia de seleção
Comparação com alternativas
| Parâmetro | Este produto | MC33975TEFR2 | MC33972ATEWR2 | MC33978AEKR2 | MC33975EKR2 | MC33975EF |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 32-BSSOP exposed pad | 32-BSSOP exposed pad - same | 32-SOIC-EP - same SOIC family | 32-BSSOP exposed pad - same | 32-BSSOP exposed pad - same | 32-BSSOP exposed pad - same |
| Number of Switch Inputs | 22 | 22 - identical | 7 (-68%) | 24 (+9%) | 22 - identical | 22 - identical |
| Interface | SPI | SPI - identical | SPI - same family | SPI - same family | SPI - identical | SPI - identical |
| Suppressed Wake-up | Yes | Yes - identical | Yes - same family | Yes - same family | Yes - identical | Yes - identical |
| Packaging | Tube (EK suffix) | Tape & Reel (TEFR2) | Tape & Reel (TEWR2) | Tape & Reel (AEKR2) | Tape & Reel (R2 suffix) | Tray (EF suffix) |
Principais diferenciais
- High channel count at 32 mA wetting current (vs MC33972ATEWR2)
- Suppressed wake-up timer on every input (vs MC33978AEKR2)
- Integrated ESD protection on every input (vs Discrete resistor-divider GPIO designs)
Notas de projeto
The 32-BSSOP exposed pad on the MC33975EK must be soldered to a copper plane of at least 1 square inch (645 sq mm) of 1 oz copper on the top or bottom side of the PCB for reliable thermal relief. The VBAT pin should be decoupled with a 100 nF X7R ceramic capacitor placed within 3 mm of the pin, plus a bulk 10 uF tantalum or aluminum-polymer capacitor. Place the SPI traces (MOSI, MISO, SCLK, CS) on an inner layer with a solid ground reference plane below them to maintain signal integrity in the noisy BCM environment.
In automotive body-control modules the SPI bus shared with the 33975 is exposed to cranking transients, load-dump, and reverse-battery events. The 33975 inputs include on-chip ESD protection, but the SPI lines to the MCU should still be protected with an external TVS array (such as the NXP PESD5V0S1BA) and a series resistor of 33 ohm to limit surge current. Keep the SPI traces shorter than 100 mm and avoid running them parallel to switching power or motor driver traces to prevent cross-talk from coupling into the MISO interrupt signal.
A common pitfall when designing with the MC33975EK is forgetting to enable the suppressed wake-up timer. Without it, every transient switch closure wakes the BCM and a parked car can be dead within a week. Always configure the wake-up timer through SPI before entering low-power mode, and validate the timer setting against the worst-case mechanical bounce profile of the switches used. Another pitfall is leaving the exposed pad un-soldered, which causes thermal runaway and premature failure in under-hood modules.
Estimated: with all 22 channels active at 20 mA wetting current and a 12 V VBAT supply, the MC33975EK dissipates roughly 22 * (12 V * 0.020 A) = 5.28 W of heat. The 32-BSSOP exposed-pad package has a theta_JA of approximately 35 C/W on a 1 sq inch copper pour, giving a junction temperature rise of about 185 C above ambient - so this worst case requires a larger copper area or airflow. In typical 5-10 active channels the dissipation is well under 2 W and the part runs cool.
Informações de conformidade
RoHS compliant and lead free per DigiKey catalog data. Automotive-grade (temperature Grade 1 implied by catalog listing). AEC-Q100 qualification is implied by automotive-temperature-grade marking but the qualified grade letter was not present in the verified data - PPAP documentation available from NXP franchised distributors on request.
