Diodes Incorporated PI7C8958AFHE

Overview

PI7C8958AFHE from Diodes Incorporated is an obsolete PCI-to-serial octal UART bridge IC with eight independent 16C550-compatible channels, 64-byte transmit/receive FIFOs per channel, and integrated PCI interface logic supporting 32-bit/33 MHz operation. It operates from a 25 MHz crystal input and supports programmable baud rates up to 1.5 Mbps per channel in enhanced 950 mode. Used in industrial PC add-in cards for legacy RS-232/422/485 multi-port serial expansion.

For engineers reviewing the PI7C8958AFHE datasheet, PI7C8958AFHE pinout, PI7C8958AFHE application, or PI7C8958AFHE equivalent, key selection considerations include PCI bus timing compliance, per-channel FIFO depth and trigger level configurability, automated XON/XOFF flow control support, and register-level compatibility with standard 16550/16C550 drivers.

Technical Context

The PI7C8958AFHE implements a PCI-compliant configuration space (Class Code 0700h - Serial Controller) alongside eight independent UART cores sharing a common 25 MHz clock source and internal prescaler. Each UART supports I/O-mapped and memory-mapped register access modes, selectable via hardware strap or EEPROM configuration.

It features three operational UART modes: standard 450/550 (16-byte FIFO), enhanced 550 (64-byte FIFO with programmable trigger levels), and enhanced 950 (64-byte FIFO with automatic flow control, special character detection, and global interrupt aggregation). Baud rate generation uses a 16× oversampling architecture with divisor latch registers and sample clock tuning.

Key Specifications

Pinout & Package

PI7C8958AFHE is housed in a 128-pin TQFP (14 mm × 14 mm, 0.4 mm pitch) package with exposed thermal pad. Pin assignments are defined per Section 4 of DS40304 Rev 4-2, including dedicated PCI bus signals (AD[31:0], C/BE[3:0]#, PAR, FRAME#, TRDY#, IRDY#), UART I/Os (TxD/RxD for each of 8 channels), and configuration strapping pins (MODE[1:0], CLKSEL).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal UART bridge applications.

Compared with PI7C8958AFHE, XR17V358 offers future-proof PCIe connectivity but demands hardware redesign, while XR16L788 retains PCI compatibility at the cost of boot-time reconfiguration and reduced interrupt management efficiency.

Availability

PI7C8958AFHE is available at Aetrix Electronics and suitable for industrial PC expansion, POS terminal integration, medical data logging, and automated test equipment requiring stable component supply despite its obsolete status.

Supply support for PI7C8958AFHE 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 analog ICs, headquartered in California, with design, manufacturing, and distribution operations across Asia and the Americas.

The PI7C8958AFHE belongs to Diodes' legacy PCI interface product line, designed specifically to extend serial connectivity in x86-based industrial and commercial systems requiring multi-port RS-232/422/485 expansion with minimal CPU overhead.

FAQ

Is PI7C8958AFHE pin-compatible with earlier PI7C8958 variants?

Yes - PI7C8958AFHE is a Pb-free, halogen-free variant in TQFP-128 packaging and maintains identical pinout and electrical characteristics with prior versions like PI7C8958AE. The 'FHE' suffix denotes RoHS-compliant packaging; no functional or mechanical changes affect PCB layout or schematic design.

Does PI7C8958AFHE support Linux kernel drivers out of the box?

Yes - it is supported by the standard '8250_pci' driver in Linux kernels ≥2.6.32. Kernel detects it as a PCI device with Class Code 0700h and auto-probes UART ports using standard 16550 register offsets. No vendor-specific driver is required for basic operation.

Can PI7C8958AFHE operate without an external crystal?

No - the device requires a 25 MHz fundamental-mode crystal connected to X1/X2 pins. Internal oscillator circuitry is not self-contained; no internal RC oscillator or clock input bypass mode is provided per datasheet Section 5.2.11.

What is the maximum sustained data rate across all eight channels?

At 1.5 Mbps per channel (Enhanced 950 mode), total theoretical bandwidth is 12 Mbps. Real-world sustained throughput is limited by PCI bus arbitration and host DMA efficiency; measured performance shows >9.2 Mbps aggregate with optimized Linux driver and scatter-gather DMA enabled.