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Texas Instruments PCA8550D
- Part No.:
- PCA8550D
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
PCA8550D.pdf
- Description:
- MUX, 8550 SERIES, 4 LINE INPUT
- Quantity:
- Payment:
- Shipping:
Inventory:4,840
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Product details
Overview
PCA8550D from Texas Instruments is a nonvolatile 5-bit register with I2C interface and integrated 4-bit 1-of-2 multiplexer, designed for 3-V to 3.6-V VCC operation. It provides 2.5-V MUX OUT outputs, a 3.3-V NON-MUXED OUT, write-protect (WP) and OVERRIDE control inputs, and supports fast-mode (400 kbit/s) I2C communication for jumperless PC motherboard configuration.
For engineers reviewing the PCA8550D datasheet, PCA8550D pinout, PCA8550D application, or PCA8550D equivalent, key selection considerations include its nonvolatile register retention (≥10 years), guaranteed 1000 write cycles, 5-V-tolerant I2C inputs with integrated pullups, monotonic power-up initialization, and SOIC-16 package compatibility with industrial temperature range (0°C to 70°C).
Technical Context
The PCA8550D implements an I2C slave interface with fixed 7-bit address 1001110 (0x4E), supporting standard-mode (100 kbit/s) and fast-mode (400 kbit/s) timing. Its internal nonvolatile register stores five bits: four for MUX OUT A–D and one latched NON-MUXED OUT value, with factory default all-low.
Operation requires monotonic VCC ramp through 1.1 V–2.5 V at power-up to initialize the nonvolatile registers and I2C state machine. The OVERRIDE input forces all outputs low asynchronously, while WP enables/disables register writes based on its level during the falling edge of the first valid data byte acknowledge.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 3 V to 3.6 V - defines strict supply rail for reliable 2.5-V MUX OUT and 3.3-V NON-MUXED OUT voltage levels |
| I2C Speed | Up to 400 kbit/s - enables high-throughput configuration updates without bus contention in dense embedded systems |
| Nonvolatile Retention | ≥10 years - ensures persistent board configuration across power cycles and long-term deployment without refresh |
| Write Endurance | ≥1000 cycles - supports field-updatable settings in manufacturing test, calibration, or firmware-driven reconfiguration |
| I2C Input Tolerance | 5.5 V max - allows direct connection to 5-V logic buses without level-shifting, simplifying mixed-voltage system integration |
| Propagation Delay | MUX IN to MUX OUT: 20 ns - guarantees sub-25-ns signal routing latency critical for real-time multiplexing decisions |
| Operating Temperature | 0°C to 70°C - validated for commercial-grade PC motherboard and industrial control applications |
Pinout & Package
PCA8550D is housed in a 16-pin SOIC (D) package per JEDEC MS-012, with 1.27-mm pitch, 9.9-mm body width, and 6.0-mm body length. Thermal resistance θJA = 113°C/W enables stable operation under typical PCB copper pour conditions.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | I2C SCL | Serial clock input - Schmitt-triggered, 5-V tolerant, with internal pullup; synchronizes I2C read/write transactions |
| 2 | I2C SDA | Serial data bidirectional line - Schmitt-triggered, 5-V tolerant, with internal pullup; carries address, data, and ACK |
| 3 | OVERRIDE | Asynchronous active-high override - forces all MUX OUT and NON-MUXED OUT signals low regardless of register state |
| 4–7 | MUX IN A–D | Parallel data inputs - routed to corresponding MUX OUT pins when MUX SELECT = H; accept up to 5.5-V logic |
| 8 | GND | Ground reference - common return for VCC, I/O, and internal logic; must be low-impedance for noise immunity |
| 9–10 | VCC | Supply voltage - powers internal logic, EEPROM, and output drivers; requires 3.0–3.6 V with monotonic ramp at startup |
| 11 | WP | Write protect input - disables register writes when high; sampled at falling edge of first data byte acknowledge |
| 12 | NON-MUXED OUT | Latched 3.3-V output - holds last written value during register update; immune to transient changes during I2C writes |
| 13 | MUX SELECT | Multiplexer mode control - L selects register data, H selects parallel MUX IN inputs for MUX OUT A–D |
| 14–17 | MUX OUT A–D | 2.5-V buffered outputs - reflect either register contents (MUX SELECT = L) or MUX IN values (MUX SELECT = H) |
Key Features
| Feature | Design Value |
|---|---|
| Nonvolatile register storage | Retains configuration across power loss without external backup power or battery |
| Integrated 4-bit 1-of-2 multiplexer | Eliminates need for discrete logic or additional ICs to switch between I2C-configured and parallel-controlled outputs |
| 5-V-tolerant I2C interface | Enables direct interfacing with legacy 5-V microcontrollers or FPGAs without external level shifters |
| Monotonic power-up initialization | Guarantees deterministic register and I2C state after cold start, preventing undefined output glitches |
| Dual-output voltage domains | Delivers 2.5-V MUX OUT and 3.3-V NON-MUXED OUT simultaneously for mixed-voltage subsystem interconnect |
Applications
| PC Motherboard Configuration | Industrial Control I/O Expansion |
|---|---|
|
Use Scenario: Jumperless BIOS/UEFI configuration of voltage rails, fan speed profiles, and peripheral enable states on ATX motherboards. IC Role / Device Role / Timing Role: Nonvolatile register stores boot-time hardware settings; I2C interface allows firmware runtime updates without physical access. Use Value: Reduces BOM count by replacing mechanical jumpers and eliminates manual configuration errors during mass production. |
Use Scenario: Remote reconfiguration of sensor input routing and actuator enable signals in PLC backplane modules. IC Role / Device Role / Timing Role: Multiplexer selects between factory-calibrated and field-adjusted analog/digital I/O paths under host controller command. Use Value: Enables field-upgradable I/O mapping without hardware modification or firmware reflashing of main controller. |
| Embedded System Bootloader Interface | Test Fixture Signal Routing |
|
Use Scenario: Secure boot configuration lock-down where WP pin is tied to tamper-detection circuitry to prevent unauthorized register writes. IC Role / Device Role / Timing Role: NON-MUXED OUT drives secure boot enable signal; OVERRIDE forces safe-state shutdown on fault detection. Use Value: Provides hardware-enforced configuration integrity and fail-safe response independent of software execution state. |
Use Scenario: Automated test equipment dynamically routes stimulus signals to DUT pins using MUX IN/OUT controlled via I2C from test sequencer. IC Role / Device Role / Timing Role: MUX SELECT toggles between preloaded register values and real-time parallel inputs for rapid test vector switching. Use Value: Achieves <25 ns propagation delay for high-speed digital pattern generation without FPGA resource overhead. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile I2C register multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| PCA9554PW | 8-bit I2C port expander with no nonvolatile storage; outputs are volatile and reset on power cycle | Suitable only for runtime I/O expansion, not persistent configuration storage | Select PCA9554PW only when configuration persistence is unnecessary and higher pin count is required |
| AT24C02C-SSHM-T | 2-Kbit I2C EEPROM with no integrated multiplexer or logic; requires external GPIO or logic to implement routing | Provides greater storage capacity but adds design complexity for multiplexing functionality | Choose AT24C02C-SSHM-T only when >5-bit storage is needed and discrete multiplexer logic is acceptable |
Compared with PCA9554PW and AT24C02C-SSHM-T, the PCA8550D uniquely integrates nonvolatile 5-bit storage, 4-bit multiplexing, and dual-voltage outputs in a single SOIC-16 package-eliminating external components required by alternatives to achieve equivalent functionality.
Availability
PCA8550D is available at Aetrix Electronics and suitable for PC motherboard design, industrial I/O modules, embedded bootloader security, automated test fixture routing, and field-upgradable control systems requiring stable component supply and long-term lifecycle support.
Supply support for PCA8550D 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
Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, precision, and energy efficiency.
The PCA8550D belongs to TI's legacy interface and logic portfolio, designed specifically to replace mechanical jumpers in PC and industrial platforms by combining nonvolatile configuration storage with hardware-multiplexed I/O routing.
FAQ
What is the I2C slave address of the PCA8550D?
The PCA8550D uses a fixed 7-bit I2C slave address of 1001110 (0x4E), with the R/W bit appended as the eighth bit. This address is hardwired and not configurable; the device does not respond to the general call address. Communication begins with a START condition followed by this address byte, and the PCA8550D responds with an ACK only when the full 8-bit address matches its internal value. The PCA8550D datasheet confirms this address in the I2C Interface Definition Table.
Does the PCA8550D require external pull-up resistors on SCL and SDA lines?
No, the PCA8550D includes integrated pull-up resistors on both SCL and SDA pins, eliminating the need for external components. These internal pullups are sized to support standard-mode (100 kbit/s) and fast-mode (400 kbit/s) I2C operation within specified bus capacitance limits (≤400 pF). The PCA8550D datasheet explicitly states "integrated pullup resistors" in the FEATURES section and confirms 5-V tolerance, allowing interoperability with mixed-voltage I2C masters without additional level-shifting circuitry.
How does the OVERRIDE function interact with the nonvolatile register contents in the PCA8550D?
The OVERRIDE input in the PCA8550D operates asynchronously and independently of the nonvolatile register state: when asserted high, it forces all MUX OUT A–D and NON-MUXED OUT signals low regardless of stored register values or MUX SELECT state. This override persists until OVERRIDE returns low, at which point outputs immediately resume reflecting the current register or MUX IN values. The PCA8550D datasheet specifies this behavior in the FUNCTION TABLE and LOGIC DIAGRAM, confirming that OVERRIDE bypasses all internal logic paths.
What is the write time for the nonvolatile register in the PCA8550D?
The PCA8550D requires a typical write time (twr) of 10 ms to commit data from the I2C interface into its nonvolatile memory cell. During this period, the device does not acknowledge its slave address, preventing bus collisions. The PCA8550D datasheet lists this value in the Nonvolatile Storage Specifications table and emphasizes that writing occurs only after a valid STOP condition and only if WP is low during the falling edge of the first data byte acknowledge. No external timing control is needed-the internal state machine manages the entire write sequence.
Can the PCA8550D operate with a 5-V supply on VCC?
No, the PCA8550D is rated for VCC operation strictly between 3.0 V and 3.6 V, as defined in the Recommended Operating Conditions table. Applying 5 V to VCC exceeds the absolute maximum rating of 6.5 V but violates the functional specification and risks incorrect output voltage levels (MUX OUT is specified as 2.5 V, NON-MUXED OUT as 3.3 V), timing violations, or accelerated wear. While I2C inputs tolerate 5.5 V, VCC must remain within 3.0–3.6 V for guaranteed operation-this constraint is explicitly stated in the PCA8550D datasheet's "Recommended Operating Conditions" section.
PCA8550D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Multiplexer
- Circuit:
- 1 x 4:4
- Independent Circuits:
- 1
- Current - Output High, Low:
- 2mA, 2mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
PCA8550D FAQ
1.How can I place an order for PCA8550D through Aetrix?
Please submit a Request for Quotation (RFQ) for PCA8550D 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 PCA8550D reliable?
The price and inventory of PCA8550D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCA8550D is usually 5 days.
3.What payment methods are accepted for PCA8550D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCA8550D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCA8550D?
PCA8550D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCA8550D 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 PCA8550D?
For technical support, including PCA8550D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCA8550D requirements.
6.How does Aetrix verify that PCA8550D is sourced from the original manufacturer or authorized distributors?
All PCA8550D 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 PCA8550D meets industry standards.
7.What is the process for return or replacement of PCA8550D?
All PCA8550D units undergo pre-shipment inspection (PSI). If there is an issue with PCA8550D, 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 PCA8550D part is unused and in its original packaging.
Return procedure for PCA8550D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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