PCA9534ADB - 8-Bit I2C I/O Expander, 16-SSOP | Texas Instruments
MPN: PCA9534ADB ✓ ActivePCA9534ADB Overview
An I/O expander is a bus-interface IC that increases the number of general-purpose input or output pins available to a host controller. The PCA9534ADB belongs to the I/O expander hierarchy within interface ICs and power management semiconductor systems. Its I2C or SMBus interface connects to a microcontroller, while the eight external pins can read logic states or control external circuits without adding another parallel GPIO port to the host board.
The principal features include eight configurable I/O pins, a 2.3 V to 5.5 V operating range, 400 kHz I2C operation, an interrupt output, and configuration registers. Three address pins select one of eight fixed device addresses on the shared bus. The manufacturer specifies a -40 °C to 85 °C operating-temperature range for the PCA9534ADB ordering code.
Communication with the device is register oriented. The host writes to the configuration register to select each port as input or output, reads the input and output registers to determine pin states, and uses the interrupt output to signal a change at a configured input pin. Separate input and output register behavior supports read-modify-write operations while allowing output-pin states to remain controlled independently from sensed input levels.
Typical applications include industrial control modules, sensor-hub boards, programmable logic controllers, instrument panels, and compact embedded products that need additional GPIO. Eight low-voltage digital lines can monitor switches, enable converters, control indicators, or read discrete sensors. The interrupt line reduces unnecessary bus polling when an external state change occurs, which is useful in battery- and power-conscious systems.
PCB design should route the I2C bus with short, compact traces and provide the decoupling and pull-up arrangements specified by the manufacturer. Confirm that the selected I/O direction, address configuration, and interrupt polarity match the firmware before release. Because the SSOP package has closely spaced leads, inspect solder-joint quality and confirm connector clearances during assembly.
This product page combines manufacturer specifications, bus and register guidance, package information, application-oriented design notes, and a qualification-focused comparison with available same-footprint alternatives. It is intended to help engineers determine whether the PCA9534ADB satisfies voltage, temperature, bus-speed, package, interrupt, and software requirements before schematic capture or PCB layout.
Drop-in alternatives for PCA9534ADB — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with PCA9534ADB (same form factor and footprint) — differing in Configuration Registers, Interrupt Output, Package.
PCA9554DB
✅ Drop-InContact for price
View Datasheet →TCA9554ADBR
✅ Drop-In📋 Reference alternative (not in catalog)
PCA9534ADB Specifications
| Device Type | 8-bit I2C/SMBus low-power I/O expander |
| Number of I/O Pins | 8 |
| Supply Voltage Range | 2.3 V to 5.5 V |
| I2C Bus Speed | 400 kHz |
| Interface Support | I2C and SMBus |
| Interrupt Output | Yes |
| Configuration Registers | Yes |
| Hardware Address Inputs | 3 |
| Maximum Devices per Shared Bus | 8 |
| Package | 16-pin SSOP (DB) |
| Package Width | 5.30 mm |
| Operating Temperature Range | -40 °C to 85 °C |
| Mounting Type | Surface mount |
PCA9534ADB Pin Configuration
| Pin 1 | A0 — Address input A0 |
| Pin 2 | A1 — Address input A1 |
| Pin 3 | A2 — Address input A2 |
| Pin 4 | SCL — Serial clock input |
| Pin 5 | SDA — Serial data input and output |
| Pin 6 | P0 — Configurable I/O port 0 |
| Pin 7 | P1 — Configurable I/O port 1 |
| Pin 8 | P2 — Configurable I/O port 2 |
| Pin 9 | P3 — Configurable I/O port 3 |
| Pin 10 | INT — Interrupt output |
| Pin 11 | VDD — Power supply |
| Pin 12 | P4 — Configurable I/O port 4 |
| Pin 13 | P5 — Configurable I/O port 5 |
| Pin 14 | P6 — Configurable I/O port 6 |
| Pin 15 | P7 — Configurable I/O port 7 |
| Pin 16 | GND — Ground |
Typical Applications
PCA9534ADB is suitable for 6 applications: Industrial Control and Sensor I/O, Programmable Logic Controller Interface, Sensor Hub and Discrete Sensing, Instrument Panel and Human-Machine Interface, LED and Discrete System Control, Battery-Powered Embedded Module.
Industrial Control and Sensor I/O
The PCA9534ADB is suitable for industrial controller boards that need additional discrete inputs and outputs without expanding the host MCU package. Its eight configurable pins can monitor switches, read sensor-enable or fault signals, and control discrete loads while the I2C interface reduces host pin usage. Three address inputs support up to eight devices on one bus, and the interrupt output can alert the controller to a change at a monitored input. The 2.3 V to 5.5 V supply range accommodates common industrial logic levels, although every connected interface must meet the device's electrical limits.
Recommended
Programmable Logic Controller Interface
A PLC or compact embedded controller can use the PCA9534ADB to add eight low-voltage digital points to a bus-oriented design. Inputs can represent limit switches, interlocks, and status contacts, while outputs can drive enable inputs, indicators, or control signals to other modules. The configuration register provides a straightforward way to mix input and output directions. Hardware address selection allows several expanders to coexist, and the interrupt output supports event-driven handling instead of continuous polling. Firmware must configure the port directions and interpret the device's input and output registers correctly.
Recommended
Sensor Hub and Discrete Sensing
The PCA9534ADB can concentrate low-speed digital sensing around a sensor hub. Its eight ports may read presence, threshold, tamper, or alarm contacts and may control sensor enables, test modes, or communication-gated devices. The interrupt output is particularly useful when the controller should react to a changed input rather than repeatedly read the bus. Up to 400 kHz I2C speed provides sufficient bandwidth for typical status and control traffic. Designers should treat the pins as digital I/O rather than high-current or analog sensor interfaces, and should confirm pull-up and signal-level requirements in the manufacturer documentation.
Recommended
Instrument Panel and Human-Machine Interface
The PCA9534ADB is useful in compact instrument panels where the primary controller needs to read switches and update discrete panel indicators. Input ports can capture pushbuttons, selector positions, and door or alarm contacts, while output ports can drive LEDs, relay-enable signals, or display-control lines. The fixed address selection makes it possible to organize several panel sections logically on one bus. The interrupt output can wake or notify the controller after a user action. Because the I/O voltage and current limits are specific to the device, designers should use appropriate drivers for loads beyond the direct output capability.
Recommended
LED and Discrete System Control
The PCA9534ADB can control eight low-voltage digital destinations such as status LEDs, isolated digital switches, or enable inputs to other converters. Outputs may be individually configured through the device's registers, enabling firmware to change indicator states without adding dedicated driver pins to the host MCU. The interrupt feature is less central for output-only designs but remains available for mixed input and output ports. Use suitable current-limiting and drive circuitry for LED strings or loads that exceed the device's direct drive capability, and account for the voltage drop between the system supply and each output state.
Recommended
Battery-Powered Embedded Module
The PCA9534ADB is appropriate for compact battery-powered modules that need remote digital I/O but must minimize bus traffic. Eight ports add control and sensing capability without occupying eight host-controller GPIO pins, and the interrupt output can reduce repeated status reads when the system sleeps between events. The device's stated 2.3 V to 5.5 V operating range permits use across multiple common low-voltage platforms. Overall battery life still depends on the complete system because the host, pull-ups, LEDs, and connected loads can dominate consumption. Review the manufacturer's low-power characteristics before fixing the power budget.
Recommended
Recommended Products Summary
Engineering reference data for PCA9534ADB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PCA9554DB | TCA9554ADBR |
|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 16-SSOP (DB) | 16-SSOP (DB) | 16-SSOP (DB) |
| I/O Count | 8 bits | 8 bits | 8 bits |
| Interrupt Output | Yes | Yes | Yes |
| Configuration Registers | Yes | Yes | Yes |
Key Differentiators
- Lower inherent output holding power through the absence of internal I/O pull-ups (vs PCA9554DB)
- Native support for both I2C and SMBus (vs TCA9554ADBR)
- Eight selectable fixed addresses for multi-expander buses (vs PCA9554DB)
Design Notes
Place the decoupling capacitor close to VDD and GND, and route the I2C traces away from switching nodes and high-current return paths. Use address-selection resistors or straps for A0, A1, and A2 before power-up. Confirm the physical SSOP footprint dimensions, exposed or non-exposed pad status, copper clearance, and solder-assembly requirements against the manufacturer package drawing rather than inferring them from the family name.
The PCA9534ADB operates from 2.3 V to 5.5 V, but the complete interface must remain compatible with that range. Select I2C pull-ups for the actual bus voltage and total bus capacitance rather than applying one resistance value to every design. Confirm that external pull-ups do not exceed the device's sink-current rating, and review output-high and output-low levels against the host controller's input thresholds.
Do not treat a register-compatible-looking expander as an automatic software replacement. Validate the configuration-register bits, input versus output register semantics, reset values, address assignment, interrupt polarity, and write sequence for each candidate. PCA9534A removes the internal I/O pull-up resistors found on PCA9554-type devices, so moving from PCA9554DB to PCA9534ADB can change inactive-pin behavior and external pull-up requirements.
Keep SCL and SDA traces short, route them as a matched communication pair where practical, and minimize stubs from test pads or connectors. The manufacturer identifies 400 kHz as the maximum I2C rate for this device, but slower operation may be preferable in electrically long or noisy systems. Verify rise time, bus capacitance, pull-up strength, and contention at the interrupt line in the final board configuration.
Compliance Information
No explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statement was included in the cited product listings. Confirm current compliance documentation with the manufacturer for the exact ordering code.
