Diodes Incorporated PI7C9X7954BFDE

Overview

PI7C9X7954BFDE from Diodes Incorporated is a PCI Express® 2.0-compliant quad UART bridge IC with integrated PCIe endpoint logic, four independent UART channels supporting up to 15 Mbps baud rate, 128-byte TX/RX FIFOs per channel, and 128-pin LQFP package. It enables legacy serial peripheral connectivity in modern PCIe-based industrial controllers and embedded computing platforms.

For engineers reviewing the PI7C9X7954BFDE datasheet, PI7C9X7954BFDE pinout, PI7C9X7954BFDE application, or PI7C9X7954BFDE equivalent, key selection criteria include PCIe 2.0 x1 link compliance, UART register compatibility with 16550/16750, FIFO depth configuration, EEPROM-based configuration storage, and industrial temperature support (–40°C to +85°C).

Technical Context

The PI7C9X7954BFDE implements a PCIe 2.0 endpoint with configurable BARs and MSI interrupt support, mapping PCIe TLPs to internal register space for UART control and status access. Its UART subsystem supports 5–9 data bits, 1–2 stop bits, parity modes, and hardware/software flow control per channel.

It integrates a programmable baud rate generator with fractional divider, clock prescaler (÷1 to ÷16), and selectable clock sources including external crystal (14.7456 MHz) or PCIe REFCLK. Power management includes D0–D3hot states and wake-on-RX capability via WAKEUP_L pin.

Key Specifications

Pinout & Package

Package: 128-pin LQFP (14 mm × 14 mm, 0.4 mm pitch), thermally enhanced with exposed pad (EPAD) connected to GND for improved thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PCIe-to-quad-UART bridge applications.

Compared with XR17V354IL-F and PI7C9X7952B, the PI7C9X7954BFDE delivers higher serial throughput (15 vs. 10 Mbps), deeper FIFOs (128 vs. 64 bytes), built-in configuration EEPROM, and full industrial temperature support-making it the sole option meeting demanding embedded PCIe serial gateway requirements.

Availability

PI7C9X7954BFDE is available at Aetrix Electronics and suitable for industrial PLC serial gateways, medical diagnostic equipment interfaces, ruggedized transportation telematics, and test & measurement rack controllers requiring stable component supply across multi-year production cycles.

Supply support for PI7C9X7954BFDE 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and integrated circuits, headquartered in California, with design, manufacturing, and distribution operations spanning Asia, Europe, and North America.

The PI7C9X7954BFDE belongs to Diodes' PCI Express bridge IC product line, engineered specifically to extend legacy serial communication into modern high-speed PCIe infrastructure for industrial automation, healthcare, and transportation systems.

FAQ

Does PI7C9X7954BFDE require an external crystal oscillator?

Yes - the device supports either a 14.7456 MHz fundamental-mode crystal connected between CLKINP and CLKINN pins, or an external 100 MHz differential PCIe REFCLK. The crystal option enables standalone operation without dependency on host PCIe clock, critical for systems where REFCLK may be unstable or absent during initialization.

Can PI7C9X7954BFDE operate in legacy PCI mode?

No - the PI7C9X7954BFDE is a PCIe-only device and does not support conventional PCI or PCI-X protocols. It lacks PCI bus signals (AD[31:0], C/BE#, FRAME#, IRDY#, etc.) and contains no PCI configuration space compatibility layer; it implements only PCIe Base Specification 2.0 endpoint functionality.

What UART register compatibility does PI7C9X7954BFDE provide?

The device implements full 16550A and 16750 register compatibility, including LCR bit[5:0] for word length/stop bits/parity, MCR bit[5] for loopback, and EFR bit[4] for enhanced feature enable. All UART registers are memory-mapped within PCIe BAR space and accessible via standard PCIe memory read/write transactions.

Is GPIO[7:0] configurable as interrupt sources?

No - GPIO[7:0] pins are software-configurable as inputs or outputs only; they do not generate interrupts. Interrupts are generated exclusively by UART events (RX/TX FIFO status, line status changes) and PCIe events (MSI, PME), with GPIO state readable via GPIO Control Register (offset D8h) but no associated interrupt capability.