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NXP Semiconductors PCA9549D,112
- Part No.:
- PCA9549D,112
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
PCA9549D,112.pdf
- Description:
- IC INTERFACE SPECIALIZED 24SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,975
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Product details
Overview
PCA9549D,112 from NXP Semiconductors is an octal I²C-bus-controlled TTL-compatible bus switch IC used for dynamic I²C signal routing in multi-master or multi-peripheral systems. It provides eight independent bidirectional A/B channel switches with 5 Ω typical ON-state resistance, 2.3 V to 5.5 V supply operation, active LOW reset, and supports up to 400 kHz Fast-mode I²C clock frequency - enabling selective isolation of downstream I²C segments in server management, industrial PLCs, and embedded sensor hubs.
For engineers reviewing the PCA9549D,112 datasheet, PCA9549D,112 pinout, PCA9549D,112 application, or PCA9549D,112 equivalent, this page delivers verified functional specifications, SO24 package layout, real-world I²C multiplexing use cases, and validated alternative parts - all grounded in the official NXP PCA9549 Rev. 02 datasheet (2009) and ordering documentation.
Technical Context
The PCA9549D,112 implements Cross Bar Technology (CBT) switching logic controlled via a single-byte I²C write to its programmable control register (B7–B0), where each bit independently enables or disables one of eight A↔B channels. Its internal state machine resets on power-up or RESET assertion, initializing all bits to open (high-impedance).
It features hardware address inputs (A0–A2) supporting up to eight devices on one I²C bus, 5 V-tolerant I/O pins, and integrated input filtering on SCL/SDA to suppress noise spikes ≤50 ns. The device operates across 2.3–5.5 V, with Vo(sw) clamping behavior enabling voltage translation between mixed-voltage I²C domains (e.g., 5 V master ↔ 3.3 V peripherals).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Type | Octal bidirectional TTL-compatible bus switch (CBT architecture) |
| ON-State Resistance | 5 Ω typical at VDD = 5 V; ensures minimal signal attenuation and propagation delay (<0.25 ns) |
| I²C Interface | Fully compliant with SMBus standards; supports Standard-mode (100 kHz) and Fast-mode (400 kHz) |
| Supply Voltage Range | 2.3 V to 5.5 V - enables interoperability across 3.3 V and 5 V system domains |
| Reset Function | Active LOW RESET pin with 4 ns minimum pulse width; recovers I²C bus lockup by forcing all channels open |
| ESD Protection | 2000 V HBM, 200 V MM, 1000 V CDM - meets industrial-grade robustness requirements |
| Operating Temperature | −40 °C to +85 °C - qualified for extended industrial and telecom environments |
Pinout & Package
PCA9549D,112 is supplied in SO24 (SOT137-1) plastic small outline package: 24-pin, 7.5 mm body width, surface-mount, lead-free compatible.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1A–8A | Channel A-side inputs/outputs | Bidirectional I²C signal ports - connect to upstream master or shared bus segment |
| 1B–8B | Channel B-side inputs/outputs | Bidirectional I²C signal ports - connect to isolated downstream peripherals or slave banks |
| A0–A2 | Hardware address inputs | Set 3-bit slave address (1110 A2 A1 A0 R/W); allow up to eight PCA9549 devices on same bus |
| SCL / SDA | I²C serial clock/data lines | Control interface - accept standard I²C write/read commands to configure channel states |
| RESET | Active LOW reset input | Forces all channels open and clears I²C state machine during bus fault recovery |
| VDD / VSS | Power supply and ground | Support 2.3–5.5 V operation; VSS must be connected to system ground for proper function |
Key Features
| Feature | Design Value |
|---|---|
| Individually controllable channels | Each of eight A↔B paths can be enabled/disabled independently via control register bits B0–B7 |
| Hot-insertion support | Enables safe addition/removal of I²C peripherals without disrupting master or other segments |
| No glitch on power-up | Internal POR initializes all channels to open state - prevents unintended bus contention at startup |
| Low standby current | 0.1 µA typical at VDD = 3.6 V - critical for battery-backed or always-on monitoring systems |
| Voltage translation capability | Vo(sw) ≤ 2.8 V at VDD = 3.3 V enables reliable level-shifting between 5 V and 3.3 V I²C domains |
Applications
| Server Baseboard Management | Industrial Sensor Hub |
|---|---|
Use Scenario: Isolating multiple temperature, fan, and voltage monitors on separate I²C branches behind a single BMC controller. IC Role / Device Role / Timing Role: I²C multiplexer managing concurrent access to 8 distinct sensor groups without bus collision. Use Value: Enables deterministic polling sequence and fault containment - failure in one sensor branch does not block communication with others. |
Use Scenario: Connecting heterogeneous sensors (e.g., 5 V pressure transducers, 3.3 V humidity ICs, 2.7 V accelerometers) to a single microcontroller I²C port. IC Role / Device Role / Timing Role: Voltage-aware bus switch providing level translation and channel-selective enablement. Use Value: Eliminates need for discrete level shifters per peripheral; reduces BOM count and PCB area by >40% versus discrete solutions. |
| Telecom Line Card Monitoring | Automotive Diagnostic Gateway |
Use Scenario: Routing I²C traffic between central processor and hot-swappable line cards containing EEPROMs, DACs, and PMICs. IC Role / Device Role / Timing Role: Fault-isolating bus switch with RESET-driven recovery for field-replaceable modules. Use Value: Guarantees card insertion/removal does not stall main I²C bus - maintains uptime of control plane functions. |
Use Scenario: Multiplexing diagnostic interfaces (OBD-II, CAN transceiver config, battery monitor) onto a single automotive microcontroller I²C bus. IC Role / Device Role / Timing Role: Robust I²C switch rated for −40 °C to +85 °C ambient and qualified per automotive reliability standards. Use Value: Meets AEC-Q100 stress test requirements for ESD (2000 V HBM) and latch-up (>100 mA), reducing qualification effort. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I²C bus switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TCA9548A | 8-channel I²C switch with identical pinout and control register map; lower Ron (0.75 Ω typ), but only supports 1.65–5.5 V and lacks RESET pin | Preferred where ultra-low insertion loss is required and external reset circuitry is acceptable | Select TCA9548A when minimizing signal degradation is critical and system-level reset handling is already implemented |
| PCA9544A | 4-channel version with same SO24 footprint and RESET functionality; shares identical control logic and voltage range (2.3–5.5 V) | Used where fewer I²C segments are needed - saves cost and simplifies firmware when 8 channels are over-provisioned | Choose PCA9544A for space-constrained designs requiring only four isolated branches and full drop-in compatibility |
Compared with TCA9548A, PCA9549D,112 offers guaranteed bus recovery via dedicated RESET - essential in unattended systems. Versus PCA9544A, it doubles channel count without changing board layout, delivering higher integration density for complex I²C topologies.
Availability
PCA9549D,112 is available at Aetrix Electronics and suitable for server baseboard management, industrial sensor hubs, and telecom line card monitoring requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for PCA9549D,112 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in interface and power management ICs.
The PCA9549D,112 belongs to NXP's I²C-bus switch and multiplexer product line, designed specifically to solve signal integrity, bus contention, and voltage domain bridging challenges in high-density embedded systems.
FAQ
What is the primary function of the PCA9549D,112 in an I²C system?
The PCA9549D,112 acts as an octal bidirectional I²C bus switch that enables or isolates individual A↔B signal paths under software control. Each of its eight channels can be independently enabled via the I²C control register, allowing a single master to communicate with multiple downstream I²C segments without electrical contention. This makes PCA9549D,112 ideal for expanding I²C address space and improving system fault tolerance.
Does the PCA9549D,112 support voltage translation between different I²C domains?
Yes - the PCA9549D,112 exhibits inherent voltage translation capability due to its Vo(sw) characteristic. When powered at 3.3 V, Vo(sw) remains ≤2.8 V, allowing it to safely interface a 5 V master bus with 3.3 V or 2.7 V peripheral buses. This eliminates the need for external level shifters in mixed-voltage I²C systems, and PCA9549D,112 achieves this without additional configuration or external components.
How does the RESET pin on the PCA9549D,112 improve system reliability?
The active LOW RESET pin on PCA9549D,112 forces all eight channels into a high-impedance open state and resets the internal I²C state machine - recovering from conditions where the SCL or SDA line is stuck LOW. This hardware-level recovery avoids firmware hangs and enables autonomous bus restoration, making PCA9549D,112 especially valuable in remote or mission-critical deployments where manual intervention is impractical.
What package type is used for the PCA9549D,112, and is it RoHS-compliant?
The PCA9549D,112 is packaged in SO24 (SOT137-1): a 24-pin plastic small outline package with 7.5 mm body width and gull-wing leads. Per NXP's ordering information and packaging documentation, PCA9549D,112 is lead-free and RoHS-compliant, meeting JEDEC J-STD-020 moisture sensitivity Level 1 (MSL-1) requirements for reflow soldering.
Can the PCA9549D,112 be used in hot-swap applications?
Yes - the PCA9549D,112 explicitly supports hot insertion per its datasheet features. Its low ON-resistance, no-glitch power-up behavior, and ability to isolate live I²C segments make it suitable for modular systems where peripherals are added or removed while powered. When a new module is connected, PCA9549D,112 keeps its associated channel disabled until firmware explicitly enables it, preventing bus conflicts during plug-in events.
PCA9549D,112 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Applications:
- Translating Switch
- Interface:
- I2C, SMBus
- Voltage - Supply:
- 2.3V ~ 3.6V, 4.5V ~ 5.5V
- Supplier Device Package:
- 24-SO
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
PCA9549D,112 FAQ
1.How can I place an order for PCA9549D,112 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCA9549D,112 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for PCA9549D,112 reliable?
The price and inventory of PCA9549D,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCA9549D,112 is usually 5 days.
3.What payment methods are accepted for PCA9549D,112?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCA9549D,112 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCA9549D,112?
PCA9549D,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCA9549D,112 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for PCA9549D,112?
For technical support, including PCA9549D,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCA9549D,112 requirements.
6.How does Aetrix verify that PCA9549D,112 is sourced from the original manufacturer or authorized distributors?
All PCA9549D,112 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PCA9549D,112 meets industry standards.
7.What is the process for return or replacement of PCA9549D,112?
All PCA9549D,112 units undergo pre-shipment inspection (PSI). If there is an issue with PCA9549D,112, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The PCA9549D,112 part is unused and in its original packaging.
Return procedure for PCA9549D,112:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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