Diodes Incorporated PI7C9X7958BNBE

Overview

PI7C9X7958BNBE from Diodes Incorporated is a PCI Express® 2.0-compliant octal UART IC with eight independent asynchronous serial channels, integrated PCIe endpoint logic, 128-byte TX/RX FIFOs per channel, and support for baud rates up to 15 Mbps. It operates from a single 3.3 V supply, features EEPROM configuration storage, and is used in server backplanes, industrial controllers, and embedded systems requiring high-density serial I/O expansion over PCIe.

For engineers reviewing the PI7C9X7958BNBE datasheet, PI7C9X7958BNBE pinout, PI7C9X7958BNBE application, or PI7C9X7958BNBE equivalent, this device delivers deterministic low-latency UART bridging with PCIe enumeration, hardware flow control (RTS/CTS), and configurable GPIOs - critical for legacy serial peripheral integration in modern x86 and ARM-based platforms.

Technical Context

The PI7C9X7958BNBE implements a PCIe Gen2 x1 endpoint with full configuration space compliance (PCI Local Bus Specification Rev 3.0), supporting both memory-mapped and I/O-mapped UART register access. Its UART core is compatible with 16C550/16C950 architecture, including enhanced features like automatic RTS/CTS flow control and fractional baud rate generation via programmable prescaler.

It integrates an on-die 25 MHz crystal oscillator input (or external clock), supports multiple operating modes (450/550/Enhanced 550/Enhanced 950), and includes dedicated registers for power management (D0–D3hot), MSI interrupt delivery, and EEPROM-based boot configuration - enabling stateless initialization without host driver intervention.

Key Specifications

Pinout & Package

The PI7C9X7958BNBE is housed in a 160-pin Low-Profile Fine-Pitch Ball Grid Array (LFBGA) package with 0.65 mm ball pitch and 9 mm × 9 mm body size. Thermal pad exposed on underside improves heat dissipation in sustained UART transmit operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XR17V358 and XR17V838, the PI7C9X7958BNBE uniquely balances Gen2 bandwidth, on-chip EEPROM configurability, and GPIO flexibility - making it optimal for fixed 8-port embedded systems where reliability, small footprint, and zero-touch deployment are prioritized.

Availability

PI7C9X7958BNBE is available at Aetrix Electronics and suitable for industrial automation, server management, medical diagnostics, and ruggedized field terminals requiring stable component supply and long-term lifecycle assurance.

Supply support for PI7C9X7958BNBE 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 semiconductor company specializing in discrete, analog, and mixed-signal ICs, with design centers in Asia, Europe, and the U.S., serving industrial, computing, and communications markets.

The PI7C9X7958BNBE belongs to Diodes' PCI Express interface product line, engineered specifically to simplify legacy serial peripheral integration into modern high-speed interconnect architectures while minimizing driver and firmware development effort.

FAQ

Does the PI7C9X7958BNBE require an external EEPROM to function?

No. The device operates with factory-default UART and PCIe configuration settings without EEPROM. However, an external SPI EEPROM (e.g., AT25DF041A) is required to store custom vendor IDs, subsystem information, or persistent UART parameter defaults across power cycles. The EEPROM interface is optional but recommended for production deployment.

Can the PI7C9X7958BNBE operate in legacy PCI mode?

No. The PI7C9X7958BNBE is a native PCIe 2.0 endpoint only and does not support parallel PCI bus signaling or legacy PCI configuration space. It requires a PCIe root complex or switch with standard PCIe enumeration capability - no PCI-to-PCIe bridge is supported or needed.

What is the maximum guaranteed baud rate with timing accuracy?

The device guarantees ±1.5% baud rate accuracy up to 15 Mbps when using the internal 25 MHz clock source with fractional divisor settings. At higher rates (e.g., 30 Mbps), accuracy degrades beyond specification due to integer division limitations in the baud rate generator - 15 Mbps is the validated maximum for compliant RS-422/485 operation.

How many GPIO pins are available, and can they be used as UART modem control signals?

The PI7C9X7958BNBE provides eight GPIO pins (GPIO[7:0]), each configurable via the GPIO Control Register (offset D8h). All eight can be individually assigned as RTS, CTS, DTR, DSR, DCD, or RI outputs/inputs - enabling full modem handshaking for all eight UART channels simultaneously without external logic.