MCP2036 Microchip Technology, MCP2036 Datasheet - Page 8

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

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MCP2036
FIGURE 3-2:
3.1
Figure 3-3
Touch keyboard with key controlled by the IO pins of
the PIC
FIGURE 3-3:
The PIC
wave signal and to do all the necessary operations for
proper detection of the key press event.
Then, R
the PWM into a quasi-triangular waveform.
To calculate the amplitude of the triangular signal, the
standard charging time equation for an RC network will
be used, as shown in
EQUATION 3-1:
For the first half of the square wave, the capacitor C
is charged through R
discharged through R
signal has a 50% duty cycle factor, we can consider:
DS22186A-page 8
®
Key Coils
IN
®
Application example
MCU.
-C
microcontroller is used to generate a square
shows an example for a 4-key Inductive
V t ( )
IN
filter converts the square wave output of
=
V
step
Equation
Using GPIO for Key Selection (Example)
MCP2036 Typical Application
IN
IN
•
LREF
[
, for the second half, it is
, and assuming that clock
1
–
CD4052
exp
0
1
2
3
1
3-1:
0
2
3
10nF
– (
t RC
⁄
)
]
10nF
10Ω
IN
I/O
I/O
I/O
I/O
PIC
LBTN
REFSEL
LREF
DRVOUT
CS
EQUATION 3-2:
®
MCP2036
Microcontroller
V
DETOUT
V
DRVIN
V
PWM
V
ADC
DET-
DET+
CLK
REF
V
V
start
stop
=
=
C
C
R
© 2009 Microchip Technology Inc.
FILTER
R
R
FILTER
V
V
IN
GAIN
GAIN
DD
DD
C
ADC
2 ⁄ +ΔV
2 ⁄ -ΔV
C
IN
R
C
ADC
RGND