Diodes Incorporated PI7C9X1172BZHEX

Overview

PI7C9X1172BZHEX from Diodes Incorporated is a dual-channel, full-duplex UART bridge controller supporting I²C-bus or SPI host interface, 64-byte TX/RX FIFOs per channel, programmable baud rates up to 16 Mbit/s (4× sampling), and RS-485/RS-232/IrDA protocol bridging in industrial embedded systems.

For engineers reviewing the PI7C9X1172BZHEX datasheet, PI7C9X1172BZHEX pinout, PI7C9X1172BZHEX application, or PI7C9X1172BZHEX equivalent, key selection criteria include dual UART channel independence, hardware/software flow control implementation, GPIO pin mapping, RS-485 auto-direction control via EN485#, and I²C/SPI interface select logic on pin 32.

Technical Context

The PI7C9X1172BZHEX implements two independent UART cores with fully compatible 16C450 register sets, each supporting fractional baud rate generation, 5–8-bit character formatting, and 1/1.5/2 stop bits. It integrates dedicated hardware for Auto-RTS/CTS flow control with configurable trigger levels stored in TCR and FCR registers.

Its dual-interface architecture allows runtime selection between I²C (fast-mode, 400 kHz) and SPI (slave mode only, 33 MHz max clock), with interface mode determined by the logic level on I2C/SPI# (pin 32). RS-485 half-duplex direction control is implemented via RTS output and EN485# pin sampling at power-up.

Key Specifications

Pinout & Package

PI7C9X1172BZHEX is available in 32-pin QFN (5 × 5 mm, 0.5 mm pitch) and 28-pin TSSOP packages. The QFN variant includes an exposed thermal pad (soldered to PCB ground plane) for enhanced thermal performance in compact, battery-powered designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SC16IS752IPW and MAX3107EAE+T, PI7C9X1172BZHEX uniquely delivers dual UARTs with integrated RS-485 direction control, IrDA encoding/decoding, and eight GPIOs - reducing system-level component count and firmware complexity in multi-protocol edge devices.

Availability

PI7C9X1172BZHEX is available at Aetrix Electronics and suitable for industrial computing, factory automation, and battery-operated embedded systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for PI7C9X1172BZHEX 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, specializing in high-performance, energy-efficient solutions for industrial, computing, and consumer markets.

The PI7C9X1172 belongs to Diodes' high-integration UART bridge controller product line, designed specifically for protocol translation between modern host interfaces (I²C/SPI) and legacy serial standards (RS-232/RS-485/IrDA) in space-constrained, low-power embedded systems.

FAQ

What host interface modes does PI7C9X1172BZHEX support, and how is mode selected?

The PI7C9X1172BZHEX supports I²C-bus (fast-mode, 400 kHz) and SPI (slave mode 0, up to 33 MHz) host interfaces. Mode selection is controlled by the logic level on pin 32 (I2C/SPI#): HIGH selects I²C mode (with SDA as bidirectional open-drain I/O), LOW selects SPI mode (with SO as three-state output and SI as input). This configuration is sampled at power-up and cannot be changed dynamically.

How does RS-485 auto-direction control work on PI7C9X1172BZHEX?

RS-485 auto-direction is enabled by pulling EN485# (pin 19) LOW at power-up. In this mode, the RTSB# output automatically toggles to control the RS-485 transceiver's direction pin: asserted during transmission, deasserted during reception. No external logic or MCU timing is required, and the behavior is synchronized with UART transmit/receive state machines.

Can both UART channels operate simultaneously with different protocols (e.g., one RS-232, one RS-485)?

Yes - each UART channel (A and B) has independent control signals (RTSA#/RTSB#, CTSA#/CTSB#, EN485# is shared but applies only to RTSB# in default configuration). Channel A can drive an RS-232 transceiver while Channel B drives an RS-485 transceiver with auto-direction, provided EN485# is configured appropriately and GPIOs are assigned to distinct peripheral control functions.

What is the role of the Trigger Level Register (TLR) versus the FIFO Control Register (FCR) for interrupt generation?

The TLR provides programmable RX/TX FIFO trigger levels (0–63 bytes), while the FCR offers fixed selectable levels (1, 4, 8, or 14 bytes). If any TLR bit is set, the TLR value overrides the FCR setting for that FIFO. After reset, FCR defaults are used. This dual-layer control allows fine-grained interrupt tuning for latency-sensitive applications without sacrificing compatibility with legacy 16C450 software.