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NXP Semiconductors PCA9541AD/03,118
- Part No.:
- PCA9541AD/03,118
- Manufacturer:
- NXP Semiconductors
- Category:
- Specialized
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
PCA9541AD/03,118.pdf
- Description:
- IC INTERFACE SPECIALIZED 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,729
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Product details
Overview
PCA9541AD/03,118 from NXP Semiconductors is a 2-to-1 bidirectional I²C-bus master selector IC designed for high-reliability dual-master systems where uninterrupted slave access must be maintained during master failure or hot-swap maintenance. It features no-channel-selected-at-power-up behavior, active-low reset and interrupt logic, bus recovery initialization (9-clock + NACK + STOP), and voltage-level translation across 1.8 V to 5 V domains. It enables failover control in redundant server management controllers.
For engineers reviewing the PCA9541AD/03,118 datasheet, PCA9541AD/03,118 pinout, PCA9541AD/03,118 application, or PCA9541AD/03,118 equivalent, key selection criteria include its power-up state (no channel selected), bus sensor–driven interrupt on non-idle switching, dual independent interrupt outputs (INT0/INT1), 4-bit hardware address configuration, and support for 400 kHz I²C operation with 6 V-tolerant I/O pins.
Technical Context
The PCA9541AD/03,118 implements a deterministic, arbitration-free channel selection mechanism using two independent CONTROL registers-one per upstream master-with bus switching triggered only upon receipt of a STOP condition. Its internal bus sensor detects downstream SCL/SDA activity and asserts BUSOK interrupt if switching occurs mid-transaction when bus recovery is disabled.
It integrates dedicated interrupt logic that propagates INT_IN to both INT0 and INT1 (when enabled), supports masking per-interrupt type (BUSLOST/BUSOK/BUSINIT/INTIN), and performs automatic 9-pulse bus initialization with SDA release and STOP generation before channel handover-ensuring downstream slaves exit undefined states without hardware reset.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| I²C clock frequency | 0 Hz to 400 kHz - supports standard and fast-mode I²C timing without external clock conditioning |
| Supply voltage range | 2.3 V to 5.5 V - enables direct integration into mixed-voltage systems (e.g., 3.3 V master + 5 V slave rails) |
| I/O voltage tolerance | 6.0 V tolerant - allows safe interfacing with higher-voltage peripherals without level-shifter circuitry |
| Power-up state | No channel selected - ensures neither master gains control at startup; explicit software arbitration required |
| Interrupt outputs | 2 active-low outputs (INT0, INT1) - provide per-master bus ownership status and recovery completion signaling |
| Address inputs | 4 hardware-configurable pins (A0–A3) - enable up to 16 devices on same I²C bus without address conflict |
| Bus recovery sequence | 9 SCL pulses + NACK + STOP - resets downstream slave state machines without requiring dedicated reset lines |
Pinout & Package
PCA9541AD/03,118 is supplied in SO16 package (SOT109-1): plastic small outline, 16 leads, 3.9 mm body width, surface-mount compatible.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INT0 | Active-low interrupt output 0 | Signals bus ownership change, recovery completion, or non-idle switch event to Master 0 |
| SDA_MST0 | Serial data line for Master 0 | Bidirectional I²C data path; requires external pull-up; 6 V tolerant |
| SCL_MST0 | Serial clock line for Master 0 | Bidirectional I²C clock path; requires external pull-up; 6 V tolerant |
| RESET | Active-low reset input | Resets internal state machine and register bank to default; overrides POR |
| SCL_MST1 | Serial clock line for Master 1 | Bidirectional I²C clock path; requires external pull-up; 6 V tolerant |
| SDA_MST1 | Serial data line for Master 1 | Bidirectional I²C data path; requires external pull-up; 6 V tolerant |
| INT1 | Active-low interrupt output 1 | Signals bus ownership change, recovery completion, or non-idle switch event to Master 1 |
| VSS | Supply ground | Primary reference for all digital and analog circuitry; must be low-impedance connection |
| A0–A3 | Hardware address inputs | Set 4-bit slave address; externally pulled HIGH/LOW; no internal pull-ups |
| SCL_SLAVE | Downstream serial clock | Connects to shared slave I²C bus; passes SCL with minimal propagation delay |
| SDA_SLAVE | Downstream serial data | Connects to shared slave I²C bus; passes SDA with minimal propagation delay |
| INT_IN | Active-low interrupt input | Collects downstream interrupt signals and propagates to both INT0/INT1 when enabled |
| VDD | Supply voltage | Power source for internal logic and pass-gate biasing; sets maximum passed voltage level |
Key Features
| Feature | Design Value |
|---|---|
| No-channel-selected power-up | Eliminates race condition at boot; forces explicit software arbitration before first bus access |
| Dual independent interrupt outputs | Enables per-master asynchronous notification of bus ownership, recovery completion, and error conditions |
| Configurable bus recovery sequence | 9-clock pulse + NACK + STOP ensures reliable slave reinitialization without hardware reset pins |
| Downstream bus traffic sensor | Detects non-idle switching and triggers BUSOK interrupt-alerting master to perform external recovery |
| Voltage-level translation | VDD-limited pass gates allow interoperability between 1.8 V, 2.5 V, 3.3 V, and 5 V I²C domains |
Applications
| Redundant Server Management | Industrial PLC Dual-Controller Systems |
|---|---|
Use Scenario: Two BMCs (Baseboard Management Controllers) share access to temperature sensors, fan controllers, and power monitors via a single I²C bus. IC Role / Device Role / Timing Role: PCA9541AD/03,118 acts as failover arbiter-granting exclusive bus access to primary BMC until fault detection, then transferring control to backup BMC without bus lockup. Use Value: Enables zero-downtime maintenance and hot-swap of controller cards while preserving telemetry continuity and thermal safety monitoring. | Use Scenario: Primary and backup PLC CPUs coordinate control of motor drives and I/O modules over a shared fieldbus I²C segment. IC Role / Device Role / Timing Role: PCA9541AD/03,118 serves as deterministic bus gatekeeper-preventing simultaneous master access that could corrupt register writes or cause ACK collisions. Use Value: Guarantees deterministic bus handover within <100 µs after STOP command, eliminating arbitration delays and ensuring real-time response consistency. |
| Telecom Line Card Redundancy | Medical Diagnostic Equipment Dual-Host Interface |
Use Scenario: Active/standby line cards in carrier-grade switches share calibration EEPROMs and optical transceiver monitors via one I²C bus. IC Role / Device Role / Timing Role: PCA9541AD/03,118 isolates failed line card electrically and logically-preventing bus contention and enabling seamless switchover during firmware updates. Use Value: Maintains uninterrupted link monitoring and laser bias calibration during field upgrades, meeting ITU-T G.8262 holdover requirements. | Use Scenario: Diagnostic imaging subsystem uses dual host processors (control + safety monitor) accessing shared sensor arrays and ADCs over I²C. IC Role / Device Role / Timing Role: PCA9541AD/03,118 enforces strict bus ownership separation-ensuring safety-critical monitor processor can interrupt and seize bus during anomaly detection. Use Value: Supports IEC 62304 Class C software safety requirements by guaranteeing atomic bus takeover and preventing concurrent access to safety-critical peripherals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar I²C master selector applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| PCA9541APW/03,118 | TSSOP16 package (4.4 mm width); identical electrical specs and register map; lower thermal resistance than SO16 | Better suited for space-constrained PCBs with tight layout rules; same functional behavior as PCA9541AD/03,118 | Select when board area or thermal performance outweighs cost sensitivity; pin-compatible but requires footprint revision. |
| PCA9541ABS/03,118 | HVQFN16 package (4 × 4 × 0.85 mm); exposed thermal pad; identical logic and timing; enhanced thermal dissipation | Required for high-density, thermally demanding environments (e.g., 1U servers); supports higher ambient operating temperatures | Choose for applications exceeding 70 °C ambient or requiring >100 khr MTBF; not drop-in-requires thermal pad routing and solder stencil design. |
Compared with PCA9541AD/03,118, the TSSOP variant offers smaller footprint and improved thermal performance in same-function applications, while the HVQFN version delivers superior power dissipation and reliability in thermally constrained deployments-both retain identical register-level control, interrupt behavior, and bus recovery functionality.
Availability
PCA9541AD/03,118 is available at Aetrix Electronics and suitable for redundant server management, industrial PLC dual-controller systems, and telecom line card redundancy requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for PCA9541AD/03,118 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.
The PCA9541A product line was developed to solve deterministic bus arbitration challenges in high-availability dual-master I²C systems-enabling seamless failover, hot-swap capability, and voltage-domain bridging without external logic or microcontroller intervention.
FAQ
What is the power-up behavior of the PCA9541AD/03,118?
The PCA9541AD/03,118 powers up with no channel selected-neither Master 0 nor Master 1 is connected to the downstream slave bus. This prevents unintended bus access at startup and requires explicit software configuration via I²C write to the CONTROL register before either master can assume control. The PCA9541AD/03,118 differs from the /01 variant, which defaults to Channel 0.
How does the PCA9541AD/03,118 handle bus recovery during channel switching?
The PCA9541AD/03,118 supports two recovery modes: (1) Built-in bus initialization-9 SCL pulses + NACK + STOP sent to SCL_SLAVE/SDA_SLAVE before switching; (2) Bus traffic sensor mode-generates BUSOK interrupt if switching occurs on non-idle bus, indicating external recovery is needed. Mode selection is controlled via BUSINIT bit in the CONTROL register.
Can the PCA9541AD/03,118 interface between 3.3 V and 5 V I²C buses?
Yes. The PCA9541AD/03,118 uses VDD-limited pass gates: when VDD = 3.3 V, it passes up to 3.3 V signals; when VDD = 5 V, it passes up to 5 V. This allows safe bidirectional communication between 1.8 V, 2.5 V, 3.3 V, and 5 V I²C domains without external level shifters. All I/O pins are 6 V tolerant.
What is the function of the INT_IN pin on the PCA9541AD/03,118?
The INT_IN pin is an active-low interrupt input that collects asynchronous interrupt signals from downstream slave devices (e.g., sensor alerts or fault flags). When enabled via the INTINMSK bit in the IE register, PCA9541AD/03,118 propagates this signal to both INT0 and INT1 outputs-allowing upstream masters to respond to slave-initiated events without polling.
Does the PCA9541AD/03,118 require external pull-up resistors on all I²C lines?
Yes. The PCA9541AD/03,118 has no internal pull-up resistors. External pull-up resistors are required on SCL_MST0, SDA_MST0, SCL_MST1, SDA_MST1, SCL_SLAVE, SDA_SLAVE, INT0, INT1, INT_IN, and RESET. Pull-up voltage must match the respective bus domain (e.g., 3.3 V for Master 0, 5 V for slaves), and resistor values must be selected per I²C speed and total bus capacitance.
PCA9541AD/03,118 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Applications:
- 2-Channel I2C Multiplexer
- Interface:
- I2C, SMBus
- Voltage - Supply:
- 2.3V ~ 5.5V
- Supplier Device Package:
- 16-SO
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
PCA9541AD/03,118 FAQ
1.How can I place an order for PCA9541AD/03,118 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCA9541AD/03,118 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 PCA9541AD/03,118 reliable?
The price and inventory of PCA9541AD/03,118 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCA9541AD/03,118 is usually 5 days.
3.What payment methods are accepted for PCA9541AD/03,118?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCA9541AD/03,118 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCA9541AD/03,118?
PCA9541AD/03,118 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCA9541AD/03,118 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 PCA9541AD/03,118?
For technical support, including PCA9541AD/03,118 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCA9541AD/03,118 requirements.
6.How does Aetrix verify that PCA9541AD/03,118 is sourced from the original manufacturer or authorized distributors?
All PCA9541AD/03,118 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 PCA9541AD/03,118 meets industry standards.
7.What is the process for return or replacement of PCA9541AD/03,118?
All PCA9541AD/03,118 units undergo pre-shipment inspection (PSI). If there is an issue with PCA9541AD/03,118, 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 PCA9541AD/03,118 part is unused and in its original packaging.
Return procedure for PCA9541AD/03,118:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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