MCP2036 Inductive Sensor Analog Front End Device Features: Description: Complete Inductance Measurement System: The MCP2036 Inductive Sensor Analog Front End (AFE) combines all the necessary analog functions for - Low-Impedance Current Driver a complete inductance measurement system. - Sensor/Reference Coil Multiplexer The device includes: - High-Frequency Detector Operating Voltage: 2.7 to 5.5V High-frequency, current-mode coil driver for exciting the sensor coil. Low-Power Standby Mode Synchronous detector for converting AC sense Gain and Frequency set by external passive voltages into DC levels. components Output amplifier/filter to improve resolution and limit noise. Typical Applications: Virtual ground reference generator for single Harsh environment inductive keyboards supply operation. Inductive rotational sensor interface The device is available in 14-pin PDIP, SOIC and Inductive displacement sensor interface 16-pin QFN packages: Inductive force sensor interface Package Types MCP2036 14-pin PDIP, SOIC MCP2036 16-pin QFN V 1 14 V REF DET+ V LREF 2 13 DET- V LBTN 3 12 DETOUT LREF 1 12 V DET- V DD 4 11 V SS 2 LBTN 11 V DETOUT Reserved 5 10 DRVOUT V DD 3 10 V SS CS DRVIN 6 9 DRVOUT 4 9 Reserved CLK REFSEL 7 8 2009 Microchip Technology Inc. DS22186B-page 1 V 16 REF 5 DRVIN 15 NC CLK 6 14 NC REFSEL 7 V 13 DET+ CS 8MCP2036 The AC voltages generated across the coils, are then 1.0 FUNCTIONAL DESCRIPTION capacitively coupled into the LBTN and LREF inputs. The MCP2036 measures a sensor coils impedance by An input resistance of 2K between the inputs and the exciting the coil with a pulsed DC current and virtual ground offsets the AC input voltages up to the measuring the amplitude of the resulting AC voltage signal ground generated by the reference voltage waveform. The drive current is generated by the generator, as shown in Figure 1-1. on-chip current amplifier/driver which takes the high-frequency triangular waveform present on the DRVIN input, and amplifies it into the pulsed DC current for exciting the series combination of the sensor coils. LBTN LREF CLK Input MUX Op. Amp. Block V 1 0 DET+ REFSEL 10K + V DETOUT 10K V SS - Mixer V DET- V DD Key Inductor Driver Voltage V REF Reference DRVIN DRVOUT CS FIGURE 1-1: MCP2036 Block Diagram DS22186B-page 2 2009 Microchip Technology Inc.