Texas Instruments PCA9545ADGVR

Overview

PCA9545ADGVR from Texas Instruments is a low-voltage 4-channel I²C and SMBus switch with interrupt logic and reset functionality. It functions as a bidirectional translating multiplexer, enabling one master to selectively route SCL/SDA signals to four independent downstream I²C buses (SC0/SD0–SC3/SD3), supports voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V domains, and features four active-low interrupt inputs (INT3–INT0) with a shared active-low open-drain INT output. It is used in server backplanes to isolate temperature sensor clusters sharing identical I²C addresses.

For engineers reviewing the PCA9545ADGVR datasheet, PCA9545ADGVR pinout, PCA9545ADGVR application, or PCA9545ADGVR equivalent, key selection criteria include its 2.3 V to 5.5 V operating supply range, 400-kHz Fast-Mode I²C compatibility, 5.5-V tolerant I/Os, programmable channel selection via an 8-bit control register, and active-low RESET for bus-fault recovery - all critical for multi-sensor I²C arbitration in space-constrained industrial controllers.

Technical Context

The PCA9545ADGVR implements four independent bidirectional pass-gate switches controlled by an I²C-accessible 8-bit register, where bits B0–B3 select channels and bits B4–B7 reflect real-time interrupt status from each downstream bus. Its interrupt logic performs a wired-AND of INT3–INT0 onto the single INT output, allowing centralized interrupt detection without polling.

Each SCn/SDn channel uses voltage-limited pass gates referenced to VCC, enabling level translation without external level shifters; pull-up resistors on each bus must be connected to their respective domain voltages (e.g., 3.3 V on master side, 1.8 V on slave side). The device incorporates power-on reset (VPOR = 1.6–2.1 V) and a dedicated active-low RESET pin with 6-ns minimum pulse width for deterministic state machine recovery.

Key Specifications

Pinout & Package

TSSOP-20 package (6.50 mm × 4.40 mm), lead-free and RoHS-compliant, optimized for automated PCB assembly and thermal performance in dense layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C bus switching applications.

Compared with PCA9545ADGVR, TCA9545APWR offers enhanced robustness for field-deployed equipment, while PCA9544ADGVR provides a cost-optimized path for simpler topologies - both retain full software compatibility but differ in channel count and stress-handling capability.

Availability

PCA9545ADGVR is available at Aetrix Electronics and suitable for server backplane sensor management, rack-mounted telecom router monitoring, and factory automation PLC I/O expansion requiring stable component supply across multi-year production cycles.

Supply support for PCA9545ADGVR 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 company delivering analog and embedded processing solutions, with leadership in precision analog, power management, and interface technologies.

The PCA9545ADGVR belongs to TI's I²C switch and multiplexer product line, designed specifically to resolve I²C address conflicts and enable scalable sensor networks in space-constrained, mixed-voltage embedded systems.

FAQ

What is the maximum I²C clock frequency supported by the PCA9545ADGVR?

The PCA9545ADGVR supports I²C Standard-Mode up to 100 kHz and Fast-Mode up to 400 kHz. Its switching characteristics - including propagation delay (≤1 ns at CL = 15 pF) and rise/fall time compliance - are fully characterized across this range per JESD88 standards. This makes PCA9545ADGVR suitable for high-throughput sensor polling in real-time industrial control loops without introducing timing bottlenecks.

How does the PCA9545ADGVR handle I²C bus contention when multiple channels are enabled simultaneously?

The PCA9545ADGVR does not allow simultaneous channel activation in a way that creates electrical contention: its internal logic enforces exclusive channel selection - only one SCn/SDn pair is electrically connected to SCL/SDA at any time. Even if multiple bits B0–B3 are set in the control register, the device activates only the lowest-numbered enabled channel. This prevents bus collisions and ensures deterministic arbitration, a core design requirement validated in the PCA9545ADGVR's functional test suite.

Can the PCA9545ADGVR translate between 1.8-V and 5-V I²C buses without external components?

The PCA9545ADGVR enables voltage-level translation between 1.8-V and 5-V I²C domains using only external pull-up resistors - no additional level shifters are required. Its pass-gate architecture references the VCC supply, limiting the maximum passed voltage to VCC. Therefore, with VCC = 1.8 V, it safely interfaces 1.8-V slaves to a 5-V master by clamping SDA/SCL swing to 1.8 V on the slave side, while master-side pull-ups to 5 V maintain valid logic levels upstream. This capability is explicitly verified in TI's application note SBAA222.

What happens to the PCA9545ADGVR's channel state during a power-on reset?

During power-on reset, the PCA9545ADGVR initializes its internal control register to 0x00, deselecting all four channels (B0–B3 = 0) and clearing all interrupt flags (B4–B7 = 0). This default state is guaranteed once VCC rises above the power-on reset threshold VPOR (1.6–2.1 V). The device remains in reset until VCC stabilizes, ensuring no unintended channel activation occurs during power ramp - a behavior confirmed in the PCA9545ADGVR's production test flow and documented in section 9.4.2 of the datasheet.

Is the PCA9545ADGVR pin-compatible with the PCA9545A variant in TSSOP-20 packaging?

Yes, the PCA9545ADGVR is a direct pin-for-pin and functionally identical replacement for the base PCA9545A in TSSOP-20 (DGV) packaging. Both share identical pin numbering, electrical specifications, register map, and timing behavior. The "DGVR" suffix denotes TI's green, lead-free, tape-and-reel packaging variant - fully compliant with RoHS and JEDEC J-STD-020 moisture sensitivity Level 2a - with no impact on schematic or layout reuse.