Microchip Technology MCP2122-E/PG

Overview

MCP2122-E/PG from Microchip Technology is an IrDA® 1.3-compliant infrared encoder/decoder IC that bridges UART-based host controllers to infrared 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 and +125°C - deployed in embedded system diagnostics and firmware update links.

For engineers reviewing the MCP2122-E/PG datasheet, MCP2122-E/PG pinout, MCP2122-E/PG application, or MCP2122-E/PG equivalent, this page delivers verified electrical specs, IrDA physical layer timing constraints, UART-to-IR signal translation behavior, reset and clock interface design guidance, and validated drop-in alternatives for industrial IR communication designs.

Technical Context

The MCP2122-E/PG implements a fixed-ratio, non-programmable IrDA 1.3 encoder/decoder with synchronous 16XCLK-driven bit timing - no internal oscillator, no baud rate register, and no IrCOMM protocol stack. Its RXIR/TXIR interface strictly follows the 1.63 µs (115.2 Kbaud) to 19.53 µs (9600 baud) pulse-width encoding scheme defined in the IrDA Physical Layer v1.3 specification.

It requires external 16XCLK input (DC to 1.8432 MHz), supports Schmitt-trigger inputs on TX, RXIR, RESET, and 16XCLK, and enforces half-duplex operation: simultaneous transmit/receive is prohibited by hardware state machine design. The device enters known-reset state on RESET low and disables all outputs except RX (driven low) and TXIR (forced low).

Key Specifications

Pinout & Package

Package: 8-pin PDIP (Plastic Dual In-line Package), lead-free, through-hole mount - compatible with standard DIP sockets and wave-soldered industrial control boards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HSDL-7000, MCP2122-E/PG adds RoHS compliance and extended temperature support; compared with MCP2120-I/P, it trades higher baud capability for smaller package, reset control, and 16XCLK flexibility - making it optimal for cost-sensitive, thermally demanding, or reset-critical IR interfaces.

Availability

MCP2122-E/PG is available at Aetrix Electronics and suitable for industrial diagnostics, medical device commissioning, and factory-floor configuration requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for MCP2122-E/PG 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 Inc. is a leading provider of microcontroller, analog, and connectivity solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The MCP2122-E/PG belongs to Microchip's IrDA encoder/decoder product line, designed specifically to simplify reliable, standards-compliant infrared communication in resource-constrained embedded systems - targeting diagnostics, configuration, and firmware update use cases.

FAQ

What is the function of the 16XCLK pin on the MCP2122-E/PG?

The 16XCLK pin on the MCP2122-E/PG serves as the external bit clock input that drives all internal timing functions. It must be supplied with a stable square wave (DC to 1.8432 MHz), where exactly 16 edges correspond to one UART bit period. This synchronous clock ensures precise IrDA-compliant encoding and decoding - unlike internal oscillator-based alternatives, the MCP2122-E/PG relies entirely on this external source for timing accuracy and jitter control.

Does the MCP2122-E/PG support full-duplex UART communication?

No, the MCP2122-E/PG does not support full-duplex UART communication. Its architecture enforces strict half-duplex operation because the IR interface can only transmit or receive at any given time - the internal state machine prevents simultaneous TXIR assertion and RXIR sampling. When RXIR detects an incoming IR pulse, TXIR is automatically disabled, and vice versa. This constraint is inherent to the MCP2122-E/PG design and aligns with IrDA Physical Layer v1.3 requirements.

What is the minimum pulse width supported by the MCP2122-E/PG at 115.2 Kbaud?

At 115.2 Kbaud, the MCP2122-E/PG supports a minimum TXIR pulse width of 1.63 µs - matching the IrDA Physical Layer v1.3 specification's minimum detectable pulse width. This value is fixed by the 16XCLK timing structure (16 edges per bit) and is confirmed in Table 2-4 of the DS21894C datasheet. The device achieves this precisely without external adjustment, ensuring compatibility with certified IrDA transceivers such as the Vishay TFDU4300.

How does the MCP2122-E/PG enter low-power mode, and what is the typical current draw?

The MCP2122-E/PG enters low-power mode when the RESET pin is driven low - disabling the internal state machine and forcing TXIR and RX to known states. At 1.8V and +125°C, the device draws just 2 µA in this mode, as specified in D020 of the DS21894C datasheet. To achieve minimum current, ensure 16XCLK is inactive and all inputs (TX, RXIR) are held static at valid logic levels. This mode is ideal for battery-powered field service tools that spend extended periods idle between IR sessions.

Is the MCP2122-E/PG pin-compatible with the Agilent HSDL-7000?

Yes, the MCP2122-E/PG is explicitly designed to be pinout-compatible with the Agilent HSDL-7000 infrared encoder/decoder. Both devices share identical 8-pin PDIP/SOIC footprints and matching pin assignments (e.g., Pin 1 = 16XCLK, Pin 2 = TX, Pin 3 = RX, etc.). This compatibility allows direct replacement in existing HSDL-7000-based designs without layout changes - though designers must verify voltage, temperature, and RoHS requirements, as the MCP2122-E/PG adds 1.8V support and extended temperature range.