Diodes Incorporated PI7C9X1172CZHEX

Overview

PI7C9X1172 from Diodes Incorporated is a dual-channel UART bridge controller supporting I²C-bus or SPI host interface, providing two full-duplex UARTs with 64-byte TX/RX FIFOs, 16 Mbps baud rate (4× sampling), and backward compatibility with 16C450/16C550 register sets. It operates across 1.8V–3.3V supply, supports RS-485 auto-direction control, IrDA SIR up to 1.152 Mbps, and integrates eight GPIOs - deployed in industrial computing and battery-powered embedded systems.

For engineers reviewing the PI7C9X1172 datasheet, PI7C9X1172 pinout, PI7C9X1172 application, or PI7C9X1172 equivalent, key selection criteria include dual UART channel independence, I²C/SPI interface selectability, hardware/software flow control implementation, RS-485 driver direction control via RTS, and GPIO mapping for DTR/DSR/CD/RI signaling in compact TSSOP-28 or WQFN-32 packages.

Technical Context

The PI7C9X1172 implements two independent UART channels sharing a single I²C or SPI host interface, with separate TX/RX FIFOs (64 bytes each) and programmable trigger levels per FIFO. Its register set mirrors the 16C450 architecture while extending functionality via Enhanced Feature Register (EFR) and Trigger Level Register (TLR).

Hardware flow control uses Auto-RTS and Auto-CTS with configurable halt/resume thresholds stored in the Transmission Control Register (TCR); software flow control supports dual Xon/Xoff characters with flexible detection logic (EFR[3:0] configuration). RS-485 half-duplex mode is enabled by EN485# pin, routing RTS# to driver direction control with polarity inversion support.

Key Specifications

Pinout & Package

PI7C9X1172 is available in two RoHS-compliant, lead-free packages: 28-pin TSSOP (L) and 32-pin WQFN5050 (ZH). The WQFN variant includes an exposed thermal pad (non-electrical, must be soldered to PCB ground plane for 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 MAX3109, the PI7C9X1172 uniquely combines I²C/SPI dual-interface support, RS-485 auto-direction, IrDA SIR, and eight GPIOs in a single compact package - enabling consolidated design for space-constrained industrial and portable systems without external glue logic.

Availability

PI7C9X1172 is available at Aetrix Electronics and suitable for industrial automation, embedded telemetry, and mobile point-of-sale terminals requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

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 analog, logic, and timing solutions for industrial, computing, and consumer markets.

The PI7C9X1172 belongs to Diodes' UART bridge controller product line, designed to simplify serial interface expansion in resource-constrained embedded systems where dual-channel protocol conversion, low-power operation, and compact footprint are essential.

FAQ

What interface modes does the PI7C9X1172 support, and how is mode selection implemented?

The PI7C9X1172 supports both I²C-bus (fast-mode, up to 400 kHz) and SPI (mode 0, slave-only, up to 33 MHz) host interfaces. Mode selection is controlled by the I2C/SPI# pin: HIGH configures I²C mode, LOW selects SPI mode. This signal is sampled at power-up and latched; changing it during operation has no effect. In I²C mode, A0/A1 set the 7-bit slave address; in SPI mode, A0 serves as CS# and A1 as SI.

How does the PI7C9X1172 implement RS-485 half-duplex direction control without external components?

The PI7C9X1172 uses the EN485# pin to enable RS-485 auto-direction mode. When EN485# is LOW at power-up, the RTS# output becomes the RS-485 driver direction control signal instead of a standard flow-control line. The device automatically asserts RTS# before transmitting and de-asserts it after transmission completes. An internal polarity inversion bit allows matching to either active-HIGH or active-LOW DE/RE requirements.

Can the PI7C9X1172's GPIO pins be used for modem control functions like DTR and DSR, and how are they configured?

Yes - GPIO0 through GPIO7 are fully configurable as modem control signals: GPIO0/DSRB#, GPIO1/DTRB#, GPIO2/CDB#, GPIO3/RIB#, GPIO4/DSRA#, GPIO5/DTRA#, GPIO6/CDA#, and GPIO7/RIA#. Configuration is done via the IODir (I/O Direction) and IOControl registers: setting a bit in IODir to '1' makes the corresponding pin an output (e.g., DTR), while '0' configures it as input (e.g., DSR). Pull-up/down resistors are not internal; external biasing is required for unused inputs.

What is the maximum achievable UART baud rate, and what clock source options support it?

The PI7C9X1172 supports UART baud rates up to 16 Mbps using 4× oversampling. This requires a clock source of at least 64 MHz - achievable via external clock input (up to 64 MHz) or crystal oscillator (up to 24 MHz) with internal PLL multiplication. The baud rate generator uses a 16-bit divisor; for example, a 64 MHz input yields 16 Mbps with divisor = 4. Lower rates (e.g., 115.2 kbps) are supported with 1.8384 MHz crystal or derived clocks.