MCP2036 Microchip Technology, MCP2036 Datasheet - Page 3

• Manufacturer Part Number: MCP2036
• Description: Inductive Sensor Analog Front End Device
• Manufacturer: Microchip Technology

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FIGURE 1-2:
The coil voltages are then multiplexed into the
Synchronous Detector section by the LBTN/LREF
multiplexer. This allows the microcontroller to select
which signal is sampled by the detector. The detector
converts the coil voltages into a DC level using a
frequency mixer, amplifier, and filter.
The mixer is composed of two switches driven by the
clock present on the CLK signal input. The switches
toggle the amplifier/filter between an inverting and
non-inverting topology, at a rate equal to the clock input
frequency. This inverts and amplifies the negative side
of the signal, while amplifying the positive side. The
result is a pulsed DC signal with a peak voltage,
proportional to the amplitude of the AC coil voltage.
© 2009 Microchip Technology Inc.
Key Coils
MCP2036 Typical Application
LREF
CD4052
0
1
2
3
1
3
0
2
10nF
10nF
10Ω
I/O
I/O
I/O
I/O
LBTN
REFSEL
PIC
DRVOUT
LREF
CS
The gain of the detector is set by two pairs of resistors;
one pair are the internal fixed series resistors between
the frequency mixer and the amplifier. The second
resistor pair are the two external gain set resistors
(R
the external gain setting resistors form a low pass filter
which converts the pulsed DC output signal into a
smooth DC voltage which is proportional to the AC
sensor voltage input. The output of the system is
present on the V
microcontroller’s ADC input for conversion into a digital
value.
The virtual ground reference for the detector/amplifier
is generated by a second internal op amp which
produces a virtual ground equal to ½ the supply
voltage. The virtual ground is available externally at the
V
detector circuit, allowing single supply operation. A
small external capacitance is required to stabilize this
output and limit noise.
REF
®
MCP2036
GAIN
Microcontroller
). The two capacitors (C
output and used internally throughout the
V
DETOUT
V
V
DRVIN
PWM
V
ADC
DET-
DET+
CLK
REF
DETOUT
C
C
R
FILTER
R
R
FILTER
IN
GAIN
GAIN
C
MCP2036
ADC
pin, which drives the
FILTER
C
IN
DS22186A-page 3
) in parallel with
R
C
ADC
RGND