MC33978EK - 22-Channel MSDI, SPI, 36V SMARTMOS | NXP
N.º de pieza: MC33978EK ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $5.42 | $5,42 |
| 10 | $4.85 | $48,50 |
| 100 | $4.21 | $421,00 |
| 500 | $3.68 | $1.840,00 |
| 1.000 | $3.15 | $3.150,00 |
| 3.000 | $2.74 | $8.220,00 |
MC33978EK Descripción general
What is a Multiple Switch Detection Interface (MSDI)? An MSDI is a specialized mixed-signal interface IC in the SMARTMOS power-management family that scans and debounces a large number of mechanical or electronic switch contacts (typical automotive body controllers require 10-30 discrete inputs). It replaces dozens of discrete pull-ups, comparators, and MCU GPIO with a single SPI-controlled device, providing programmable wetting current, programmable threshold, and integrated analog multiplexing. In the broader taxonomy, the MC33978EK belongs to switch detection interface IC -> body/comfort network interface IC -> power management and system basis IC -> mixed-signal semiconductor.
Key features include 22 input channels (14 switch-to-ground SG plus 8 programmable SG/SB), 7-level selectable wetting current (2/6/8/10/12/14/16/20 mA), selectable wake-up on change of state, an integrated 24-to-1 analog multiplexer with buffered output, and a configurable 4.0V input comparator threshold. The exposed pad (EP) of the SOICW-EP package provides a low thermal resistance path, while the wide 4.5-36V input range survives automotive load-dump transients.
Architecturally, the device uses SMARTMOS mixed-signal BiCMOS with on-chip non-volatile trimming, an SPI-protocol engine, and current sources that source programmable wetting current into each switch contact. The 24-to-1 analog MUX allows one ADC channel on the MCU to digitize any of the 22 inputs plus internal supplies, reducing MCU pin count and BOM.
Typical applications include automotive body control modules reading door/window/seat switches, steering-wheel switch matrices, HVAC control panels, and any 12V/24V industrial system with many low-frequency switch contacts. When designing with this device, ensure the wetting current is sized for the contact material and keep the SPI traces short; the EP pad must be soldered to a copper pour for thermal relief and electrical ground.
Alternativas directas para MC33978EK — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
MC33978AEK
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MC33978EKR2
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MC34978EK
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MC33978AEKR2
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MC33978EFR2
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MC33978EK Especificaciones
| Función | 22-channel Multiple Switch Detection Interface (MSDI) |
| Number of Switch Channels | 22 (14 SG + 8 programmable SG/SB) |
| Interfaz | SPI (3.3 V / 5.0 V) |
| Operating Voltage (Full Function) | 4.5 V to 36 V |
| Operating Voltage (Full Parametric) | 6.0 V to 28 V |
| Low-Power Mode Current IBATP | 30 uA |
| Low-Power Mode Current IDDQ | 10 uA |
| Wetting Current Levels | 2, 6, 8, 10, 12, 14, 16, 20 mA (selectable) |
| Input Comparator Threshold | 4.0 V (configurable) |
| Analog MUX | 24-to-1 with buffered output |
| Wake-up Capability | Selectable wake-up on change of state |
| Encapsulado | 32-pin SOICW-EP (exposed pad) |
| Tipo de montaje | Surface Mount |
| Temperatura de funcionamiento | -40 C to +125 C |
| Estado RoHS | Compliant |
| Technology Family | SMARTMOS mixed-signal |
Configuración de pines de MC33978EK
| Pin 1 | VBATP — Battery supply voltage (4.5 V to 36 V) |
| Pin 2 | VDD — Logic supply (3.3 V or 5 V) |
| Pin 3 | GND — Ground |
| Pin 4 | RESET — Reset input (active low) |
| Pin 5 | CS — SPI chip select (active low) |
| Pin 6 | SCLK — SPI clock |
| Pin 7 | MOSI — SPI master-out slave-in |
| Pin 8 | MISO — SPI master-in slave-out |
| Pin 9 | INT — Interrupt output (wake-up) |
| Pin 10 | AMUX — Analog multiplexer output (24-to-1) |
| Pin 11 | SP0 — Switch-to-ground input 0 |
| Pin 12 | SP1 — Switch-to-ground input 1 |
| Pin 13 | SP2 — Switch-to-ground input 2 |
| Pin 14 | SP3 — Switch-to-ground input 3 |
| Pin 15 | SP4 — Switch-to-ground input 4 |
| Pin 16 | SP5 — Switch-to-ground input 5 |
| Pin 17 | SP6 — Switch-to-ground input 6 |
| Pin 18 | SP7 — Switch-to-ground input 7 |
| Pin 19 | SP8 — Switch-to-ground input 8 |
| Pin 20 | SP9 — Switch-to-ground input 9 |
| Pin 21 | SP10 — Switch-to-ground input 10 |
| Pin 22 | SP11 — Switch-to-ground input 11 |
| Pin 23 | SP12 — Switch-to-ground input 12 |
| Pin 24 | SP13 — Switch-to-ground input 13 |
| Pin 25 | SP14 — Programmable SG/SB input 14 |
| Pin 26 | SP15 — Programmable SG/SB input 15 |
| Pin 27 | SP16 — Programmable SG/SB input 16 |
| Pin 28 | SP17 — Programmable SG/SB input 17 |
| Pin 29 | SP18 — Programmable SG/SB input 18 |
| Pin 30 | SP19 — Programmable SG/SB input 19 |
| Pin 31 | SP20 — Programmable SG/SB input 20 |
| Pin 32 | SP21 — Programmable SG/SB input 21 |
Aplicaciones típicas
MC33978EK es adecuado para 6 aplicacións: Automotive Body Control Module (BCM), Steering Wheel Switch Matrix Reading, HVAC Control Panel Switch Detection, Industrial Control Panel Switch Monitoring, Agricultural / Off-Highway Vehicle Switch Panels, Appliance and White-Goods Switch Interface.
Automotive Body Control Module (BCM)
The MC33978EK is purpose-built for automotive body control modules that monitor dozens of switch contacts: door ajar, trunk, hood, window up/down, mirror adjust, and seat-position switches. With 22 channels (14 SG + 8 programmable SG/SB), a single IC replaces discrete pull-up resistor networks, saving PCB area and BOM. The 4.5V to 36V input range tolerates load-dump transients on the 12V automotive bus, and the 30 uA low-power current keeps BCM quiescent drain under typical OEM <100 uA budgets. The integrated 24-to-1 analog MUX allows the host MCU to read any switch as an analog voltage (for ratiometric position sensing) using a single ADC channel.
Recomendado
Steering Wheel Switch Matrix Reading
Modern steering wheels integrate 6-10 momentary switches for audio, cruise, and phone controls; these need to be read reliably through a clock-spring harness with limited conductors. The MC33978EK's SPI interface concentrates 22 switch states into 4 wires (MOSI/MISO/SCLK/CS), eliminating the clock-spring pin count problem. Programmable wetting current (2-20 mA) prevents contact oxidation in the high-vibration steering-wheel environment, and the 4.0V programmable comparator threshold rejects noise coupled from the audio/HVAC harness. Wake-up-on-change-of-state allows the steering-wheel logic to wake the body MCU only when the driver actually presses a button.
Recomendado
HVAC Control Panel Switch Detection
Automotive HVAC head units contain 15-25 mechanical switches (temperature up/down, fan speed, mode, defrost, recirculation) plus rotary encoders. The MC33978EK replaces the entire analog switch-scan matrix with a single SPI device, simplifying the front-panel flex-circuit and reducing ESD failure modes. The 8 programmable SG/SB inputs can read switch-to-battery signals from the HVAC mode selector, while the 14 dedicated SG inputs handle the high-density button matrix. Wide operating temperature (-40C to +125C) covers the under-dash thermal environment, and the SOICW-EP package's exposed pad handles thermal dissipation without a heatsink.
Recomendado
Industrial Control Panel Switch Monitoring
Industrial machinery panels and operator consoles need to read many pushbuttons, limit switches, and selector switches over a 24V supply rail. The MC34978EK variant (24V industrial, same SOICW-EP footprint) is the preferred part here, but the MC33978EK also functions on 24V supplies within its parametric 6.0-28V range. Programmable wetting current keeps contacts clean in dusty industrial environments, and the SPI interface reduces the I/O count on the host PLC or industrial MCU. Low-power mode (30 uA on VBATP) supports battery-backed industrial controllers that must sleep between operator inputs.
Recomendado
Agricultural / Off-Highway Vehicle Switch Panels
Tractors, combine harvesters, and construction equipment use 24V electrical systems with harsh EMC environments. The MC34978EK variant (6.0-58V supply) pairs with the MC33978EK family firmware for switch reading in these vehicles, sharing the same SPI register map so one MCU firmware supports both 12V and 24V variants. The 22-channel count covers joystick buttons, PTO engagement switches, diff-lock switches, and hydraulic-mode selectors. The exposed-pad SOICW-EP package provides mechanical robustness against the high-vibration agricultural environment, and the 30 uA sleep current is critical for tractor battery management during off-season storage.
Recomendado
Appliance and White-Goods Switch Interface
High-end washing machines, dishwashers, and ovens use 15-30 capacitive or mechanical switches plus rotary encoders. The MC33978EK, with its 22-channel count and SPI interface, replaces the discrete button-scan matrix and reduces the main controller's GPIO load. Programmable wetting current is not needed for low-current logic-level switches (use 2 mA), and the wide supply range (4.5-36V) tolerates rectified mains-rail variations in appliances without an additional regulator. Wake-on-change-of-state enables sub-100 uA standby for ENERGY STAR compliance.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para MC33978EK — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | MC33978AEK | MC33978EKR2 | MC34978EK | MC33978AEKR2 | MC33978EFR2 |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 32-SOICW-EP | 32-SOICW-EP - same | 32-SOICW-EP - same | 32-SOICW-EP - same | 32-SOICW-EP - same | 32-SOICW-EP - same |
| Function | 22-ch MSDI, 14 SG + 8 SG/SB | 22-ch MSDI, 14 SG + 8 SG/SB | 22-ch MSDI, 14 SG + 8 SG/SB | 22-ch MSDI, 14 SG + 8 SG/SB | 22-ch MSDI, 14 SG + 8 SG/SB | 22-ch MSDI, 14 SG + 8 SG/SB |
| Operating Voltage Range | 4.5 V to 36 V | 4.5 V to 36 V | 4.5 V to 36 V | 6.0 V to 58 V (24V/industrial) | 4.5 V to 36 V | 4.5 V to 36 V |
| Wetting Current Levels | 2, 6, 8, 10, 12, 14, 16, 20 mA | 2, 6, 8, 10, 12, 14, 16, 20 mA | 2, 6, 8, 10, 12, 14, 16, 20 mA | 2, 6, 8, 10, 12, 14, 16, 20 mA | 2, 6, 8, 10, 12, 14, 16, 20 mA | 2, 6, 8, 10, 12, 14, 16, 20 mA |
| Low-Power Current IBATP | 30 uA | 30 uA | 30 uA | 30 uA | 30 uA | 30 uA |
| SPI Interface Voltage | 3.3 V / 5.0 V | 3.3 V / 5.0 V | 3.3 V / 5.0 V | 3.3 V / 5.0 V | 3.3 V / 5.0 V | 3.3 V / 5.0 V |
| Analog MUX | 24-to-1 buffered | 24-to-1 buffered | 24-to-1 buffered | 24-to-1 buffered | 24-to-1 buffered | 24-to-1 buffered |
| Revision / Errata Status | Legacy EK (errata ER01) | Current revision, all errata fixed | Legacy EK + tape-and-reel | 24V industrial variant | Current AEK + tape-and-reel | Pre-programmed config variant |
| Application Target | 12V automotive | 12V automotive | 12V automotive (high volume) | 24V industrial / off-highway | 12V automotive (high volume) | 12V automotive (pre-programmed) |
Diferenciadores clave
- Industry-leading 22 channels in a single IC (frente a Discrete pull-up resistor + comparator network)
- Programmable wetting current keeps contacts clean (frente a Discrete design with fixed pull-up resistor)
- Integrated 24-to-1 analog multiplexer with buffered output (frente a External analog switch IC (e.g., CD4051))
- 30 uA low-power current with wake-on-change-of-state (frente a Polled discrete inputs requiring always-on MCU)
Notas de diseño
VBATP must be decoupled with a 100 nF X7R ceramic placed within 5 mm of the VBATP pin and a bulk 10 uF tantalum or aluminum-polymer capacitor on the supply rail. Per the NXP datasheet, the device tolerates load-dump transients to 36 V but does not include reverse-battery protection; add an external SMBJ24CA TVS or P-MOSFET reverse-polarity block if the harness can be miswired. VDD (logic supply) requires its own 100 nF + 1 uF decoupling pair.
The SOICW-EP exposed pad is the primary thermal path; it must be soldered to a copper pour of at least 100 mm^2 on the top layer, plus thermal vias to inner/outer ground planes (recommended 4-9 vias, 0.3 mm drill, 0.6 mm pad). Without the EP properly soldered, theta_JA rises by 30-40 C/W, potentially exceeding 125 C junction at full wetting-current load. The exposed pad is also the electrical ground reference for the device; an unsoldered EP can cause SPI communication errors and wetting-current drift.
MC33978EK is subject to errata MC33978ER ER01 (specific current-leakage conditions on certain pins); for new designs choose MC33978AEK or MC33978AEKR2. Do not mix the EK and AEK silicon revisions on the same SPI bus without verifying register compatibility, although the SPI protocol is identical. Always configure unused SPx pins as 'not connected' (NC) in firmware; floating inputs can false-trigger the wake-up interrupt and drain the 30 uA sleep budget.
Keep SPI traces (CS, SCLK, MOSI, MISO, INT) under 50 mm total length and away from the SPx switch-input traces to avoid capacitive coupling from the high-impedance switch lines. Place a 10 kohm pull-up on CS to prevent floating-chip-select glitches; place a 100 kohm pull-up on INT if the MCU edge-trigger is configured for rising-edge only. The 24-to-1 analog MUX output (AMUX pin) should drive a short trace to the MCU ADC input; add a 1 nF buffer cap if the ADC sample rate is below 100 kS/s to prevent kickback noise.
Información de cumplimiento
AEC-Q100 qualified per NXP SMARTMOS product family. RoHS and REACH compliant per NXP product page. Halogen-free status not explicitly stated in the verified data.
