Diodes Incorporated PI7C9X1172CLE

Overview

PI7C9X1172 from Diodes Incorporated is a dual-channel UART bridge controller that converts I²C-bus or SPI serial host interfaces to two independent full-duplex UART channels with 64-byte TX/RX FIFOs, supporting baud rates up to 16 Mbit/s (4× sampling) and IrDA SIR up to 1.152 Mbit/s, used in industrial computing and embedded RS-485/RS-232 interface bridging.

For engineers reviewing the PI7C9X1172 datasheet, PI7C9X1172 pinout, PI7C9X1172 application, or PI7C9X1172 equivalent, key selection criteria include dual UART channel count, I²C/SPI host interface flexibility, hardware/software flow control implementation, GPIO programmability, and RS-485 auto-direction control capability.

Technical Context

The PI7C9X1172 implements two independent UART cores with fully programmable character formatting (5–8 bit, parity, stop bits), fractional baud rate generation via 16-bit divisor, and register compatibility with industry-standard 16C450/16C550. Each UART supports separate RX/TX FIFO trigger level configuration and interrupt masking.

It integrates dual-mode interface selection (I²C slave only or SPI slave mode 0), on-chip crystal oscillator support (up to 24 MHz) or external clock input (up to 64 MHz), and eight user-programmable GPIO pins configurable as modem control signals (DSR/DTR/RI/CD) or general-purpose I/O via dedicated registers.

Key Specifications

Pinout & Package

Available in two RoHS-compliant, lead-free packages: 28-pin TSSOP (L) and 32-pin WQFN5050 (ZH). Both packages support identical pin functionality with minor layout differences; WQFN includes thermal pad for enhanced thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SC16IS752 and MAX3108, the PI7C9X1172 uniquely combines I²C/SPI dual-host support, RS-485 auto-direction, IrDA SIR, and eight GPIOs-making it optimal for compact, multi-protocol embedded gateways requiring minimal external components.

Availability

PI7C9X1172 is available at Aetrix Electronics and suitable for industrial automation, factory process control, and battery-operated handheld devices requiring stable component supply across extended temperature ranges (−40°C to +85°C) and long-term production continuity.

Supply support for PI7C9X1172 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 product line, designed specifically for embedded systems needing flexible host-to-serial protocol conversion with minimal external components and broad voltage/temperature support.

FAQ

What host interfaces does the PI7C9X1172 support, and how is the selection made?

The PI7C9X1172 supports both I²C-bus (fast-mode, up to 400 kHz) and SPI (mode 0, slave-only, up to 33 MHz) host interfaces. Selection is determined by the logic level on the I2C/SPI# pin at power-up: HIGH selects I²C mode, LOW selects SPI mode. In I²C mode, SDA and SCL are active; in SPI mode, SO, SI, SCLK, and CS# (A0) are used. The device does not support master-mode operation on either interface.

How does the PI7C9X1172 implement RS-485 half-duplex direction control?

The PI7C9X1172 uses the EN485# strap pin and RTS# output to enable automatic RS-485 direction control. When EN485# is pulled LOW at power-up, the RTS# signal drives the RS-485 transceiver's DE/RE pins directly-asserting during transmission and de-asserting when the TX FIFO empties. Polarity inversion is supported via register bit EN485_INV, allowing compatibility with both active-high and active-low transceivers without external logic.

Can the PI7C9X1172 operate with a 1.8 V supply, and what are the implications for I/O voltage levels?

Yes, the PI7C9X1172 operates from 1.62 V to 3.63 V, including 1.8 V nominal supply. All digital I/O pins (including UART TX/RX, GPIOs, and interface signals) are fully 1.8 V tolerant and internally level-shifted-no external level translators are needed when interfacing with 1.8 V microcontrollers. The device maintains full functionality, including 64-byte FIFO operation and interrupt generation, across the entire voltage range.

What UART register compatibility does the PI7C9X1172 provide, and how does it affect software porting?

The PI7C9X1172 implements a register map fully backward-compatible with the industry-standard 16C450 UART, including THRE, RDR, LCR, IER, IIR, FCR, and MCR registers. This allows existing 16C450 drivers to operate without modification-only minor initialization updates are needed for enhanced features like FIFO trigger levels or GPIO configuration. No register remapping or abstraction layer is required for basic UART functionality.