MCP2030T-IST View Datasheet(PDF) - Microchip Technology
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MCP2030T-IST Datasheet PDF : 66 Pages
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MCP2030
4.2 Application Examples
Figure 4-2 shows an example of an external circuit for
a bidirectional communication transponder application.
Each LC input pin is connected to an external LC
resonant circuit. To achieve the best performance, the
resonant frequency of the LC circuit needs to be
matched to the detecting carrier frequency of interest.
The resonant frequency is given by the following
equation:
fo
=
--------1----------
2π LC
In typical 125 kHz applications, the L value is a few mH,
and the C value is a few hundred pF, for example,
L = 4.9 mH, and C = 331 pF.
The resonant frequency can be fine-tuned by program-
ming the internal tuning capacitors.
The output of the MCP2030 is fed into the external
MCU. The external MCU can send data by clamping on
and clamping off the MCP2030 coil voltages using an
SPI command, or via a UHF transmitter.
The RSSI output of the MCP2030 can be digitized by
the MCU firmware. Users can also consider using a
MCU that has an internal analog-to-digital converter
(ADC) such as the PIC16F684 or a stand-alone ADC
device.
Figure 4-3 shows an example of a hands-free Passive
Keyless Entry (PKE) system. The base station unit
transmits an LF command. The MCP2030 detects the
base station command and feeds the detected output
to the external MCU (PIC16F636). If the command is
correct, the MCU responds via an external UHF
transmitter or by using the LF talk-back modulators of
the MCP2030 device.
Figure 4-4 shows an example when the device is used
for a tire pressure monitoring sensor application. The
device detects the LF Initiator commands and transmits
the tire pressure data to the base station via an external
UHF transmitter.
SW1
SW2
SW3
SW4
PIC16F636/684
MCP2030
VSS
VSS
CS
LCCOM
SCLK/ALERT
NC
To ADC RSSI
LCX
NC
LCY
LFDATA/CCLK/SDIO LCZ
+3V
VDD
VDD
C
+3V
air-core
L coil
C
ferrite-core
coil
L
C
L
ferrite-core coil
315/434 MHz
RF Circuitry
(UHF TX)
FIGURE 4-2: Example of External Circuits for Bidirectional Communication Transponder Applications.
DS21981A-page 28
© 2005 Microchip Technology Inc.
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