NXP Semiconductors PCA9540BDP/DG,118

Overview

PCA9540BDP/DG,118 from NXP Semiconductors is a 1-of-2 bidirectional I²C-bus translating multiplexer in TSSOP8 package, enabling selective routing of SCL/SDA signals to either SC0/SD0 or SC1/SD1 channel. It supports voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses, features 5 V-tolerant I/O, operates from 2.3 V to 5.5 V supply, and delivers ≤31 Ω ON-state resistance at 3.6 V. It is used in multi-voltage sensor hub architectures where isolated I²C bus segmentation is required.

For engineers reviewing the PCA9540BDP/DG,118 datasheet, PCA9540BDP/DG,118 pinout, PCA9540BDP/DG,118 application, or PCA9540BDP/DG,118 equivalent, this device serves as a critical bus isolation and level-shifting component in mixed-voltage embedded systems-particularly where hot insertion, low standby current (<1 µA), and glitch-free power-up behavior are mandatory.

Technical Context

The PCA9540BDP/DG,118 implements a single-pole double-throw (SPDT) analog switch architecture controlled via I²C write to an 8-bit register, where only bits B2–B0 determine channel selection (0x04 = channel 0, 0x05 = channel 1). Its pass-gate design uses VDD as a clamping reference to limit Vo(sw), enabling true bidirectional voltage translation without external level shifters.

It integrates internal power-on reset (POR) that initializes all registers to zero and deselects both channels, ensuring no false START/STOP conditions during power ramp. The I²C interface complies with SMBus standards and supports standard-mode (100 kHz) and fast-mode (400 kHz) clock frequencies with built-in input filtering for noise immunity.

Key Specifications

Pinout & Package

TSSOP8 package (SOT505-1): plastic thin shrink small outline, 8 leads, 3 mm body width, 0.65 mm lead pitch, exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9544APWR and PCA9542ADP,118, the PCA9540BDP/DG,118 uniquely balances dual-channel selectivity, integrated voltage translation, and ultra-low standby current-making it optimal for space-constrained, mixed-voltage embedded systems where bus isolation and power efficiency are co-prioritized.

Availability

PCA9540BDP/DG,118 is available at Aetrix Electronics and suitable for server baseboard management, industrial sensor hubs, and automotive ADAS modules requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.

Supply support for PCA9540BDP/DG,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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with leadership in interface, power management, and embedded processing technologies.

The PCA9540B family was designed specifically to solve I²C bus contention and voltage-domain interoperability challenges in dense, multi-peripheral embedded systems-delivering reliable, low-power, and software-configurable bus segmentation.

FAQ

What is the primary function of the PCA9540BDP/DG,118?

The PCA9540BDP/DG,118 is a 1-of-2 bidirectional I²C-bus multiplexer that selectively routes upstream SCL/SDA signals to either SC0/SD0 or SC1/SD1 downstream channel. Its core function is bus segmentation with integrated voltage translation, enabling a single I²C master to manage peripherals operating at different logic levels (1.8 V, 2.5 V, 3.3 V, 5 V) without external level shifters. This capability is implemented via VDD-referenced pass gates and programmable register control.

Does the PCA9540BDP/DG,118 support hot insertion of downstream I²C devices?

Yes, the PCA9540BDP/DG,118 explicitly supports hot insertion as stated in its official features list. Its architecture ensures that unselected channels are fully isolated-both electrically and logically-from the active bus path. When a downstream device is connected or disconnected while the other channel is active, no current leakage, bus contention, or false START/STOP generation occurs. This behavior is validated under I²C-bus electrical specifications and confirmed in NXP's AN262 application note.

What is the maximum I²C clock frequency supported by the PCA9540BDP/DG,118?

The PCA9540BDP/DG,118 supports I²C clock frequencies up to 400 kHz, compliant with Fast-mode I²C specifications. This is confirmed in Table 9 (Dynamic Characteristics) of the datasheet, which specifies fSCL = 0–400 kHz for Fast-mode operation. Propagation delay is limited to 0.3 ns, ensuring timing margins are preserved even at maximum speed. No derating is required for standard-mode (100 kHz) or Fast-mode use within its specified supply and temperature ranges.

How does the PCA9540BDP/DG,118 achieve voltage level translation between different I²C buses?

The PCA9540BDP/DG,118 achieves voltage translation through its VDD-referenced pass-gate structure: Vo(sw), the maximum output voltage seen at SCx/SDx terminals, is clamped by the VDD supply voltage. For example, setting VDD = 3.3 V limits Vo(sw) to ≤2.8 V, allowing safe interfacing with 2.7 V or 3.3 V downstream devices-even when upstream pull-ups are at 5 V. External pull-up resistors on each SCx/SDx pair set the final bus voltage, while the device's 5 V-tolerant inputs accept signals up to 7 V.

What happens to the PCA9540BDP/DG,118 channels during power-up?

During power-up, the PCA9540BDP/DG,118 executes an internal Power-On Reset (POR) that holds the device in reset until VDD reaches VPOR (1.6–2.1 V). Upon release, all registers initialize to zero-deselecting both channels-and the I²C-bus state machine resets to idle. This guarantees no channel is active at startup, eliminating risk of bus contention or unintended peripheral access. The POR behavior is hardware-enforced and requires VDD to drop below 0.2 V for ≥5 µs to retrigger.