CH9121 - Ethernet converter chip - UART, TCP/IP, 2×UART, LQFP64

Description

The CH9121 integrates a 10/100M Ethernet controller (MAC + PHY) and a TCP/IP stack, enabling bidirectional, transparent data transmission between the network interface and the UART ports. The device supports four operating modes: TCP Client, TCP Server, UDP Client, and UDP Server, allowing for flexible configuration in industrial communication systems, automation, and IoT projects.

The network side supports 10/100 Mbps auto-negotiation, full/half duplex mode, and Auto MDI/MDIX. Available mechanisms include DHCP, DNS domain support, KEEPALIVE, and network parameter configuration via dedicated software or serial commands. Parameters are saved in internal memory and restored after a system restart.

The device provides two independent UART interfaces, enabling parallel data transmission. The supported data rate ranges from 300 bps to 921,600 bps, with a transmitter transmission error of less than 0.3%. Configurable parameters include 5/6/7/8 data bits, 1 or 2 stop bits, and parity (none, even, or odd). The UART interface operates in full- or half-duplex mode, with the ability to control the RS485 transmission direction (pins DIR1 and DIR2).

The CH9121 operates with a 3.3 V (VCC33) and 1.8 V (VCC18) power supply. The UART lines are compatible with 3.3 V and 5 V TTL levels. The device requires an external 30 MHz crystal oscillator. The LQFP64 package (10 x 10 mm) allows integration into compact PCB designs.

The default configuration includes TCP Client mode for port 1, an IP address of 192.168.1.200, a local port of 2000, and a UART speed of 9600 bps. Port 2 remains disabled by default.

The device is used in UART-to-Ethernet converters, remote access to microcontrollers, embedded systems, communication gateways, integration of industrial devices with LANs, and in projects requiring stable data transmission between the serial interface and the IP infrastructure.

Features

• Integrated 10/100M Ethernet MAC + PHY controller
• Supports 10/100 Mbps, full/half duplex, Auto MDI/MDIX
• Built-in TCP/IP stack
• Operating modes: TCP Client, TCP Server, UDP Client, UDP Server
• 2 independent UART interfaces
• UART speed: 300 bps – 921600 bps
• Configurable: 5/6/7/8 data bits, 1/2 stop bits, parity
• DHCP, DNS, and KEEPALIVE support
• Data buffering with configurable packet length (1–1024 bytes) and timeout
• RS485 transmission direction control (DIR1, DIR2)
• Power supply: 3.3 V (VCC33), 1.8 V (VCC18)
• UART interface compatible with 3.3 V and 5V TTL
• 30 MHz crystal oscillator required
• LQFP64 package, 10 × 10 mm
• Operating temperature range: –40°C to +85°C