PCA9541APW/01 - 2-to-1 I2C Master Selector, 16-TSSOP | NXP
Référence : PCA9541APW/01 ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $4.2 | $4,20 |
| 10 | $3.78 | $37,80 |
| 100 | $3.2 | $320,00 |
| 500 | $2.65 | $1 325,00 |
| 1 000 | $2.2 | $2 200,00 |
PCA9541APW/01 Présentation
A 2-to-1 I2C master selector belongs to the broader family of I2C switches and multiplexers, which are themselves a subcategory of serial interface ICs used for digital inter-chip communication. The PCA9541APW/01 specifically enables bus-arbiter functionality by routing one of two upstream master controllers (e.g., a primary and a redundant back-up) onto a single downstream I2C bus segment. It sits between the master controllers and downstream peripherals, providing arbitration, fault isolation, and hot-swap capability.
Key features include two upstream I2C channels (SCL0/SDA0 and SCL1/SDA1), one downstream I2C channel (SCL/SDA), an active-low RESET input, hardware-selectable channel at power-up via a startup mode pin, and bidirectional interrupt logic with separate INT0 and INT1 outputs that report which master currently controls the bus. The downstream INT_IN pin collects fault information from peripherals and propagates it upstream when enabled.
The device operates from a supply voltage compatible with common 2.3V-5.5V rails and supports standard-mode and fast-mode I2C signaling. Its low on-resistance pass gates and channel-isolation logic keep bus capacitance low, ensuring clean rise/fall times even with long downstream traces. The PCA9541APW/01 variant pre-selects channel 0 at startup, while the /03 variant leaves no channel selected at startup - selection between /01 and /03 lets system designers tune the power-on behavior.
Typical applications include redundant server backplanes with dual master controllers, fault-tolerant telecom equipment, hot-swappable controller cards, and industrial PLC systems where two CPUs arbitrate access to shared I2C peripherals. It is also used in RAID storage controllers and ATCA/AdvancedTCA shelf managers that require seamless master failover.
When designing with this part, ensure pull-up resistors are present on the active upstream channel and the downstream bus, and follow the standard I2C impedance guidelines because the pass gates do not include internal pull-ups. Decoupling of VCC with a 100nF ceramic capacitor close to pin 16 is recommended.
This page synthesizes verified distributor pricing, drop-in alternatives, and practical design notes that complement the manufacturer datasheet.
Alternatives de remplacement direct pour PCA9541APW/01 — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
PCA9541APW/03
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
PCA9541APW/01,118
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
PCA9541APW/01,112
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
PCA9541APW,112
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
PCA9541APW,118
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
PCA9541APW/01 Spécifications
| Fonction | 2-to-1 I2C-bus master selector |
| Number of Masters Supported | 2 (with arbitration) |
| Number of Downstream Channels | 1 |
| I2C Bus Modes Supported | Standard-mode, Fast-mode |
| Startup Channel Selection | Channel 0 pre-selected (PCA9541A/01) |
| Interrupt Outputs | INT0, INT1 (open-drain) |
| Interrupt Input | INT_IN (downstream to upstream) |
| Reset Input | Active-low RESET |
| Supply Voltage Range | 2.3 V to 5.5 V |
| Plage de température de fonctionnement | -40 C to +85 C |
| Boîtier | 16-pin TSSOP (SOT403-1, 4.4 mm) |
| Type de montage | Surface Mount |
| Niveau MSL | 1 (unlimited floor life) |
| Statut RoHS | Compliant |
| Lead-Free / Halogen-Free | Yes / Yes |
Configuration des broches de PCA9541APW/01
| Broche 1 | SCL0 — Upstream I2C clock for master 0 |
| Broche 2 | SDA0 — Upstream I2C data for master 0 |
| Broche 3 | INT0 — Interrupt output for master 0 (open-drain) |
| Broche 4 | INT1 — Interrupt output for master 1 (open-drain) |
| Broche 5 | INT_IN — Downstream-to-upstream interrupt input |
| Broche 6 | RESET — Active-low reset input |
| Broche 7 | AD0 / CTRL — Address or control pin (see datasheet) |
| Broche 8 | GND — Ground |
| Broche 9 | SCL — Downstream I2C clock |
| Broche 10 | SDA — Downstream I2C data |
| Broche 11 | SCL1 — Upstream I2C clock for master 1 |
| Broche 12 | SDA1 — Upstream I2C data for master 1 |
| Broche 13 | NC — Not connected (per datasheet) |
| Broche 14 | NC — Not connected (per datasheet) |
| Broche 15 | NC — Not connected (per datasheet) |
| Broche 16 | VCC — Supply voltage (2.3 V to 5.5 V) |
Applications typiques
PCA9541APW/01 convient pour 6 applications: Redundant Server Backplane with Dual Master Controllers, Hot-Swappable Controller Cards in Telecom Equipment, ATCA / AdvancedTCA Shelf Manager Arbitration, RAID Storage Controllers with Dual-BMC Redundancy, Industrial PLC Systems with Dual CPU Arbitration, Fault-Tolerant Medical Device Controllers.
Redundant Server Backplane with Dual Master Controllers
The PCA9541APW/01 fits redundant server backplane designs because it arbitrates between two upstream master controllers and grants a single downstream bus to whichever master is active. Its 4.4 uA typical quiescent current at 3.3V (per the manufacturer datasheet) keeps backplane standby draw minimal, and the /01 variant's channel-0 pre-selection ensures the primary BMC takes control immediately after power-on. Compared to discrete arbitration logic, the integrated INT0/INT1 outputs reduce GPIO count and the built-in RESET input provides deterministic failover recovery during firmware watchdog events.
Recommandé
Hot-Swappable Controller Cards in Telecom Equipment
Hot-swappable controller cards in telecom shelves benefit from the PCA9541APW/01's automatic activity detection and rerouting. When a controller card is pulled for maintenance, the device detects loss of SCL/SDA activity on that channel and seamlessly hands downstream bus control to the surviving master. The active-low RESET pin lets the system force deterministic channel selection during card-insertion events. Its 16-pin TSSOP package and 2.3V-5.5V supply range simplify integration into both 3.3V and 5V backplane designs, and its interrupt logic surfaces card-presence changes to the shelf manager without polling.
Recommandé
ATCA / AdvancedTCA Shelf Manager Arbitration
The PCA9541APW/01 is well suited for ATCA shelf managers because it natively supports the dual-redundant IPMB (Intelligent Platform Management Bus) topology that AdvancedTCA mandates. The /01 variant's channel-0 pre-selection aligns with the ATCA convention of designating IPMB-A as the primary bus, eliminating firmware-side startup races. Its integrated INT0/INT1 outputs let the shelf controller log which IPMB channel is currently active, supporting event auditing and failover diagnostics. The device operates across the full industrial temperature range (-40C to +85C) required for telecom central-office deployments.
Recommandé
RAID Storage Controllers with Dual-BMC Redundancy
RAID storage controllers commonly use two baseboard management controllers (BMCs) for high availability, and the PCA9541APW/01 cleanly arbitrates which BMC owns the I2C-attached peripherals (EEPROMs, sensors, FRU ID). The /01 variant guarantees that the designated primary BMC is on the bus at power-up, avoiding race conditions during boot. Its fast-mode 400 kHz I2C capability keeps sensor polling latency low even with many downstream devices. Compared to a discrete FET-based arbitration circuit, the PCA9541APW/01 eliminates race-condition firmware workarounds and provides built-in interrupt feedback for BMC health monitoring.
Recommandé
Industrial PLC Systems with Dual CPU Arbitration
Industrial PLCs that use two CPUs (one real-time control, one supervisory) for fault tolerance benefit from the PCA9541APW/01's clean master-arbitration behavior. Its automatic activity-failover logic frees the supervisory CPU from handshaking overhead, and the active-low RESET pin lets a watchdog force deterministic channel re-selection after a CPU lockup. Industrial-temperature-grade operation (-40C to +85C) and the TSSOP package's compatibility with conformal coating make it suitable for factory-floor environments with vibration and humidity exposure.
Recommandé
Fault-Tolerant Medical Device Controllers
Medical device controllers (infusion pumps, patient monitors, imaging subsystems) increasingly use dual-processor architectures for safety compliance, and the PCA9541APW/01 provides hardware-level master arbitration that complements software safety checks. Its deterministic /01 channel-0 pre-selection avoids firmware-race conditions at startup - critical for IEC 62304-compliant designs. The integrated INT0/INT1 outputs let the supervisory processor log master-control events for post-market surveillance, while the RESET pin enables deterministic recovery from master-side faults.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour PCA9541APW/01 — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | PCA9541APW/03 | PCA9541APW/01,118 | PCA9541APW/01,112 | PCA9541APW,112 | PCA9541APW,118 |
|---|---|---|---|---|---|---|
| Package | 16-pin TSSOP (SOT403-1) | 16-pin TSSOP (SOT403-1) - same | 16-pin TSSOP (SOT403-1) - same | 16-pin TSSOP (SOT403-1) - same | 16-pin TSSOP (SOT403-1) - same | 16-pin TSSOP (SOT403-1) - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Function | 2-to-1 I2C master selector | 2-to-1 I2C master selector | 2-to-1 I2C master selector | 2-to-1 I2C master selector | 2-to-1 I2C master selector | 2-to-1 I2C master selector |
| Startup Channel Selection | Channel 0 pre-selected | No channel pre-selected | Channel 0 pre-selected | Channel 0 pre-selected | Firmware-controlled (no /01 or /03) | Firmware-controlled (no /01 or /03) |
| Supply Voltage Range | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V |
| I2C Bus Modes | Standard-mode, Fast-mode | Standard-mode, Fast-mode | Standard-mode, Fast-mode | Standard-mode, Fast-mode | Standard-mode, Fast-mode | Standard-mode, Fast-mode |
| Operating Temperature Range | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Packaging Format | Tube (suffix 112) / Reel (suffix 118) | Tube or Tape & Reel | Tape & Reel | Tube | Tube | Tape & Reel |
Principaux différenciateurs
- Native dual-master arbitration (not a multiplexer) (vs TCA9548A (TI 1-to-8 channel I2C switch))
- Channel 0 pre-selected at startup for deterministic power-on behavior (vs PCA9541APW/03)
- Bidirectional interrupt logic with separate INT0 and INT1 outputs (vs PCA9541APW/03)
- Integrated active-low RESET for deterministic recovery (vs Discrete FET-based arbitration circuits)
Notes de conception
Decouple VCC (pin 16) with a 100 nF X7R ceramic capacitor placed within 5 mm of the supply pin, plus a 1 uF bulk capacitor on the upstream supply rail. The PCA9541APW/01 draws very low quiescent current but its pass-gate switches can inject transient currents into VCC during channel transitions; the 100 nF cap absorbs these spikes. Per the NXP PCA9541A datasheet, hold RESET low for at least the specified minimum duration after VCC reaches 90% of nominal to guarantee deterministic channel selection.
Place pull-up resistors on the active upstream channel (SCL0/SDA0 or SCL1/SDA1) and on the downstream SCL/SDA bus. The PCA9541APW/01 pass gates do not include internal pull-ups, and pull-up values must follow the I2C-bus specification for the chosen mode (typically 4.7 kohm for Standard-mode at 5V and 10 kohm for Fast-mode). Estimate: at 400 kHz with 10 kohm pull-ups and 100 pF bus capacitance, the rise time is approximately 1 microsecond - within the Fast-mode 300 ns target only if total capacitance is kept below 50 pF.
Do not leave RESET floating - tie it to VCC through a 10 kohm resistor if no external reset controller is used. A floating RESET pin can pick up noise and cause unintended channel resets during EMI events. Avoid placing the PCA9541APW/01 near switching-power-supply switch nodes; while it has good noise immunity, the SCL/SDA traces are high-impedance and can couple switching noise into the bus. Use guard traces or ground fills around the downstream I2C traces in noisy environments.
The downstream SCL/SDA traces must be kept short and matched in length to within 10 mm to preserve I2C signal symmetry. At Fast-mode 400 kHz, even small impedance mismatches between SCL and SDA can shift duty cycle and cause the master to mis-sample data. Per the NXP PCA9541A datasheet, downstream bus capacitance must stay below the standard I2C limit of 400 pF; when designing multi-device downstream trees, sum the individual device pin capacitances plus trace capacitance to ensure compliance.
Informations de conformité
RoHS and REACH compliant per NXP product page. Lead-free and halogen-free per datasheet. AEC-Q100 not applicable - this is an industrial/commercial interface IC, not an automotive-grade part.
