PCA9704PW/Q900 - 8-bit SPI GPI 18V Tolerant | NXP
부품 번호: PCA9704PW/Q900 ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
PCA9704PW/Q900 개요
A general-purpose input expander is an interface IC that offloads switch or status-signal monitoring from a microcontroller. In the signal-chain hierarchy, the PCA9704 sits between discrete switch contacts and an MCU's SPI peripheral: GPIO expander -> interface IC -> mixed-signal logic device. Input expanders are used when an MCU lacks sufficient input pins or when switch signals sit at voltages higher than the MCU supply, as is common in automotive 12 V and 24 V electrical systems.
Key features include eight input channels each tolerant to 18 V, allowing direct connection to battery-referenced switch contacts without external level shifting or clamping networks. The SPI interface supports read-out at up to 5 MHz, and a maskable interrupt output (INT) alerts the host controller only when inputs change, enabling low-power polled or event-driven system architectures.
Technically, the PCA9704 is implemented as a parallel-in serial-out shift register with input latching. When the host asserts the chip-select, the current input state is latched and shifted out on the SPI data line; devices can be cascaded to expand beyond eight inputs on a single SPI bus. The /Q900 suffix denotes NXP's automotive product-line extension with AEC-Q100 compliance and PPAP support, distinguishing it from the commercial-grade PCA9704PW.
Typical applications include automotive switch monitoring (door, seat, and key contacts), industrial control-panel status readback, and system diagnostics where battery-level fault or presence signals must be safely captured by a low-voltage controller.
Design consideration: although the 18 V tolerance removes the need for input dividers, verify worst-case battery load-dump transients in automotive systems and confirm that the interrupt mask register is initialized before enabling INT to avoid spurious wake-ups at power-up.
This page synthesizes distributor data, automotive-grade alternative options, and practical SPI integration notes not found in the manufacturer datasheet, with pricing verified as of 2026-10-19.
드롭인 대체품: PCA9704PW/Q900 — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
PCA9704PW
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
PCA9704PW/Q900J
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
PCA9704PW/Q900 사양
| 기능 | 8-bit SPI General Purpose Input (GPI) shift register |
| Number of Input Channels | 8 (input only) |
| Input Voltage Tolerance | 18 V |
| 인터페이스 유형 | SPI |
| Maximum SPI Clock Frequency | 5 MHz |
| Interrupt Output | Yes (maskable INT) |
| Cascadable | Yes (multiple devices on one SPI bus) |
| Qualification | AEC-Q100 compliant (automotive grade, /Q900) |
| 동작 온도 | -40C to +125C (AEC-Q100 Grade 1 range) |
| 패키지 | TSSOP-16 (PW) |
| 실장 유형 | Surface Mount |
| Typical Application | Switch input status monitoring |
| Power Characteristic | Low power |
| Manufacturer Suffix Meaning | /Q900 = automotive product line with PPAP support |
PCA9704PW/Q900 tssop-16 (pw) 핀 구성 가이드
PCA9704PW/Q900(tssop-16 (pw) 패키지)의 핀 구성입니다. 핀 번호, 기능, 연결 다이어그램은 제조사 데이터시트에 정의되어 있습니다. 정확한 풋프린트와 솔더링 지침은 해당 문서를 참조하십시오.
다음에 대한 상세 핀아웃 데이터 없음: PCA9704PW/Q900.
다음을 참조하십시오: 데이터시트 전체 핀 구성은 다음을 참조하십시오.
일반적인 애플리케이션
PCA9704PW/Q900 적합 용도: 6 애플리케이션s: Automotive Switch Input Monitoring, Industrial Control Panel Status Readback, System Diagnostics and Fault Capture, Battery-Powered and Low-Power Sensor Nodes, Automotive Key and Access Systems, Cascade GPIO Expansion Beyond Eight Inputs.
Automotive Switch Input Monitoring
The PCA9704PW/Q900 fits automotive switch monitoring directly: its eight inputs are each tolerant to 18 V, so door, seat, key, and hood contacts referenced to a 12 V battery bus connect without dividers or clamp networks, and the AEC-Q100 qualification plus -40C to +125C operation satisfies body-electronics qualification requirements. In use, the device latches switch state on chip-select and shifts it to the body controller over SPI at up to 5 MHz, reading all eight channels in microseconds. The maskable INT output enables event-driven wake-up so the MCU can sleep until a contact changes, a significant current saving in always-on vehicle systems. The main trade-off is power dissipation through input protection structures when inputs sit high, which is negligible at these currents.
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Industrial Control Panel Status Readback
Industrial 24 V control panels present the same problem the PCA9704PW/Q900 solves: many switch, relay-auxiliary, and limit-switch signals sitting near 24 V that a 3.3 V or 5 V PLC controller cannot touch directly. The 18 V tolerant inputs handle most 24 V-referenced contact conditions via appropriate series consideration, and eight channels per TSSOP-16 device yields high monitoring density on a small footprint. Reading is a single SPI transaction at up to 5 MHz; cascading several PCA9704 devices on one chip-select expands to 16, 24, or 32 inputs with no extra controller pins. The maskable interrupt supports fault-first architectures where the PLC is interrupted only on status change. Select this part when density, isolation-free simplicity, and interrupt-driven polling outweigh the need for galvanic isolation, which must be added separately where safety codes require it.
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System Diagnostics and Fault Capture
Diagnostic subsystems must capture battery-referenced fault, presence, and interlock signals safely and timestamp them precisely. The PCA9704PW/Q900's 18 V tolerant inputs accept these signals directly, while the input latching on chip-select guarantees a coherent, glitch-free snapshot of all eight channels per SPI read - important when correlating fault events across channels. The 5 MHz SPI lets a diagnostic MCU poll every few microseconds during a fault window, effectively building a coarse logic-analyzer trace of switch behavior. AEC-Q100 compliance allows the same diagnostic design to be reused across automotive and industrial platforms without respin. Designers should initialize the interrupt mask register before enabling INT so pre-existing fault states at power-up do not generate spurious alerts, and should verify worst-case signal swing against the 18 V absolute maximum in load-dump conditions.
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Battery-Powered and Low-Power Sensor Nodes
The PCA9704 is explicitly characterized by NXP as a low-power device, which combined with the maskable INT output makes it well suited to battery-powered nodes that must watch eight switch or sensor-presence inputs without continuous polling. In the recommended topology, the MCU sleeps with only the INT line armed; any masked input change asserts INT and wakes the controller, which then clocks out the input state over SPI at up to 5 MHz in a few microseconds before returning to sleep. This event-driven duty cycle reduces average system current to the expander's low quiescent draw plus interrupt-line leakage. The 18 V tolerance further simplifies power-system design by letting switch signals come straight from the raw battery rail rather than a regulated domain. Confirm the exact quiescent current figure in the NXP datasheet for your battery-budget calculation.
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Automotive Key and Access Systems
Key switches, door-lock switches, and immobilizer presence contacts are classic 12 V-referenced inputs in vehicles, and the PCA9704PW/Q900 was designed for exactly this: NXP describes it as an 18 V tolerant SPI GPI shift register for monitoring switch-input status, with AEC-Q100 compliance for the automotive environment. Eight channels per device covers a complete door set - lock, unlock, key-in, and door-ajar per side - and the maskable INT lets the body controller wake only on a genuine key action, supporting the low standby current demanded of modern vehicles. Reads over 5 MHz SPI complete fast enough for debouncing entirely in MCU firmware at standard tick rates. The TSSOP-16 package suits compact body-control modules. For safety-critical access functions, add external filtering of contact bounce and verify behavior under cranking transients below the 18 V input ceiling.
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Cascade GPIO Expansion Beyond Eight Inputs
When a design must monitor 16, 24, or more switch inputs, multiple PCA9704PW/Q900 devices can be cascaded on a single SPI chip-select: each device latches its inputs and shifts its data through the chain, so one 5 MHz SPI transaction reads the entire bank coherently. This architecture conserves controller pins - only CS, SCK, and two data lines are needed regardless of channel count - and keeps firmware simple because the concatenated bit-stream maps directly to input order. Since all devices share one chip-select, all inputs latch simultaneously, which is valuable for time-correlated status capture in industrial sequencers and test fixtures. The 18 V tolerance applies at every channel, so mixed 12 V and 24 V signal domains can coexist on the same chain. Budget SPI transaction time at 5 MHz for the total bit count when sizing polling rates.
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추천 제품 요약
엔지니어링 참조 데이터: PCA9704PW/Q900 — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | PCA9704PW | PCA9704PW/Q900J |
|---|---|---|---|
| Package | TSSOP-16 (PW) | TSSOP-16 (PW) - same | TSSOP-16 (PW) - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Input Channels | 8 (input only) | 8 (input only) | 8 (input only) |
| Input Voltage Tolerance | 18 V | 18 V | 18 V |
| Max SPI Clock | 5 MHz | 5 MHz | 5 MHz |
| Maskable Interrupt | Yes | Yes | Yes |
| AEC-Q100 Qualified | Yes (/Q900 automotive line) | No (commercial grade) | Yes (automotive) |
주요 차별점
- AEC-Q100 automotive qualification with PPAP support (vs PCA9704PW)
- 18 V tolerant inputs eliminate level-shifting circuitry (vs PCA9704PW)
- Maskable interrupt enables low-power event-driven designs (vs PCA9704PW/Q900J)
설계 노트
Initialize the interrupt mask register before enabling the INT output in your SPI init sequence. At power-up the input latches contain an undefined snapshot of the switch state; if INT is enabled before masking, stale or transitioning inputs can generate a spurious interrupt that wakes the controller unnecessarily or, in diagnostics, logs a phantom fault. A recommended pattern is: assert CS, write the mask, clear any pending INT, then enable the host interrupt controller.
Although the 18 V tolerance removes the need for input dividers, automotive battery rails experience load-dump and cranking transients that can exceed the 18 V absolute maximum. For direct battery-referenced contacts, add series resistance on each input per the datasheet recommendation and verify your module-level transient specification (e.g., ISO pulse profiles required by your OEM) against the 18 V ceiling. If your system sees sustained voltages above 18 V, external clamping is required.
Keep the SPI traces (CS, SCK, data) short and route them away from switch lines carrying battery-level signals; the 18 V tolerant inputs are robust, but coupling of fast transients from adjacent high-voltage switch lines into the SPI bus can cause read errors at 5 MHz. Place 100 nF decoupling as close as possible to the VDD pin. When cascading devices, treat the daisy-chain data line as a point-to-point routed net rather than a long stub bus to preserve timing margin.
규정 준수 정보
AEC-Q100 compliance is explicitly stated on the NXP product page and distributor listings for the /Q900 automotive product line. RoHS/REACH status should be confirmed on the NXP PCA9704PW product page quality tab.
