Diodes Incorporated PI7C9X1172CZHE

Overview

PI7C9X1172 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, baud rates up to 16 Mbit/s (4× sampling), and RS-485/RS-232/IrDA protocol bridging. It operates at 1.8 V/2.5 V/3.3 V and targets embedded industrial gateways requiring low-power serial expansion.

For engineers reviewing the PI7C9X1172 datasheet, PI7C9X1172 pinout, PI7C9X1172 application, or PI7C9X1172 equivalent, key selection criteria include dual UART channel independence, programmable hardware/software flow control, auto RS-485 direction control via RTS#, IrDA SIR support up to 1.152 Mbps, and GPIO flexibility for system-level signal management.

Technical Context

The PI7C9X1172 implements two independent UART cores with fully compatible 16C450 register mapping, enabling drop-in firmware reuse. Each channel supports fractional baud rate generation with divisor range 1–(2¹⁶−1) and configurable character formatting (5–8 bit, parity, stop bits).

It integrates dual interface modes: I²C-bus slave only (fast-mode, 400 kHz) and SPI slave (mode 0, up to 33 MHz), with interface selection controlled by the dedicated I2C/SPI# pin. RS-485 half-duplex operation is enabled via EN485# and managed automatically using RTS# output polarity inversion.

Key Specifications

Pinout & Package

Available in 32-pin QFN (5 mm × 5 mm, 0.5 mm pitch) and 28-pin TSSOP packages. Both variants feature exposed thermal pad (QFN) or standard leadframe (TSSOP), with identical pin functionality across packages except for pin count and layout.

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 dual UARTs, dual interface support (I²C/SPI), hardware RS-485 direction control, and IrDA SIR - making it optimal for space-constrained, multi-protocol embedded systems needing flexible host connectivity.

Availability

PI7C9X1172 is available at Aetrix Electronics and suitable for industrial PLC gateways, smart meter communication hubs, handheld barcode scanners, and medical device serial adapters requiring stable component supply across extended temperature ranges (−40 °C to +85 °C).

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' serial interface bridge product line, designed specifically to simplify host-to-peripheral UART expansion in resource-constrained embedded systems with mixed voltage and protocol requirements.

FAQ

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

The PI7C9X1172 supports I²C-bus (fast-mode, slave-only) and SPI (mode 0, slave-only) interfaces. Mode selection is controlled by the dedicated I2C/SPI# pin: HIGH configures I²C operation (with SDA bidirectional, SCL input), while LOW enables SPI (with SO output, SI input, SCLK input, CS# input). The pin state is latched at power-up and cannot be changed dynamically.

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

Automatic RS-485 direction control is enabled by pulling EN485# LOW at power-up. In this mode, the RTS# output becomes an inverted driver enable signal synchronized to UART transmission - asserted before TX starts and deasserted after the final stop bit. No external logic or firmware timing is required, and the behavior is fully hardware-managed per channel.

Can the PI7C9X1172 operate with a 1.8 V host interface while driving 3.3 V RS-485 transceivers?

Yes. The PI7C9X1172 supports 1.62 V to 3.63 V VDD operation and has level-tolerant I/Os. Its TXA/TXB outputs swing rail-to-rail within VDD, and its RTS#/CTS# signals are compatible with 3.3 V transceiver control inputs when VDD = 1.8 V, provided external pull-ups match the transceiver's logic threshold (e.g., 3.3 V pull-up with current-limiting resistor).

Does the PI7C9X1172 support simultaneous use of both UART channels with independent configurations?

Yes. Each UART channel (A and B) has fully independent configuration registers for baud rate, data format (bits/parity/stop), FIFO trigger levels, flow control settings, and modem control. Register access is channel-selectable via the channel select bits in the configuration registers, enabling concurrent, asymmetric operation - e.g., Channel A at 921.6 kbps (8N1), Channel B at 115.2 kbps (7E2).