PCF8574NG4 - 8-Bit I2C I/O Expander | Texas Instruments
부품 번호: PCF8574NG4 ✓ 활성PCF8574NG4 개요
An I/O expander is an interface IC that extends the number of general-purpose inputs and outputs available to a microcontroller or other host processor. The I2C interface uses serial clock and serial data lines to transfer address and port information, while the parallel port provides individual connections to external hardware. This hierarchy places the PCF8574 within I2C interface controllers, interface ICs, and semiconductor-based system expansion components.
The PCF8574 combines an 8-bit quasi-bidirectional port with an I2C interface. Quasi-bidirectional operation means each port can be used for input or output, with output drivers capable of sinking current while the input state can be detected. An interrupt output provides a way for the host to react when a changing input condition is detected, reducing the need for continuous I2C polling in suitable designs.
The 2.5 V to 6 V VCC range allows the device to operate with both 3.3 V and 5 V system rails. Its 100 kHz I2C maximum supports conventional standard-mode bus operation and broad compatibility with embedded processors. The remote port also reduces the number of GPIO pins required from the host controller, which can simplify pin allocation in compact embedded systems.
Typical uses include relay and solenoid control, keypad and switch sensing, LED or indicator interfaces, sensor input collection, and industrial control panels. The same electrical interface is useful when the remote equipment is physically separated from the host because the PCF8574 communicates through the bus while exposing local input and output connections at the port.
Design with the port's quasi-bidirectional characteristics and the electrical limits in the manufacturer datasheet in mind. Pull-up requirements, address selection, bus capacitance, output-driver topology, and reset behavior must be checked against the specific system. Do not assume that every quasi-bidirectional port can source the same current that it can sink.
This page combines the manufacturer electrical operating range, package details, pin-level guidance, and application-oriented analysis with a focused comparison of verified same-package alternatives. It also identifies design trade-offs that are not obvious from a distributor category listing, helping engineers determine whether the 16-pin PCF8574NG4 remains suitable for a new embedded interface design.
드롭인 대체품: PCF8574NG4 — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
이 시리즈의 변형
다음과 드롭인 호환되는 동일 시리즈 모델: PCF8574NG4 (동일 폼 팩터 및 풋프린트) — 차이점: Interface, Package, Supply Voltage Range.
PCF8574N
✅ 드롭인가격 문의
데이터시트 보기 →PCF8574P,112
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
PCF8574AP,112
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
PCF8574ANG4
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
PCF8574NG4 사양
| Device Type | 8-bit I/O expander |
| 인터페이스 | I2C |
| Bus Frequency | 100 kHz |
| Supply Voltage Range | 2.5 V to 6 V |
| Number of I/O Lines | 8 lines |
| Port Type | 8-bit quasi-bidirectional |
| Bus Type | Two-line bidirectional |
| 패키지 | 16-DIP (0.300 inch, 7.62 mm) |
| 핀 수 | 16 pins |
| Lead Pitch | 7.62 mm |
| 실장 유형 | Through-hole |
| Interrupt Output | 1 open-drain interrupt output |
PCF8574NG4 핀 구성
| 핀 1 | P0 — Quasi-bidirectional I/O port line 0 |
| 핀 2 | P1 — Quasi-bidirectional I/O port line 1 |
| 핀 3 | P2 — Quasi-bidirectional I/O port line 2 |
| 핀 4 | P3 — Quasi-bidirectional I/O port line 3 |
| 핀 5 | P4 — Quasi-bidirectional I/O port line 4 |
| 핀 6 | P5 — Quasi-bidirectional I/O port line 5 |
| 핀 7 | P6 — Quasi-bidirectional I/O port line 6 |
| 핀 8 | P7 — Quasi-bidirectional I/O port line 7 |
| 핀 9 | SCL — I2C serial clock input |
| 핀 10 | SDA — I2C serial data input and output |
| 핀 11 | INT — Interrupt output |
| 핀 12 | GND — Ground reference |
| 핀 13 | A0 — I2C address input 0 |
| 핀 14 | A1 — I2C address input 1 |
| 핀 15 | A2 — I2C address input 2 |
| 핀 16 | VCC — Power supply input |
일반적인 애플리케이션
PCF8574NG4 적합 용도: 6 애플리케이션s: Industrial Control Panels, Relay and Solenoid Control, Keypad and Switch Sensing, LED and Indicator Interfaces, Remote Sensor Input Collection, Embedded Instrumentation Interfaces.
Industrial Control Panels
The PCF8574NG4 is well suited to industrial control panels that need more switch inputs and indicator outputs than the host controller can provide directly. Its eight quasi-bidirectional lines can monitor panel selectors and operate compatible indicators or control inputs through the I2C bus. The specified 2.5 V to 6 V VCC range supports 3.3 V and 5 V control electronics, while the 100 kHz bus limit suits slow-changing panel signals. Designers should account for the port's asymmetrical sink and source capabilities and protect external connectors against industrial transients.
추천
Relay and Solenoid Control
A PCF8574NG4 can provide a compact remote output port for relays, solenoids, and latching control loads when the attached circuits remain within the electrical limits of the quasi-bidirectional drivers. The host writes the desired output pattern over the 100 kHz I2C interface rather than consuming one GPIO pin per load. Because the port is primarily intended to sink current, relay-driver selection and flyback protection are critical. The 16-pin PDIP format also suits repairable, through-hole control boards where a socketed implementation is preferred.
추천
Keypad and Switch Sensing
The PCF8574NG4 can consolidate switch or keypad scanning into eight remote port inputs while retaining a single two-wire I2C connection to the controller. With a 100 kHz maximum bus frequency, it is appropriate for human-operated inputs whose switching rates are modest compared with high-speed digital buses. Its interrupt output can indicate a changed input state so the host can read the port when needed. Firmware must account for I2C address selection, debounce timing, and the electrical behavior of the quasi-bidirectional input stage.
추천
LED and Indicator Interfaces
The PCF8574NG4 can drive compatible LED indicators, status flags, or low-current display-control lines through a compact I2C-controlled port. Grouping indicators on an expander preserves microcontroller GPIO capacity for higher-bandwidth tasks and allows firmware to update several outputs with one serial transaction. Because quasi-bidirectional outputs are optimized for sinking current, the LED direction and current-limiting arrangement should be selected to match the port characteristics. The 2.5 V to 6 V operating range also permits the same expander to serve 3.3 V and 5 V indicator systems.
추천
Remote Sensor Input Collection
The PCF8574NG4 can collect several digital sensor or alarm signals in a remote enclosure and report their state to a controller over I2C. This arrangement limits cable conductors to clock, data, ground, and supply while allowing the eight port inputs to interface with compatible switches, limit detectors, or digital sensors. The 100 kHz bus rate provides adequate throughput for slowly changing discrete signals. Input thresholds, leakage behavior, address assignment, and any protection network must be checked against the voltage levels used by the remote equipment.
추천
Embedded Instrumentation Interfaces
The PCF8574NG4 can extend a measurement or laboratory instrument with control and status lines without requiring a large microcontroller package. Digital range-select switches, relay commands, front-panel status inputs, and alarm outputs are typical loads for its eight quasi-bidirectional lines. Its 16-pin PDIP package is particularly convenient for through-hole prototypes, educational instruments, and repairable legacy-style boards. Firmware should establish the I2C address before other devices respond, and the interrupt path should be configured to avoid false triggers from transient mechanical contacts.
추천
추천 제품 요약
엔지니어링 참조 데이터: PCF8574NG4 — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | PCF8574N | PCF8574P,112 | PCF8574AN | PCF8574AP,112 | PCF8574ANG4 |
|---|---|---|---|---|---|---|
| Package | 16-DIP (0.300 inch, 7.62 mm) | 16-DIP (0.300 inch, 7.62 mm) | 16-DIP (0.300 inch, 7.62 mm) | 16-DIP (0.300 inch, 7.62 mm) | 16-DIP (0.300 inch, 7.62 mm) | 16-DIP (0.300 inch, 7.62 mm) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Number of I/O Lines | 8 | 8 | 8 | 8 | 8 | 8 |
| I2C Bus Frequency | 100 kHz | 100 kHz | 100 kHz | 100 kHz | 100 kHz | 100 kHz |
| Port Type | 8-bit quasi-bidirectional | 8-bit quasi-bidirectional | 8-bit quasi-bidirectional | 8-bit quasi-bidirectional | 8-bit quasi-bidirectional | 8-bit quasi-bidirectional |
| Interrupt Function | Yes | Yes | Yes | Yes | Yes | Yes |
주요 차별점
- Direct through-hole expansion with eight I/O lines (vs PCA9554PWR)
- Standard-mode I2C performance (vs PCF8574AN)
- Legacy-friendly 7.62 mm lead pitch (vs PCF8574AP,112)
설계 노트
The PCF8574NG4 operates across a 2.5 V to 6 V VCC range, but its I2C pins must remain compatible with the voltage used by the bus pull-ups. Do not automatically pull SDA and SCL to VCC if another device on the bus uses a lower logic level. Confirm the input and open-drain output voltage limits for every participant, and choose pull-up values from the bus capacitance and 100 kHz operating requirement in the manufacturer datasheet.
Place the expander close to the connectors or remote signals it serves to keep I2C wiring short and avoid routing vulnerable external signals through a crowded logic area. Route SDA and SCL away from relay contacts, switching-power nodes, and other sources of electrical noise. Provide solid ground return paths, decouple VCC near the device according to the manufacturer guidance, and maintain clearance appropriate to the assembly's voltage and environmental requirements.
Do not assume that an output written as logic high behaves like a fully push-pull GPIO. The PCF8574 uses quasi-bidirectional ports, so driver source and sink behavior must be checked before driving LEDs or other loads. Also assign each device a unique I2C address, account for power-up states in firmware, and use pull-ups or another defined strategy so SDA and SCL cannot remain in an indeterminate state.
규정 준수 정보
The listed component is a Texas Instruments 16-DIP I/O expander, but no explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declaration was identified for the exact orderable part.
