PCA9554ADB - 8-Bit I2C GPIO Expander | NXP Semiconductors
Référence : PCA9554ADB ✗ Fin de viePCA9554ADB Présentation
An I/O expander is an interface IC that increases the number of general-purpose input/output pins available to a host controller. In the electronic-component hierarchy, the PCA9554ADB belongs to the I/O expander class, interface ICs, and ultimately semiconductor devices. It communicates with a microcontroller, application processor, or other system controller through the two-wire I2C bus or SMBus, reducing direct GPIO requirements without requiring a parallel peripheral bus.
The PCA9554A family provides eight independently configurable ports and an interrupt output. Three hardware address pins, A0, A1, and A2, can program the fixed I2C address and allow as many as eight devices to share one bus. Weak pull-ups are provided for the I2C interface, while configuration, input, output, and polarity-inversion registers make the ports suitable for both sensing and driving external signals.
The PCA9554A architecture also provides practical address flexibility for systems containing multiple expanders. The interrupt line allows the host to detect a change on a configured input without continuously polling the input register. Its 2.3 V to 5.5 V supply range supports both 3.3 V and 5 V systems, while the stated 400 kHz bus limit enables comparatively fast communication with the system controller.
Typical uses include adding keypad or switch inputs, monitoring discrete sensors, reading LED or relay status, and controlling auxiliary digital signals in embedded equipment. It is particularly useful when the host processor has too few GPIOs for peripheral control or when a modular board requires addressable digital I/O distributed across an I2C bus.
Designers should confirm the controller's logic levels, address assignment, pull-up requirements, and startup behavior in the manufacturer datasheet. Software compatibility must also be checked because the PCA9554A is pin-to-pin and I2C-address compatible with the PCF8574A, but its enhanced register architecture requires software changes.
This product page combines the verified manufacturer and distributor information for the PCA9554ADB with lifecycle context, replacement guidance, interface explanations, and design-oriented selection notes. Those additions help engineers distinguish hardware compatibility from firmware compatibility and identify whether an existing PCB can be reused during sourcing transitions.
Alternatives de remplacement direct pour PCA9554ADB — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec PCA9554ADB (même facteur de forme et même empreinte) — différant par Interrupt Output, Package.
PCA9554ABS3,118
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Voir la fiche technique →PCA9554ADB Spécifications
| Product Type | 8-bit I2C/SMBus I/O expander |
| Number of I/O Ports | 8 ports |
| Supply Voltage Range | 2.3 V to 5.5 V |
| I2C Bus Frequency | 400 kHz maximum |
| Interface | I2C and SMBus |
| Interrupt Output | Yes |
| Configuration Register | Yes |
| Polarity Inversion Register | Yes |
| Input Port Register | Yes |
| Output Port Register | Yes |
| Address Selection Pins | 3 pins: A0, A1, and A2 |
| Maximum Devices per Shared Bus | 8 devices |
| Boîtier | 16-pin SSOP |
| Type de montage | Surface mount |
| Plage de température de fonctionnement | -40 °C to +85 °C |
| Weak Pull-Up Feature | Yes |
| Statut du cycle de vie | End of life |
Guide de configuration des broches du PCA9554ADB 16-pin ssop
Configuration des broches du PCA9554ADB (boîtier 16-pin ssop). La numérotation des broches, les fonctions et les schémas de connexion sont définis dans la fiche technique du fabricant. Consultez-la pour l'empreinte exacte et les directives de soudage.
Aucune donnée de brochage détaillée disponible pour PCA9554ADB.
Consultez la fiche technique pour la configuration complète des broches.
Applications typiques
PCA9554ADB convient pour 6 applications: Industrial Control Panel I/O Expansion, Embedded Keypad and Switch Interface, Remote Sensor and Discrete Status Monitoring, LED and Relay Status Control, Communication and Network Equipment Control, Portable and Battery-Powered Embedded Devices.
Industrial Control Panel I/O Expansion
The PCA9554ADB fits an industrial control panel where a controller needs more digital connections than its native GPIO count can provide. Its eight ports can read pushbuttons and limit switches while driving status indicators, and the 2.3 V to 5.5 V operating range supports common 24 V-system interface electronics when appropriate isolation is added externally. The interrupt output can notify the controller of an input change, while A0, A1, and A2 permit multiple expanders on one I2C bus. Because the verified information does not include detailed port-drive ratings, relay drivers, isolation, or 24 V tolerances, the PCB should use qualified external interface circuits rather than assuming direct field-voltage compatibility.
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Embedded Keypad and Switch Interface
The PCA9554ADB is suitable for connecting a matrix-free keypad, selector switches, or configuration buttons over I2C. Eight ports provide dedicated sensing or control points, and the input, output, and polarity-inversion registers allow the firmware to represent active-low or active-high hardware consistently. The interrupt output can wake or prompt the host after a user action, avoiding continuous polling. Its 400 kHz maximum I2C rate supports rapid scan cycles, although actual scan timing also depends on bus loading and the host firmware. Verify debounce, input thresholds, and pull-up arrangements in the complete data sheet and schematic rather than relying only on the family-level verified specifications.
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Remote Sensor and Discrete Status Monitoring
The PCA9554ADB can collect digital status from sensors, interlocks, presence detectors, or other external equipment when those signals operate within the device's supported electrical environment. Eight inputs make the expander useful for compact monitoring nodes where an embedded controller has limited connector space. The interrupt output provides event-driven handling, and the polarity-inversion register simplifies active-low sensor outputs. As a practical limitation, the verified material does not specify input leakage, logic thresholds, debounce behavior, or isolation ratings. Engineers should therefore add appropriate signal conditioning, protection, and grounding where industrial transients or long cable runs are involved.
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LED and Relay Status Control
The PCA9554ADB can provide additional low-rate digital control lines for LEDs, relay modules, or latching enable inputs in embedded equipment. The output register allows firmware to update groups of ports through the I2C bus, while the input register can read back the visible state of outputs. The interrupt feature remains useful when external circuitry changes a monitored line. For relays or mains-connected equipment, however, the PCA9554ADB should not be assumed to drive the load directly: the verified excerpts provide no output-current ratings or inductive-load specifications. Use qualified driver transistors, flyback protection, isolation, and suitable logic levels around the expander.
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Communication and Network Equipment Control
The PCA9554ADB is useful in communication equipment that requires low-speed housekeeping functions such as module resets, status LEDs, fault inputs, or configuration switches. Its 2.3 V to 5.5 V range accommodates common equipment rails, while the 400 kHz I2C limit is adequate for supervisory signals rather than high-throughput data. The three address pins allow several monitoring or control sections to share one bus, and the interrupt line can report an urgent external event. System-level details such as input thresholds, output drive, reset behavior, and power sequencing must be confirmed from the manufacturer data sheet before the part is used in new network hardware, particularly because the device is marked end of life.
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Portable and Battery-Powered Embedded Devices
The PCA9554ADB can expand a compact embedded controller's available I/O in a portable device, meter, or battery-operated sensor node. Operating from 2.3 V to 5.5 V provides flexibility across common low-voltage systems, and the I2C interface avoids dedicating many connector pins or microcontroller GPIO resources. The verified excerpts do not provide standby current, active current, or shutdown behavior, so battery-life analysis requires the complete electrical characteristics from the manufacturer. Designers should also weigh the part's end-of-life status against the risk of long-term sourcing when a fully specified currently supported replacement is unavailable.
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Récapitulatif des produits recommandés
Données de référence d'ingénierie pour PCA9554ADB — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | PCA9554A |
|---|---|---|
| Brand | NXP Semiconductors | Texas Instruments |
| Package | 16-SSOP | 16-SSOP |
| Product Type | 8-bit I2C/SMBus I/O expander | 8-bit I2C/SMBus I/O expander |
| Number of I/O Ports | 8 ports | 8 ports |
| Supply Voltage Range | 2.3 V to 5.5 V | 2.3 V to 5.5 V |
| Maximum I2C Frequency | 400 kHz | 400 kHz |
| Interrupt Output | Yes | Yes |
| Address Configuration | A0, A1, and A2 pins; up to 8 devices | A0, A1, and A2 pins; up to 8 devices |
| Lifecycle Status | End of life | No longer in production |
Principaux différenciateurs
- Eight independently configurable ports with enhanced register support (vs PCF8574A)
- Scalable fixed-address bus configuration (vs PCF8574A)
- Interrupt-assisted event detection (vs PCA9554A)
Notes de conception
Treat PCF8574A as a hardware-compatible migration option rather than a firmware-identical replacement. The NXP product information explicitly states that PCA9554A is pin-to-pin and I2C-address compatible with the PCF8574A, but software changes are required because of the PCA9554A enhancements. Before replacing the device, audit the driver for configuration, input, output, polarity-inversion, interrupt-mask, and interrupt-clear operations rather than assuming that a successful I2C transaction proves register compatibility.
Assign A0, A1, and A2 deliberately so that every PCA9554A on the shared I2C bus has a unique address. The manufacturer states that these three pins permit up to eight devices to share an I2C or SMBus. Keep the address-strapping layout accessible if several hardware configurations are planned, and verify the selected logic states during reset or power-up. Also account for the manufacturer's complete address map and external bus pull-up guidance, neither of which is fully reproduced in the verified excerpts.
Do not assume that every legacy 5 V peripheral can be connected directly to a PCA9554ADB operating from a 3.3 V rail. The verified data confirms a 2.3 V to 5.5 V supply range, but it does not include the detailed input thresholds, output-drive ratings, leakage currents, or absolute-maximum limits. Review the manufacturer electrical tables and use level translation or suitable interface circuits where signal compatibility is not explicitly guaranteed.
Informations de conformité
The verified excerpts do not provide explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals declarations for this exact ordering code. The NXP page identifies the part as end of life, while the Texas Instruments PCA9554ADB listing states that the part is no longer in production.