Diodes Incorporated PI7C9X7958ANBE

Overview

PI7C9X7958ANBE from Pericom Semiconductor is a PCI Express® 2.0-compliant octal UART controller with eight independent asynchronous serial channels, integrated PCIe endpoint logic, 128-byte TX/RX FIFOs per channel, programmable baud rates up to 15 Mbps, and support for RS-232/422/485 transceivers in industrial communication gateways.

For engineers reviewing the PI7C9X7958ANBE datasheet, PI7C9X7958ANBE pinout, PI7C9X7958ANBE application, or PI7C9X7958ANBE equivalent, key selection criteria include PCIe 2.0 x1 link compliance, per-channel FIFO depth and flow control, UART register compatibility with 16550A/16750, EEPROM-based configuration persistence, and LFBGA-160 package thermal performance in embedded server I/O expansion.

Technical Context

The PI7C9X7958ANBE implements a PCIe 2.0 endpoint with configurable BARs (Base Address Registers) and MSI interrupt support, enabling direct memory-mapped I/O access without host CPU polling. It integrates eight independent UART cores sharing a single 25 MHz or 14.7456 MHz crystal oscillator input, each supporting 5–8 data bits, 1–2 stop bits, and parity options.

Each UART channel supports hardware flow control (RTS/CTS), automatic XON/XOFF generation, internal loopback testing, and enhanced modes including 450/550/950-compatible register mapping. The device uses a dedicated EEPROM interface (SR_DO/SR_DI) for persistent configuration storage of vendor ID, subsystem ID, and UART initialization parameters.

Key Specifications

Pinout & Package

PI7C9X7958ANBE is housed in a 12 mm × 12 mm, 0.8 mm pitch 160-pin Low-Profile Fine-Pitch Ball Grid Array (LFBGA) package with exposed thermal pad for enhanced heat dissipation in sustained I/O workloads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal UART with PCIe interface applications.

Compared with XR17V358 and XR17V838, the PI7C9X7958ANBE offers proven industrial temperature reliability, simpler two-wire EEPROM integration, and native PCIe wake signaling - making it optimal for cost-sensitive, thermally demanding, or legacy driver-dependent deployments.

Availability

PI7C9X7958ANBE is available at Aetrix Electronics and suitable for industrial serial gateways, embedded server management cards, medical data loggers, and test & measurement rack controllers requiring stable component supply and long-term lifecycle support.

Supply support for PI7C9X7958ANBE 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 was a fabless provider of high-performance interface, timing, and signal integrity solutions, acquired by Diodes Incorporated in 2016; its legacy products remain widely deployed in industrial and communications infrastructure.

The PI7C9X7958ANBE belongs to Pericom's PCI Express bridge and serial interface product line, designed specifically to replace legacy ISA/PCI UART add-in cards with PCIe-native, multi-channel serial I/O for embedded computing platforms.

FAQ

Does PI7C9X7958ANBE require an external crystal oscillator?

Yes - it requires a 25 MHz or 14.7456 MHz fundamental-mode crystal connected to CLKINP/CLKINN pins. The internal PLL generates all UART baud clocks and PCIe reference timing; no external clock generator IC is needed, but crystal load capacitance must match datasheet specifications (12 pF typical).

Can PI7C9X7958ANBE operate in both I/O-mapped and memory-mapped modes?

Yes - it supports both programming models. I/O mode uses standard IN/OUT instructions with port addresses assigned via BAR0; memory-mapped mode uses MMIO addressing via BAR1. Mode selection is controlled by the DRIVER_SEL pin at power-on, and register layout differs slightly between modes per datasheet Sections 7.1 and 7.2.

What is the function of the RREF pin on PI7C9X7958ANBE?

RREF is a precision 1.2 V reference output used to bias external RS-232 transceiver charge pumps (e.g., MAX3232). It provides a stable, low-noise voltage source independent of VCC, ensuring consistent driver output swing across temperature and supply variation - critical for reliable long-cable RS-232 operation.

Is EEPROM configuration mandatory for PI7C9X7958ANBE operation?

No - EEPROM is optional. If no EEPROM is present, the device boots with default configuration: vendor ID = 0x12D8, device ID = 0x7958, and all UARTs disabled. Basic functionality (e.g., PCIe enumeration) works without EEPROM, but persistent settings like subsystem ID, GPIO defaults, and UART enablement require it.