PCA9501PW - 8-Bit I/O Expander with 2-kbit EEPROM | NXP
部品番号: PCA9501PW ✓ 生産中PCA9501PW 概要
An I/O expander is an interface IC that increases the number of digital input and output pins available to a host microcontroller or embedded processor. The PCA9501 sits within the interface IC hierarchy, where it connects a serial I2C or SMBus controller to LEDs, switches, sensors, and other board-level logic. Its quasi-bidirectional outputs can read external logic states while also driving indicator and control devices.
The PCA9501 provides eight GPIO ports, a 2-kbit on-board EEPROM, an interrupt output, and six hardware address inputs. The EEPROM provides nonvolatile storage alongside the GPIO function, allowing the bus master to retain configuration or identification data. Hardware address pins allow up to 64 PCA9501 devices to coexist on one bus when address assignments and bus loading permit.
The I2C and SMBus interfaces support operation at frequencies up to 400 kHz. Each GPIO may be configured independently as an input or output, and the input data and output configuration registers follow the familiar programming model of the PCF8574 family. The interrupt pin provides a hardware indication that one or more inputs have changed, reducing the need for continuous polling.
Typical uses include LED and relay-control interfaces, configuration and status I/O, telecommunications equipment, networking hardware, base-station systems, and general-purpose expansion for installed boards. The integrated EEPROM also makes the device useful where a small amount of nonvolatile board data must accompany the I/O functions.
Designers should account for the electrical behavior of quasi-bidirectional ports, pull up I2C and open-drain interrupt lines as required, and verify logic thresholds before driving external loads. PCB layouts should route the bus cleanly, provide stable bypass capacitance near the supply pins, and maintain adequate spacing between the TSSOP body and adjacent copper features.
This page combines the verified NXP product information, manufacturer datasheet, distributor listing, and cross-reference results with practical guidance on pin behavior, bus addressing, interrupt handling, EEPROM use, PCB layout, and drop-in replacement assessment.
ドロップイン代替品: PCA9501PW — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。
PCA9564PW
✅ ドロップイン📋 参考代替品（カタログ未掲載）
PCA9501PW 仕様
| Device Type | 8-bit I/O expander with integrated EEPROM |
| Number of I/O Pins | 8 pins |
| GPIO Configuration | Independently configurable as inputs or outputs |
| GPIO Logic Type | Quasi-bidirectional |
| Integrated EEPROM Capacity | 2 kbit |
| Host Interface | I2C and SMBus |
| Maximum Bus Frequency | 400 kHz |
| 動作電源電圧 | 2.5 V to 3.6 V |
| Hardware Address Inputs | 6 pins |
| Maximum Device Count on Bus | 64 devices |
| Interrupt Feature | 1 interrupt output |
| パッケージ | TSSOP-20 |
| 実装タイプ | Surface mount |
| 動作温度範囲 | -40 °C to +85 °C |
| ライフサイクル状態 | Active |
| PCF8574 Compatibility | Configuration-writing method follows PCF8574 |
| Bus Device Separation | GPIO and EEPROM appear as separate devices to the bus master |
PCA9501PW tssop-20 ピン配置ガイド
PCA9501PW (tssop-20 パッケージ) のピン配置。 ピン番号、機能、接続図はメーカーのデータシートで定義されています。正確なフットプリントとはんだ付けのガイドラインについては、データシートを参照してください。
詳細なピン配置データはありません: PCA9501PW.
詳細は データシート をご参照ください。
主な用途
PCA9501PW の用途: 6 件s: LED and Indicator Control, Industrial Status Monitoring, Telecommunications Equipment Control, General-Purpose Embedded GPIO Expansion, Configuration Memory for Installed Cards, Network Equipment Front Panels.
LED and Indicator Control
The PCA9501PW fits LED and indicator-control boards because it provides 8 independently configurable quasi-bidirectional ports while communicating with the host over I2C or SMBus at up to 400 kHz. A controller can update several indicators through one serial interface instead of allocating a separate GPIO pin to every LED. According to the NXP manufacturer datasheet, the ports are suitable for activating indicator devices, but the designer must verify each LED’s forward current, polarity, series resistance, and the available port drive capability against the electrical characteristics. For shared indicators, software can read the port-state register and preserve configuration changes in the integrated 2-kbit EEPROM, reducing repeated host-side setup after reset.
おすすめ
Industrial Status Monitoring
The PCA9501PW is appropriate for industrial status monitoring because its 8 quasi-bidirectional ports can sample board-level logic states and report changes through the interrupt output. This allows a supervisory controller to receive an event-driven indication instead of polling every status line continuously. The verified NXP datasheet supports operation from 2.5 V to 3.6 V and an I2C/SMBus rate up to 400 kHz, enabling connection to 3.3 V embedded systems. Engineers should confirm the input thresholds, polarity, pull-up requirements, and isolation strategy for factory signals before connecting external equipment.
おすすめ
Telecommunications Equipment Control
The PCA9501PW suits telecommunications and networking equipment that needs additional control and status lines without expanding the host processor’s pin count. Its 8 GPIO ports can monitor board conditions or operate peripheral indicators, while six address inputs support bus identification. According to the NXP datasheet, as many as 64 PCA9501 devices can be addressed when the bus design permits, making the part useful in multi-card telecom systems. The 400 kHz serial interface also helps reduce control traffic, although designers must account for EEPROM access time and overall bus loading when polling multiple devices.
おすすめ
General-Purpose Embedded GPIO Expansion
The PCA9501PW provides a straightforward way to add 8 GPIO lines to an embedded controller through I2C or SMBus. The ports can be independently assigned as inputs or outputs, and the configuration-writing method follows the PCF8574 approach described by NXP. Because the device also contains a 2-kbit EEPROM, a host can retain board configuration, calibration identifiers, or serial-number data alongside general I/O. The 400 kHz bus limit supports efficient updates, but firmware should include timeout handling and account for the additional propagation time associated with repeated serial transactions.
おすすめ
Configuration Memory for Installed Cards
The PCA9501PW is useful in installed-card and field-service equipment where a small amount of nonvolatile data must travel with the board’s I/O interface. The integrated 2-kbit EEPROM can retain configuration or identification information, while the 8 GPIO ports handle external status and control functions. According to the NXP manufacturer datasheet, the EEPROM appears as a separate device to the bus master even though both functions share one package and address space. Firmware should include write-cycle handling, data validation, and a mechanism for recovering from interrupted writes so that configuration information remains reliable.
おすすめ
Network Equipment Front Panels
The PCA9501PW can support front-panel status and indicator functions in networking equipment by concentrating several LED and status inputs behind an I2C or SMBus connection. Eight quasi-bidirectional ports can be reconfigured as system conditions change, while the interrupt output lets the main controller react to relevant input transitions. The verified specifications establish a 2.5 V to 3.6 V supply range and a maximum bus frequency of 400 kHz. Layout and firmware planning should account for LED current, bus pull-up placement, debounce requirements, and whether a changed port state should trigger an immediate interrupt.
おすすめ
おすすめ製品の概要
エンジニアリング参考データ: PCA9501PW — 比較、設計ガイダンス、コンプライアンス情報。
選定ガイド
代替品との比較
| パラメータ | この製品 | PCA9564PW |
|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors |
| Package | TSSOP-20 | TSSOP-20 - same |
| I/O Port Count | 8 | 8 |
| Integrated EEPROM | 2 kbit | 2 kbit |
| Serial Interface | I2C and SMBus | I2C and SMBus |
| Address Inputs | 6 | 6 |
| Interrupt Output | Yes | Yes |
| Lifecycle Status | Active | Active |
主な差別化要因
- Combines general-purpose GPIO expansion with nonvolatile storage （vs PCF8574PW)
- Provides an explicit interrupt path （vs PCA9564PW)
- Supports a practical 3.3 V operating range （vs PCA9564PW)
設計ノート
Route the I2C bus with short, continuous traces and place pull-up resistors at the physically correct bus location rather than scattering them across the board. Keep the PCA9501PW address-input connections away from high-current switching paths so that address programming remains stable during startup. Although the device supports up to 400 kHz, the achievable rate depends on bus capacitance, pull-up resistance, clock stretching behavior, and the complete system topology.
Provide a stable 2.5 V to 3.6 V supply and place the required bypass capacitor close to the device's supply and ground connections. Check the actual output current drawn by the quasi-bidirectional ports against the manufacturer's electrical limits rather than treating every GPIO as a full-strength push-pull output. For LED or relay loads, verify that external drivers, resistors, and polarity protection prevent excessive port current or back-powering an unpowered device.
Do not assume that a similarly packaged I/O expander is a direct replacement. Although PCA9564PW shares the TSSOP-20 format and major functional characteristics, compare the complete NXP register maps, address behavior, power-on defaults, interrupt polarity, electrical limits, and timing characteristics before substitution. Also verify the package pin mapping from the manufacturer drawings rather than relying on a distributor comparison page.
Use the interrupt output as an event-driven indication of input changes and configure the host to service the appropriate device address before returning to normal operation. Include software debouncing for external switches or slow-changing signals so that mechanical bounce does not create repeated interrupt servicing. Since the GPIO ports are quasi-bidirectional, avoid driving them externally while they are configured as outputs to prevent contention and ensure deterministic logic levels.
コンプライアンス情報
The supplied verified excerpts confirm an active lifecycle status but do not provide explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statements. No compliance claim has been inferred.
