NXP Semiconductors PCA9618UKZ

Overview

The PCA9618UKZ from NXP Semiconductors is a single-channel Fast-mode Plus (Fm+) I²C-bus repeater IC that provides bidirectional buffering between two I²C bus segments, supports 0 Hz to 1 MHz operation, enables up to 540 pF capacitance per side at 1 MHz, features 2.2 V to 5.5 V supply range, and delivers latching-free operation with overvoltage-tolerant DATAA/DATAB pins - used in high-density sensor hubs and multi-board industrial control systems requiring bus segmentation.

For engineers reviewing the PCA9618UKZ datasheet, PCA9618UKZ pinout, PCA9618UKZ application, or PCA9618UKZ equivalent, this page delivers verified technical context on Fm+ repeater timing behavior, static offset voltage management between port A and port B, powered-off high-impedance I/O, and real-world design constraints for star vs. series bus topologies.

Technical Context

The PCA9618UKZ implements asymmetric voltage-level translation: port A uses a 0.35V_CC input threshold and drives a hard LOW (~0.1 V), while port B employs a 0.45 V input threshold and outputs a controlled LOW (~0.55 V) to prevent latching. Its internal glitch filter ensures stable 46 ns minimum propagation delay across temperature and supply voltage.

It supports Standard-mode, Fast-mode, and Fast-mode Plus I²C-bus devices, SMBus (standard and high-power modes), and PMBus, with open-drain I/Os requiring external pull-up resistors on both sides. The device remains high-impedance when unpowered (V_CC = 0 V), and its power-up circuit disables output drivers until V_CC exceeds 2.2 V and internal references settle (~400 µs).

Key Specifications

Pinout & Package

PCA9618UKZ is housed in a WLCSP4 wafer-level chip-scale package (0.78 × 0.83 × 0.53 mm), with 4 solder bumps arranged in a 2×2 grid. The package requires reflow soldering only; wave soldering is not supported. Moisture sensitivity level (MSL) compliance must be observed per packing label.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9617A and TCA9617A, the PCA9618UKZ uniquely combines latching-free offset design, 1 MHz Fm+ support, and ultra-low quiescent current (<3 mA) - making it optimal for space-constrained, high-speed, single-channel isolation where reliability under voltage mismatch is critical.

Availability

PCA9618UKZ is available at Aetrix Electronics and suitable for industrial sensor hubs, multi-board server management systems, and automotive body control modules requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9618UKZ 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 PCA9618UKZ belongs to NXP's I²C-bus repeater product line, engineered specifically to solve bus capacitance overload and timing compliance issues in modular, multi-node embedded systems using Fast-mode Plus and SMBus protocols.

FAQ

What is the primary function of the PCA9618UKZ in an I²C system?

The PCA9618UKZ functions as a single-channel bidirectional I²C-bus repeater that isolates capacitance between two bus segments, extends reach up to 540 pF at 1 MHz, prevents latching through asymmetric port voltage design, and provides deterministic propagation delay to meet SMBus hold-time requirements. It does not act as a level shifter for logic families outside I²C voltage ranges, nor does it add protocol intelligence - the PCA9618UKZ strictly preserves I²C timing and signaling integrity across segmented buses.

Can the PCA9618UKZ be used in a star topology with multiple devices?

Yes, multiple PCA9618UKZ units can be configured in a star topology by connecting all port A pins to a common bus and routing individual port B pins to separate slave clusters. This configuration is explicitly supported in the datasheet and maintains signal integrity because port A has no static offset and can be safely wired in parallel. Each PCA9618UKZ still requires its own V_CC and GND connections, and pull-up resistors must be present on both sides of every unit - the PCA9618UKZ itself does not drive or terminate the shared port A bus.

Does the PCA9618UKZ support SMBus high-power mode?

Yes, the PCA9618UKZ accommodates SMBus high-power mode devices as confirmed in Section 6.1 of the datasheet, which states compatibility with "SMBus (standard and high power mode), PMBus and multiple masters." Its 13 mA sink capability on port B at 2.2 V and 30 mA capability at 5 V aligns with SMBus high-power mode drive requirements, and its 0.55 V VOL ensures proper LOW-level recognition by high-power SMBus slaves expecting V_IL ≤ 0.4 V.

How does the PCA9618UKZ prevent latching during bus contention?

The PCA9618UKZ prevents latching via deliberate voltage offset engineering: port B outputs a LOW at ~0.55 V, while its input threshold is set at 0.45 V - creating a 100 mV guard band so the output LOW is not recognized as a valid input LOW. Simultaneously, port A uses a 0.35V_CC threshold and drives a hard ~0.1 V LOW. This asymmetry ensures neither port sustains a self-reinforcing feedback loop - a condition rigorously validated per JEDEC JESD78 latch-up testing (>100 mA).

Is the PCA9618UKZ compatible with 1-Wire bus systems?

Yes, the PCA9618UKZ can buffer 1-Wire bus signals as stated in the General Description: "The PCA9618 can also be used as a buffer on a 1-wire bus similar to how the PCA9617A is used for the I2C-bus." Its open-drain I/O structure, 5.5 V tolerance, and bidirectional operation match 1-Wire electrical requirements. However, it provides no protocol awareness - timing-critical 1-Wire reset pulses and presence detection must still be managed by the host controller; the PCA9618UKZ only extends physical layer reach and isolates capacitance.