BU21079F-E2

Overview

The BU21079F-E2 is a capacitive switch controller IC designed for operating switches with low power consumption via intermittent operation mode. It features an Analog Front End (AFE), A/D converter, MPU, and a 2-wire serial bus interface compatible with the I2C protocol. The device supports simple switches, matrix switches (up to 16 switches using 4x4 sensors), and sliders. It includes automatic self-calibration to handle external noise and temperature drift. Operating voltage ranges from 3.0V to 5.5V, with an operating current of 2.5mA (typical) and an operating temperature range of -25°C to 85°C.

Feature Summary

• Supports simple switches, matrix switches, and slider configurations.
• Integrates automatic self-calibration for stability against noise and temperature drift.
• Features intermittent operation mode to reduce power consumption.
• Includes interrupt output capability to notify host of switch operations.

Applications

• Electronic devices with multiple switches
• Information appliances such as printers
• AV appliances such as digital TV and HDD recorders
• Notebook PCs
• Air-conditioners, refrigerators, and electrical rice cookers

Procurement Notes

Verify the component status before procurement, as the BU21079F-E2 may be listed as Not Recommended for New Designs (NRND). Confirm that the SOP-16 package dimensions and pinout match your PCB layout requirements. Ensure the host system supports the required 2-wire serial bus interface compatible with the I2C protocol for proper communication.

Selection Notes

Select this IC when designing systems requiring capacitive sensing for up to eight sensor ports configured as simple switches or matrix keys. Consider the intermittent operation mode if power efficiency is critical. Verify that the host microcontroller can handle the slave address 0x5C and process the interrupt signals generated by the INT port during switch state changes.

Part Context

The BU21079F-E2 belongs to ROHM Semiconductor's BU21079 series of capacitive switch controllers. It is part of a family of ICs designed to reduce host CPU load by integrating sensor data processing and application functions directly into the controller. This specific model utilizes an SOP-16 package and operates within a standard industrial temperature range.

Replacement Considerations

Check for direct pin-compatible replacements within the BU21079 series or other ROHM capacitive switch controllers. Verify that any substitute maintains the same 8-channel capacity, I2C interface compatibility, and power supply requirements to ensure seamless integration without redesigning the host interface circuitry.

FAQ

How does the BU21079F-E2 handle external noise?

The IC activates automatic self-calibration when it detects external noise or temperature drift to maintain stable detection performance.

What types of switch configurations are supported?

It supports simple switches, matrix switches (maximum 16 switches using 4x4 sensors), and slider inputs.

How is the host notified of switch operations?

An interrupt signal is sent from the INT port to the host whenever a register is updated due to detected switch operations such as touch, release, or hold.