Diodes Incorporated PI3C3861Q

Overview

PI3C3861Q from Pericom Semiconductor is a 10-bit, 2-port, low-ON-resistance (5 Ω) bus switch operating at 2.5 V or 3.3 V supply, with rail-to-rail signal switching, 5 V I/O tolerance, and >400 MHz bandwidth. It enables hot-insertion in high-speed data routing between two bidirectional buses (A0–A9 and B0–B9), used in PCIe add-in card docking and memory expansion subsystems.

For engineers reviewing the PI3C3861Q datasheet, PI3C3861Q pinout, PI3C3861Q application, or PI3C3861Q equivalent, key selection criteria include ON-resistance matching, propagation delay (<0.25 ns), BE-controlled enable timing (tPZH/tPHZ), 5 V I/O tolerance, and QSOP-24 thermal and layout compatibility.

Technical Context

The PI3C3861Q implements a passive FET-based analog bus switch architecture with no internal logic or level-shifting circuitry-signal path integrity is preserved via direct A↔B conduction when BE is LOW. Its 5 Ω R_ON and 10 pF C_ON yield sub-0.25 ns RC time constant under 50 pF load, ensuring negligible added delay beyond driver/load interaction.

BE is an active-low control that places all 10 channels into high-impedance state when HIGH, enabling hot-plug isolation. The device supports dual-supply domain interoperability: 2.5 V/3.3 V core operation with 5 V-tolerant I/O pins, eliminating external clamping for mixed-voltage backplane interfaces.

Key Specifications

Pinout & Package

PI3C3861Q is housed in a 24-pin QSOP (150-mil width), RoHS-compliant and Pb-free capable, with standard JEDEC MO-137AC footprint and 0.635 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3384CDW, PI3C3861Q adds 5 V I/O tolerance and guaranteed hot-insertion behavior; versus PI3CHD3224QE, it offers QSOP-24 compatibility and lower unit cost where 12-bit width and ±8 kV ESD are not mandatory.

Availability

PI3C3861Q is available at Aetrix Electronics and suitable for PCIe docking, DDR2 memory expansion, USB 2.0 hub multiplexing, and modular test equipment requiring stable component supply and long-term obsolescence management.

Supply support for PI3C3861Q 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

Pericom Semiconductor (now part of Diodes Incorporated) specialized in high-speed interface solutions, including clock buffers, USB/PCIe switches, and signal integrity components for computing and communications infrastructure.

The PI3C3861 belongs to Pericom's high-bandwidth analog bus switch product line, designed specifically for hot-pluggable, low-latency data routing in compute expansion and modular system architectures.

FAQ

What is the maximum recommended capacitive load for PI3C3861Q to maintain <0.25 ns propagation delay?

The 0.25 ns propagation delay specification assumes a 50 pF load capacitance and 500 Ω termination. At higher loads (e.g., >75 pF), RC delay increases linearly-measured t_PLH/t_PHL rises to ~0.35 ns at 100 pF. Layout best practices recommend minimizing trace capacitance and using controlled-impedance routing to stay within spec.

Can PI3C3861Q operate with V_CC = 2.5 V while interfacing to 3.3 V signals on A/B pins?

Yes. The device supports rail-to-rail switching and 5 V I/O tolerance, so 3.3 V signals applied to A/B pins are safely clamped and passed through with no level shifting when V_CC = 2.5 V. This enables mixed-voltage backplane designs without external translators.

Is BE pin compatible with 1.8 V logic controllers?

No. BE is referenced to V_CC, with V_IL = 0.8 V max and V_IH = 2.0 V min at V_CC = 3.3 V. A 1.8 V controller cannot reliably drive BE-level-shifting (e.g., TXB0108) or a 3.3 V-compatible GPIO is required for proper enable/disable control.

Does PI3C3861Q require external pull-up or pull-down resistors on A/B pins?

No. The A/B pins are fully passive and exhibit no static current draw. External biasing is unnecessary unless system-level termination or fail-safe idle-state definition is required. Internal ESD protection diodes do not affect DC biasing requirements.