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NXP Semiconductors PCA9556PW,112
- Part No.:
- PCA9556PW,112
- Manufacturer:
- NXP Semiconductors
- Category:
- I/O Expanders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
PCA9556PW,112.pdf
- Description:
- IC XPND 100KHZ I2C SMBUS 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,998
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Product details
Overview
PCA9556PW,112 from NXP Semiconductors (formerly Philips) is an octal SMBus/I²C registered I/O expander IC used for parallel digital I/O expansion in embedded control systems. It features 8 configurable I/O pins (I/O0–I/O7), a 3.0–5.5 V supply range, active-low RESET, and SMBus-compliant fixed 3.3 V logic levels - enabling reliable interface with microcontrollers in server management, industrial PLCs, and power supply monitoring.
For engineers reviewing the PCA9556PW,112 datasheet, PCA9556PW,112 pinout, PCA9556PW,112 application, or PCA9556PW,112 equivalent, key selection criteria include its open-drain I/O0 configuration, polarity inversion register, internal power-on reset, and TSSOP-16 package compatibility with space-constrained SMBus node designs.
Technical Context
The PCA9556PW,112 implements an SMBus-compatible I²C slave interface with four internal registers: input port (read-only), output port, polarity inversion, and configuration. Its SMBus address is programmable via A0–A2 pins (base 0x38–0x3F), and it supports Write Byte and Read Byte protocols per SMBus v1.1.
Each of the eight I/Os is individually configurable as input or output via the configuration register; I/O0 defaults to high-impedance open-drain, while I/O1–I/O7 support push-pull outputs with ±20 mA drive capability. The device includes noise filtering on SCL/SDA, internal power-on reset (VPOR = 1.3–2.4 V), and external active-low RESET with 2 ns minimum pulse width.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0 V – 5.5 V - supports dual-rail systems and direct interfacing with 3.3 V or 5 V microcontrollers without level shifters. |
| SMBus/I²C Frequency | 10 kHz – 100 kHz - compatible with standard-mode I²C and SMBus timing, including tLOW ≥ 4.7 µs and tHIGH ≥ 4.0 µs. |
| I/O Configuration | 8-bit programmable direction register - enables dynamic reassignment of each pin as input or output during runtime. |
| I/O0 Output Type | High-impedance open drain - allows wired-AND bus topology and safe connection to higher-voltage rails up to 4.6 V. |
| Reset Function | Active-low synchronous RESET pin with internal power-on reset - ensures deterministic register initialization without cycling VDD. |
| Polarity Inversion | 8-bit active-high inversion register - permits software-reversed input logic without external inverters or firmware bit-flipping. |
| ESD Protection | 2000 V HBM, 200 V MM, 1000 V CDM - meets industrial handling requirements and reduces board-level ESD mitigation overhead. |
Pinout & Package
PCA9556PW,112 is housed in a 16-pin plastic TSSOP package (SOT403-1), 4.4 mm body width, lead pitch 0.65 mm, RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCL | Serial clock input | Accepts SMBus/I²C clock signal; includes internal noise filter for robust operation in electrically noisy environments. |
| SDA | Serial data bidirectional line | Open-drain I/O shared across SMBus master/slave; requires external pull-up resistor per bus specification. |
| A0–A2 | Slave address inputs | Set 3 LSBs of 7-bit SMBus address (0x38–0x3F); allow up to 8 devices on same bus without address conflict. |
| I/O0 | Configurable I/O (open drain) | Default high-impedance open drain - supports interrupt signaling, status flagging, or wired-AND bus arbitration. |
| I/O1–I/O7 | Configurable I/O (push-pull) | Individually settable as input or output; sink/source up to ±20 mA per pin under thermal limits. |
| VSS | Ground reference | Primary return path for all I/O and internal logic; must be low-impedance connection to system GND plane. |
| VDD | Power supply | Single-supply input (3.0–5.5 V); powers internal logic, I/O drivers, and SMBus interface circuitry. |
| RESET | Active-low asynchronous reset | Forces all registers to default state (all I/Os as inputs, polarity bits = 0x0F, output = 0x00) without power cycle. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable I/O direction | Per-pin configuration via register 3 enables flexible hardware reuse - e.g., repurpose I/O2 as LED driver or sensor input without PCB change. |
| Polarity inversion register | Active-high bits (register 2) invert input logic levels - simplifies firmware handling of active-low sensors or switches without software XOR. |
| No-glitch power-up behavior | Internal power-on reset ensures all I/Os start as high-impedance inputs - prevents unintended output states during boot sequence. |
| Low standby current | 25–100 µA at Tamb = –40 to +85 °C - suitable for battery-backed or always-on monitoring nodes requiring minimal quiescent draw. |
| Input noise filtering | Integrated RC filter on SCL/SDA pins suppresses sub-50 ns transients - eliminates false clock/data edges in industrial EMI environments. |
Applications
| Server Baseboard Management | Industrial PLC I/O Expansion |
|---|---|
|
Use Scenario: Monitoring chassis intrusion, fan presence, and power supply OK signals in IPMI-compliant server motherboards. IC Role / Device Role / Timing Role: SMBus slave I/O expander providing 8-bit status input capture synchronized to host-initiated Read Byte transactions. Use Value: Eliminates need for discrete GPIOs on BMC; leverages existing SMBus infrastructure for low-pin-count, low-overhead monitoring. |
Use Scenario: Adding isolated digital inputs/outputs to compact PLC modules controlling solenoids, limit switches, and indicator LEDs. IC Role / Device Role / Timing Role: Configurable parallel I/O peripheral controlled via I²C from main MCU, supporting real-time polling or interrupt-driven I/O0 edge detection. Use Value: Reduces MCU GPIO usage by 8 pins; open-drain I/O0 enables direct connection to 24 V industrial sensors without external level translation. |
| DC-DC Power Supply Sequencing | Embedded System Status Panel |
|
Use Scenario: Coordinating startup/shutdown sequencing of multiple voltage rails using discrete enable/disable signals and fault flags. IC Role / Device Role / Timing Role: Output port register drives rail-enable MOSFET gates; input port reads PG (power-good) signals with polarity inversion for active-low feedback. Use Value: Enables centralized sequencing logic in firmware; avoids dedicated sequencer ICs and reduces BOM count. |
Use Scenario: Driving multi-color status LEDs and reading DIP switch settings on network appliance front panels. IC Role / Device Role / Timing Role: I/O1–I/O7 configured as LED drivers (sink mode), I/O0 used as interrupt-capable input for switch changes. Use Value: Single-chip solution replaces discrete transistors and buffers; polarity inversion simplifies DIP switch wiring (active-low logic). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I/O expander applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| PCA9557PW,112 | Pin-for-pin replacement with enhanced ESD (4 kV HBM), lower standby current (10 µA typ), and identical register map. | Same SMBus/I²C interface and I/O functionality; preferred for new designs requiring improved robustness and lower power. | Select PCA9557PW,112 when upgrading for reliability or power-sensitive applications; drop-in compatible with no layout change. |
| TCA6408APWR | TI 8-bit I²C expander with 1.65–5.5 V supply, no SMBus-specific features (e.g., timeout reset), and different register addressing. | Lacks SMBus compliance and active-low RESET; requires firmware adaptation for reset handling and address decoding. | Choose TCA6408APWR only if SMBus-specific functions (e.g., host-initiated reset) are unused and voltage flexibility below 3.0 V is required. |
Compared with PCA9556PW,112, PCA9557PW,112 offers superior ESD immunity and lower quiescent current while maintaining full functional and pin compatibility; TCA6408APWR provides broader voltage range but omits SMBus protocol extensions and hardware reset, increasing firmware complexity in managed systems.
Availability
PCA9556PW,112 is available at Aetrix Electronics and suitable for server management, industrial PLCs, DC-DC sequencing, and embedded status panel applications requiring stable component supply and long-term industrial temperature support (–40 °C to +85 °C).
Supply support for PCA9556PW,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, formerly Philips Semiconductors, is a global leader in high-performance mixed-signal ICs, with core expertise in automotive, industrial, and communication applications.
The PCA9556PW,112 belongs to NXP's legacy SMBus/I²C interface portfolio, designed specifically for low-pin-count, low-power digital I/O expansion in resource-constrained embedded systems requiring standardized bus interoperability.
FAQ
What is the SMBus address range supported by the PCA9556PW,112?
The PCA9556PW,112 supports seven programmable SMBus addresses (0x38–0x3E) via A0–A2 pins, with the base address fixed at 0x38. Address 0x3F is reserved for general call. This allows up to seven PCA9556PW,112 devices on a single SMBus segment without address collision, provided A0–A2 are uniquely configured per device.
Does the PCA9556PW,112 require external pull-up resistors on SCL and SDA lines?
Yes, the PCA9556PW,112 requires external pull-up resistors on both SCL and SDA lines to ensure proper SMBus/I²C bus operation. The device has open-drain outputs on these pins, and typical values range from 1.8 kΩ to 10 kΩ depending on bus capacitance and speed - consistent with SMBus v1.1 specifications referenced in the PCA9556PW,112 datasheet.
How does the polarity inversion register affect input readings on the PCA9556PW,112?
The polarity inversion register (register 2) in the PCA9556PW,112 flips the logic level of corresponding input pins before they appear in the input port register. For example, if I/O2 is configured as an input and bit N2 = 1, a physical LOW on I/O2 reads as HIGH in register 0 - enabling direct firmware interpretation of active-low signals without software bit manipulation in the PCA9556PW,112 application layer.
Can I/O0 of the PCA9556PW,112 be used as a standard push-pull output?
No, I/O0 of the PCA9556PW,112 is internally hardwired as a high-impedance open-drain output and cannot be configured as a push-pull driver. Its design purpose is for wired-AND applications such as interrupt signaling or status flagging; attempting to drive it as a source will not yield valid logic HIGH levels, and the PCA9556PW,112 datasheet explicitly specifies VOH ≤ 1 µA at 4.6 V.
What is the maximum total sink current allowed for all I/O pins on the PCA9556PW,112?
The PCA9556PW,112 specifies a maximum total sink current of 54 mA at +85 °C and 80 mA at +70 °C across all I/O pins (I/O1–I/O7). This thermal derating is defined in the DC Characteristics table and applies regardless of individual pin current - exceeding this limit risks thermal shutdown or parametric drift, so system design must aggregate worst-case loads when using the PCA9556PW,112 in high-drive configurations.
PCA9556PW,112 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Number of I/O:
- 8
- Interface:
- I2C, SMBus
- Interrupt Output:
- Yes
- Features:
- POR
- Output Type:
- Open Drain, Push-Pull
- Current - Output Source/Sink:
- 10mA, 20mA
- Clock Frequency:
- 100 kHz
- Voltage - Supply:
- 3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
PCA9556PW,112 FAQ
1.How can I place an order for PCA9556PW,112 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCA9556PW,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 PCA9556PW,112 reliable?
The price and inventory of PCA9556PW,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCA9556PW,112 is usually 5 days.
3.What payment methods are accepted for PCA9556PW,112?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCA9556PW,112 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCA9556PW,112?
PCA9556PW,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCA9556PW,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 PCA9556PW,112?
For technical support, including PCA9556PW,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCA9556PW,112 requirements.
6.How does Aetrix verify that PCA9556PW,112 is sourced from the original manufacturer or authorized distributors?
All PCA9556PW,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 PCA9556PW,112 meets industry standards.
7.What is the process for return or replacement of PCA9556PW,112?
All PCA9556PW,112 units undergo pre-shipment inspection (PSI). If there is an issue with PCA9556PW,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 PCA9556PW,112 part is unused and in its original packaging.
Return procedure for PCA9556PW,112:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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