AD7147ACPZ-1REEL

Overview

The AD7147ACPZ-1REEL is a CapTouch programmable controller for single-electrode capacitance sensors, manufactured by Analog Devices Inc. It integrates a 16-bit, 250 kHz sigma-delta capacitance-to-digital converter (CDC) with 13 sensor inputs. The device operates on a 2.6 V to 3.6 V supply and features an SPI-compatible serial interface. Key specifications include a typical update rate of 9 ms for all 13 inputs, femtofarad resolution, and low power consumption of 21.5 μA in low power mode. It includes on-chip automatic calibration logic and adaptive threshold levels to compensate for environmental changes.

Feature Summary

• Integrated 16-bit capacitance-to-digital converter with 13 sensor inputs
• SPI-compatible serial interface with separate VDRIVE level
• On-chip automatic calibration and adaptive threshold logic
• Low operating current: 1 mA full power, 21.5 μA low power mode

Applications

• Cell phones
• Personal music and multimedia players
• Smart handheld devices
• Television, A/V, and remote controls
• Gaming consoles

Procurement Notes

Verify the specific ordering suffix against the manufacturer's official documentation to confirm package type and reel quantity. Ensure compatibility with the host processor's SPI interface voltage levels using the VDRIVE pin. Confirm that the LFCSP-24 package requirements align with the PCB design guidelines provided in the datasheet.

Selection Notes

Select this component for applications requiring high-resolution capacitance sensing with minimal external components. The AD7147 supports single-electrode sensors, eliminating the need for external RC components. Consider the AD7147-1 variant if an I2C interface is required instead of SPI. Ensure the host processor can handle the required software algorithms for scroll bars or wheels if such functions are needed.

Part Context

The AD7147 belongs to the AD7147 series of CapTouch controllers designed for portable electronic devices. It is part of Analog Devices' portfolio for user input solutions, offering a complete capacitance sensing solution including sensor PCB footprint libraries. The device is qualified for automotive applications and operates within a temperature range of -40°C to +85°C.

Replacement Considerations

The AD7147-1ACPZ-RL is a compatible alternative with an I2C interface instead of SPI. Both parts share the same pinout and functionality except for the serial communication protocol. Verify register map compatibility, as the AD7147 register map is compatible with the AD7142.

FAQ

What is the maximum SCLK frequency for the SPI interface?

The maximum SCLK frequency for the AD7147 SPI interface is 5 MHz.

How does the AD7147 handle environmental changes?

The AD7147 features on-chip automatic calibration logic that performs continuous calibration at intervals when sensors are not touched, compensating for environmental factors like humidity and temperature.

What is the purpose of the ACSHIELD pin?

The ACSHIELD pin provides an active shield output to minimize noise pickup in the sensor. It outputs a 250 kHz oscillating signal and should be connected to an external shield or plane.