EM6420 – Interface IC for capacitive touch sensors

The EM6420 from EM Microelectronic is an ultra-low-power interface IC for capacitive touch sensors. The device sequentially detects up to 16 capacitive sensor inputs and makes detected touch events available to a host microcontroller.

This makes the EM6420 suitable for compact, battery-powered user interfaces in mobile devices, sensors, smart devices, industrial electronics, and wireless IoT systems.

Capacitive Touch Interface for Embedded Devices

The EM6420 is designed for applications in which mechanical buttons are to be replaced by capacitive touch surfaces. This enables robust, sealed, and easy-to-clean product designs, such as in portable devices, household appliances, lighting controls, keyboards, toys, or compact HMI solutions.

In wirelessly networked devices, the EM6420 serves as the interface between touch surfaces and the host microcontroller. Touch inputs can be captured locally and then processed in systems using BLE, NFC, RFID, LPWAN, or other wireless technologies. Typical functions include activation, pairing, mode selection, operation confirmation, or slider functions.

Up to 16 Sensor Inputs

The IC supports up to 16 analog sensor inputs per device. For more than 16 touch surfaces, multiple EM6420s can be used in parallel. Configurable parameters include the number of sensors, scan frequency, sensitivity, and IRQ condition.

Detected touch events are signaled via an IRQ output. The host microcontroller can then read the sensor status via the selected communication interface. Additionally, when sensor areas are located close together, the EM6420 can detect the sensor with the strongest activation.

Flexible Host Interfaces

For host connectivity, the EM6420 supports 4-wire SPI, I²C, a 4-bit parallel interface, and an 8-bit direct output mode. This allows the device to be integrated into both microcontroller-based designs and simple standalone architectures.

The communication interface is selected via configuration inputs. The host acts as the master, and the EM6420 as the slave. The device uses the IRQ signal to indicate that a defined state or a touch event has occurred.

Ultra-Low-Power Operation

The EM6420 supports two supply voltage ranges: 1.2 to 2.0 V and 2.2 to 3.6 V. In ultra-low-power mode, typical current consumption is 2.0 µA at 3.0 V for 16 sensors with an 8 Hz scan frequency. For 8 sensors with a 2 Hz scan frequency, typical current consumption is specified as 0.7 µA at 3.0 V.

This makes the IC suitable for battery-powered devices where touch inputs must be continuously monitored. In Disable Mode, the current consumption drops to a few nanoamperes, which supports systems with long idle periods.