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HomeProductsIntegrated Circuits (ICs)Interface - I/O ExpandersPCA9555DBR
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PCA9555DBR - Texas Instruments

Manufacturer Part Number
PCA9555DBR
Manufacturer
Texas Instruments
Allelco Part Number
32D-PCA9555DBR
Warranty
1 Year Allelco Warranty - Find out more
Stock Status:
41,451 pcs available, New & Original
Parts Description
IC XPNDR 400KHZ I2C SMBUS 24SSOP
Package
24-SSOP
Data sheet
PCA9555DBR.pdf

PCN Assembly/Origin

Mult Dev A/T Site 16/Mar/2021.pdf

HTML Datasheet

PCA9555.pdf
RoHs Status
ROHS3 Compliant
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Our certification
In stock: 41451
  • Unit Price: $0.977
  • Subtotal: $0.00

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Quantity Unit Price Ext. Price
1+ $0.977 $0.98
10+ $0.821 $8.21
30+ $0.735 $22.05
100+ $0.639 $63.90
500+ $0.595 $297.50
1000+ $0.576 $576.00
The above prices does not include taxes and freight rates, which will be calculated on the order pages.

Specifications

PCA9555DBR Tech Specifications
Texas Instruments - PCA9555DBR technical specifications, attributes, parameters and parts with similar specifications to Texas Instruments - PCA9555DBR

Product Attribute Attribute Value
Manufacturer Texas Instruments
Voltage - Supply 2.3V ~ 5.5V
Supplier Device Package 24-SSOP
Series -
Package / Case 24-SSOP (0.209", 5.30mm Width)
Package Tape & Reel (TR)
Output Type Push-Pull
Operating Temperature -40°C ~ 85°C
Product Attribute Attribute Value
Number of I/O 16
Mounting Type Surface Mount
Interrupt Output Yes
Interface I²C, SMBus
Features POR
Current - Output Source/Sink 10mA, 25mA
Clock Frequency 400 kHz
Base Product Number PCA9555

Environmental & Export Classifications

ATTRIBUTE DESCRIPTION
RoHs Status ROHS3 Compliant
Moisture Sensitivity Level (MSL) 1 (Unlimited)
REACH Status REACH Unaffected
ECCN EAR99
HTSUS 8542.39.0001

Parts Introduction

PCA9555DBR Image
PCA9555DBR (1)

Manufacturer Part Number

PCA9555DBR

Manufacturer

Texas Instruments

Introduction

The PCA9555DBR from Texas Instruments is a 16-bit I/O expander with an I2C and SMBus interface, designed for versatile interfacing in microcontroller-based systems.

Product Features and Performance

16 I/O ports

I2C and SMBus compatible interface

Interrupt output feature

Push-Pull output type

Power-on reset

Supports up to 400 kHz clock frequency

Product Advantages

High compatibility with various microcontroller systems

Enhanced data handling capacity with 16-bit extension

Low power consumption

Integrated interrupt output to manage input change notifications

Key Technical Parameters

Number of I/O: 16

Interface: I2C, SMBus

Output Type: Push-Pull

Current - Output Source/Sink: 10 mA, 25 mA

Clock Frequency: 400 kHz

Voltage - Supply: 2.3V to 5.5V

Operating Temperature: -40°C to 85°C

Quality and Safety Features

Built with robust surface mount technology

Designed to operate under a wide range of environmental conditions

Compatibility

Compatible with devices that support I2C and SMBus protocols

Application Areas

Industrial automation

Consumer electronics

Data servers

Communication systems

Product Lifecycle

Status: Active

Not nearing discontinuation

Replacements or upgrades readily available

Several Key Reasons to Choose This Product

Flexible supply voltage range from 2.3V to 5.5V to suit various system designs

Highly responsive with up to 400 kHz clock frequency ensuring swift data transfer

Power-on reset feature enhances system reliability after power interruptions

Capable of sourcing or sinking current up to 25 mA for driving connected components

Wide operating temperature makes it suitable for harsh environments

Frequently Asked Questions(FAQ)

How does the PCA9555DBR handle input debouncing in real-world I/O expander applications, and what design considerations are necessary to ensure reliable digital signal capture?
The PCA9555DBR supports configurable input filtering through its internal input port status register polling mechanism, but it does not include dedicated hardware debouncing circuitry. Engineers must implement software-based debouncing by reading the input states at intervals shorter than the expected bounce duration—typically 1–2 ms for mechanical switches. Given the 400 kHz I²C clock, the maximum response latency per byte is approximately 30 µs, which allows for responsive sampling. However, designers should account for this overhead when timing-critical applications require immediate interrupt responses. Proper PCB layout and use of pull-up/pull-down resistors further mitigate erratic behavior during switching events.
What are the key differences between using the PCA9555DBR with a 2.3V versus 5.5V supply voltage in terms of noise margin and compatibility with downstream logic families?
Operating the PCA9555DBR at 2.3V reduces power consumption and improves battery life in low-voltage systems but decreases noise margin compared to 5.5V operation. At 2.3V, the high-level output voltage (VOH) drops closer to the minimum threshold required for reliable recognition by 3.3V or 5V CMOS inputs, potentially increasing susceptibility to noise-induced errors. In contrast, a 5.5V supply provides higher VOH margins, enhancing robustness in environments with electrical interference. Designers interfacing with mixed-voltage systems should verify that all connected devices meet the PCA9555DBR’s VIH specification under the lowest expected supply condition to maintain signal integrity.
Can the PCA9555DBR safely drive inductive loads such as relays or solenoids directly from its GPIO pins, and what protection components are recommended?
No, the PCA9555DBR is not rated for direct driving of inductive loads due to its limited current sourcing/sinking capability of 10mA/25mA and lack of built-in flyback protection. Inductive kickback from relays or solenoids can damage the IC if back-EMF exceeds the absolute maximum ratings. To safely control such loads, an external driver stage—such as a MOSFET or optocoupled transistor array—must be used. A freewheeling diode across the load or a TVS diode at the output pin is strongly advised to clamp transient voltages below 6V (absolute max VCC) and within safe operating limits.
How does the interrupt feature of the PCA9555DBR function when monitoring multiple GPIO lines, and what is the worst-case latency before the host detects a change?
The PCA9555DBR generates a single interrupt signal (INT) upon any change on its 16 GPIO pins, regardless of direction or location. When enabled via the configuration registers, the INT pin asserts low until the host reads the input port register, clearing the interrupt condition. Worst-case interrupt latency depends on I²C transaction timing: at 400 kHz, writing the read command takes about 2.5 µs, followed by up to 8 bytes × 9 bits = 72 bits × 2.5 µs/bit ≈ 180 µs total transfer time. Thus, end-to-end latency from pin transition to host awareness is typically under 200 µs, suitable for most non-real-time control loops but insufficient for hard real-time applications without polling fallbacks.
What trade-offs exist between using the PCA9555DBR in open-drain versus push-pull output mode when driving LED indicators or simple digital loads?
Push-pull mode enables full-swing output (near VCC or GND), providing faster rise/fall times and higher current drive (up to 25mA sink), ideal for directly lighting LEDs with appropriate series resistors. Open-drain mode requires an external pull-up resistor and limits output voltage to VCC, making it better suited for level-shifting or bus sharing. While push-pull offers superior noise immunity and speed, open-drain simplifies bidirectional communication on shared lines. For the PCA9555DBR, choosing push-pull maximizes performance for point-to-point loads; open-drain adds flexibility at the cost of increased component count and potential RC delays in high-capacitance environments.
How does the PCA9555DBR compare to alternative I/O expanders like the MCP23017 in handling simultaneous multi-pin transitions during system initialization?
Unlike the PCA9555DBR, which triggers a global interrupt on any pin change, the MCP23017 supports per-pin interrupt enable masking, allowing finer-grained event tracking. This makes the MCP23017 more efficient in systems where only specific inputs matter. Conversely, the PCA9555DBR’s simpler interrupt model reduces firmware complexity but may generate spurious interrupts during bulk state changes—common during power-up when multiple signals stabilize asynchronously. Both support 400 kHz I²C and similar voltage ranges, but the PCA9555DBR integrates power-on reset circuitry natively, reducing boot-time initialization code burden compared to the MCP23017, which requires external POR supervision for reliable startup sequencing.
Is it possible to cascade two PCA9555DBR devices on the same I²C bus without address conflicts, and how would one configure their unique addressing?
Yes, cascading is feasible by leveraging the PCA9555DBR’s three hardware address pins (A0, A1, A2). Each device can be assigned a unique combination of these pins tied to either VCC or GND, yielding up to eight distinct addresses (0x20–0x27). For example, connecting A0=1, A1=0, A2=0 sets the address to 0x22, while A0=0, A1=1, A2=1 yields 0x25. Care must be taken to avoid duplicate configurations during board bring-up. Additionally, pull-up resistors on SDA/SCL must be sized to accommodate the combined capacitance of both devices plus trace length, ensuring rise times stay within I²C spec (<300 ns for standard mode).
What impact do supply rail transients have on the PCA9555DBR’s internal logic, and how should decoupling be implemented for stable operation?
Although the PCA9555DBR operates over a wide 2.3V–5.5V range, sudden voltage spikes above 5.5V or dips below 2.0V can corrupt internal state or damage the device. Transients common in industrial environments may exceed this tolerance. Therefore, a 0.1 µF ceramic capacitor placed within 5 mm of the VCC and GND pins is essential. For systems with long power traces or noisy sources, adding a 10 µF tantalum or electrolytic capacitor near the board’s power entry point improves transient response. The MSL 1 rating indicates unlimited shelf life, but proper storage and handling remain critical to prevent moisture-induced delamination during soldering.
Can the PCA9555DBR be used in automotive-grade applications requiring functional safety certification, and what limitations apply?
The PCA9555DBR is not qualified to automotive standards (e.g., AEC-Q100) and lacks diagnostic features such as built-in self-test or fault reporting required for ASIL-rated designs. Its commercial-grade temperature range (-40°C to +85°C) covers many industrial uses but falls short of extended automotive requirements (-40°C to +125°C). Consequently, it is unsuitable for safety-critical functions in vehicles unless supplemented with external monitoring circuitry. Engineers considering automotive deployment must perform rigorous reliability testing, including thermal cycling, ESD hardening, and EMI compliance, to validate suitability beyond datasheet guarantees.
How does the PCA9555DBR’s clock stretching capability affect system timing budgets in master-controlled I²C networks?
As a slave device, the PCA9555DBR supports clock stretching by holding SCL low after receiving an acknowledgment bit, thereby delaying subsequent data phases. This feature ensures the master waits until the expander completes internal processing, preventing data loss. However, excessive stretching increases overall I²C bus utilization and can starve other slaves in multi-drop configurations. With a 400 kHz nominal frequency, each byte transfer includes 9 clock cycles; stretching beyond 50 µs per phase risks violating timing budgets in tight-loop applications. Designers should minimize software delays in expander firmware and avoid nested operations during active transfers to preserve bus efficiency.
What role does the Power-On Reset (POR) feature play in preventing glitches during system startup with the PCA9555DBR?
The integrated POR circuit ensures all internal registers initialize to known states upon power ramp-up, preventing undefined outputs or erratic interrupts during early boot. Without POR, GPIOs might briefly float or toggle unpredictably, causing false trigger events in downstream logic. The PCA9555DBR’s POR threshold is calibrated to ignore brief brownouts, yet sufficient rise time must still be maintained (>100 µs typical) to guarantee clean initialization. This eliminates the need for external reset controllers solely for the expander, simplifying BOM and reducing component count in space-constrained designs.
How does the choice between Cut Tape and Digi-Reel packaging affect procurement lead times and assembly processes for the PCA9555DBR?
Cut Tape (CT) packaging delivers individual reels of components ready for automated pick-and-place machines, offering faster turnaround for prototyping or small-batch production. Digi-Reel® provides larger reel quantities with standardized tape pitch, aligning with industry SMT lines and reducing placement setup time. Neither format affects electrical performance, but CT may incur higher unit costs and longer supplier lead times for low volumes. For high-volume manufacturing, Digi-Reel ensures consistency and traceability. Both comply with RoHS3 and MSL 1, so storage conditions remain identical regardless of packaging variant.

Parts with Similar Specifications

The three parts on the right have similar specifications to Texas Instruments PCA9555DBR

Product Attribute PCA9555DBQR PCA9555DBQRG4 PCA9555DB,112 PCA9555DWR
Part Number PCA9555DBQR PCA9555DBQRG4 PCA9555DB,112 PCA9555DWR
Manufacturer Texas Instruments Luminary Micro / Texas Instruments NXP USA Inc. Texas Instruments
Series - - - -
Features - - - Simultaneous Sampling
Package / Case - 196-LFBGA 16-DIP (0.300', 7.62mm) 64-VFQFN Exposed Pad
Mounting Type - Surface Mount Through Hole Surface Mount
Voltage - Supply - - - -
Output Type - Current - Unbuffered Voltage - Buffered -
Package - Tape & Reel (TR) Tube Tape & Reel (TR)
Interface - - - -
Supplier Device Package - 196-NFBGA (12x12) 16-PDIP 64-VQFN (9x9)
Current - Output Source/Sink - - - -
Number of I/O - - - -
Clock Frequency - - - -
Interrupt Output - - - -
Base Product Number - DAC34H84 MAX500 ADS62P42
Operating Temperature - -40°C ~ 85°C 0°C ~ 70°C -40°C ~ 85°C

PCA9555DBR Datasheet PDF

Download PCA9555DBR pdf datasheets and Texas Instruments documentation for PCA9555DBR - Texas Instruments.

PCN Design/Specification
Datasheet Update 25/Jun/2014.pdf PCA9555 04/Sep/2018.pdf
PCN Assembly/Origin
Mult Dev A/T Site 16/Mar/2021.pdf
HTML Datasheet
PCA9555.pdf

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Customer Reviews

Evaluation: 10 Articles

  • Nath***rooks
    Jun 11, 2026

    Installed this power component in a converter board. Output remained stable under different load conditions and thermal performance was better than expected.

  • Dani***alkerTech
    Jun 1, 2026

    Product works, but setup took more effort than expected. Once configured the MCU ran reliably, although documentation support felt older compared with newer platforms. Fine for maintenance projects.

  • Yuki***aka88
    May 26, 2026

    信号通信プロジェクトでこのRS-485トランシーバーを使用しました。設置は簡単で、長距離ケーブルでも通信は安定していました。消費電力も、以前使用していたものより低くなっています。

  • Stev***aker
    May 20, 2026

    Solid diode for power rectification. Works well in switching circuits.

  • Bran***Lewis
    May 11, 2026

    Compact FPGA with good performance. Suitable for basic signal processing tasks.

  • Oliv***arris
    May 7, 2026

    Reliable I/O expander. Works well in embedded control applications.

  • Jess***Jones
    Apr 17, 2026

    It offers good value for the price, and the specifications match the description. I’ve been using it for two days with no issues, and I’ll definitely buy it again if I need it in the future.

  • Mich***Smith
    Apr 17, 2026

    Shipping was on time, the component pins are neatly aligned, and I tested 10 of them with a multimeter—all readings were within the specified range. Highly recommended.

  • Aman***arris
    Apr 3, 2026

    It was great—the entire process, from placing the order to receiving the package, went very smoothly. The components were consistent, the price was fair, and I had a very pleasant shopping experience.

  • Mike***nch
    Apr 3, 2026

    Better than expected! The resistance and capacitance readings were spot-on, and it passed the test on the first try. The service was reliable, and the packaging was thoughtful—I highly recommend it.

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PCA9555DBR Image

PCA9555DBR

Texas Instruments
32D-PCA9555DBR

Want a better price? Add to Cart and Submit RFQ now, we'll contact you immediately.

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