Microchip Technology MCP2122T-E/SNG

Overview

MCP2122T-E/SNG from Microchip Technology is an IrDA® 1.3-compliant infrared encoder/decoder IC that bridges UART-based host controllers to IR optical transceivers. It supports up to 115.2 Kbaud, operates from 1.8V to 5.5V, features 16XCLK-synchronized timing, delivers 1.63 µs TXIR pulse width at full rate, and maintains 2 µA low-power mode at 1.8V/125°C - deployed in embedded diagnostics, firmware updates, and portable data exchange systems.

For engineers reviewing the MCP2122T-E/SNG datasheet, MCP2122T-E/SNG pinout, MCP2122T-E/SNG application, or MCP2122T-E/SNG equivalent, key selection criteria include IrDA 1.3 physical layer compliance, UART-to-IR bit-level encoding/decoding capability, 8-pin SOIC package compatibility with HSDL-7000, extended temperature support (–40°C to +125°C), and 16XCLK-driven baud rate derivation.

Technical Context

The MCP2122T-E/SNG implements a dedicated IrDA 1.3 physical layer encoder/decoder with no protocol stack - it performs real-time UART-to-IrDA modulation (TX) and IrDA-to-UART demodulation (RX) using a single external 16XCLK input. Its internal logic enforces strict 16-bit-clock-per-bit timing, pulse-width-limited TXIR output (≤4 µs high time), and Schmitt-triggered inputs for noise immunity.

Operation requires synchronous baud rates between UART and IR interfaces, determined solely by the 16XCLK frequency (e.g., 1.8432 MHz for 115.2 Kbaud). The device operates in half-duplex mode, disables TXIR during RXIR activity, and enters ultra-low-power state (<2 µA) when RESET is held low - with no internal oscillator or voltage regulator.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (E/SNG), 150 mil width, Pb-free, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar infrared encoder/decoder applications.

Compared with MCP2120-I/P and TUSB3410, the MCP2122T-E/SNG uniquely balances SOIC footprint compatibility with HSDL-7000, 16XCLK timing control for deterministic baud derivation, and sub-2 µA reset-state power - making it optimal for space-constrained, battery-aware, and automotive-qualified embedded IR interfaces.

Availability

MCP2122T-E/SNG is available at Aetrix Electronics and suitable for industrial diagnostics, portable medical device firmware updates, and manufacturing configuration systems requiring stable component supply, long-term lifecycle assurance, and extended temperature performance.

Supply support for MCP2122T-E/SNG 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

Microchip Technology is a leading provider of microcontroller, analog, FPGA, and connectivity solutions, serving automotive, industrial, consumer, and communications markets with silicon, development tools, and support infrastructure.

The MCP2122T-E/SNG belongs to Microchip's IrDA encoder/decoder product line, designed specifically to simplify reliable, standards-compliant infrared communication in resource-constrained embedded systems without requiring host CPU intervention for physical layer processing.

FAQ

What is the maximum supported baud rate for MCP2122T-E/SNG and how is it determined?

The MCP2122T-E/SNG supports a maximum baud rate of 115.2 Kbaud, strictly determined by the frequency of the external 16XCLK signal - specifically, F_16XCLK = 16 × desired baud rate. For 115.2 Kbaud, a 1.8432 MHz 16XCLK input is required. This relationship is fixed and non-programmable; the device does not support independent UART and IR baud rates.

Is MCP2122T-E/SNG pin-compatible with the Agilent HSDL-7000, and what does that mean for PCB design?

Yes, MCP2122T-E/SNG is fully pinout-compatible with the Agilent HSDL-7000 - meaning identical pin numbering, function mapping, electrical characteristics, and SOIC-8 footprint. This allows direct replacement in existing HSDL-7000 designs without PCB layout changes, solder mask updates, or netlist modifications - significantly reducing redesign effort and requalification time.

How does the MCP2122T-E/SNG achieve its 2 µA low-power mode, and what conditions must be met?

The MCP2122T-E/SNG achieves 2 µA standby current by asserting the RESET pin low, which disables the internal state machine and halts all logic activity. To reach this spec, VDD must be 1.8V and ambient temperature +125°C; additionally, 16XCLK must be inactive and all inputs (TX, RXIR) held at valid logic levels - no external clock or signal activity is permitted during this state.

Does MCP2122T-E/SNG support full-duplex communication between UART and IR interfaces?

No, MCP2122T-E/SNG operates exclusively in half-duplex mode: it cannot transmit and receive simultaneously. When RXIR detects an incoming IR pulse (low), the TXIR output is automatically disabled to prevent collision. Similarly, TXIR activity inhibits RXIR sampling - enforcing strict transmit-or-receive arbitration at the physical layer.

What is the role of the 16XCLK pin, and can it be gated during idle periods to save power?

The 16XCLK pin provides the master timing reference for all encoding/decoding operations - each bit is resolved over exactly 16 clock cycles. Yes, 16XCLK can be stopped (gated) when the system is not expecting IR traffic; doing so reduces dynamic power consumption. However, 16XCLK must be stable and running before releasing RESET or initiating communication.