Texas Instruments PGA450Q1EVM, User Manual

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TPIC1021AQDRQ1
RXD
1
EN
2
NWAKE
3
TXD
4
GND
5
LIN
6
VSUP
7
INH
8
U1
LIN TxD GND
LIN RxD
GND
V_LIN
V_LIN
GND
LIN EN
FOOTPRINT OK 4/21/10
B
A
V
3
0
0
4
W
-7
-F
D3
R5
1.0k,0603,1/10W,5%
C5
220pF,0603,50V,10%,X7R
R4
1.0k,0603,1/10W,5%
C4
0
.1
u
F
,0
8
0
5
,5
0
V
,1
0
%
,X
7
R
R3
0
,0
6
0
3
,1
/1
0
W
,5
%
NWAKE
R6
0
,0
6
0
3
,1
/1
0
W
,5
%
GND
5V 5V
V_LIN LIN
GND
GND
LIN
R
T
L
T
L
SEC
C
T
C
PT
C
TUNE
T T
TUNE PT
SEC
C L
C C
L
´
= -
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PGA450-Q1 Communication Interfaces
7 SLDU007C – March 2012 – Revised November 2015
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Copyright © 2012–2015, Texas Instruments Incorporated
PGA450Q1EVM User’s Guide
harsh environments, consider closed-top waterproof sensors, and inquire with distributors. The
distributors will then request an order with Murata. Lead times for these sensors may vary up to
several weeks.
Key ultrasonic sensor specifications are frequency, sensitivity, and directivity. The transformer is used to
excite the transducer. The transformer is center tapped to double the voltage. Typically, a tuning capacitor
is needed to match the resonant frequency between the transducer and transformer.
(1)
C
PT
, R
T
, L
T
, and C
T
are characteristics of the transducer, L
SEC
is the secondary inductance of the
transformer, and C
TUNE
is an external capacitor placed across the terminals of the transducer.
Figure 3. Equivalent Circuit of Transformer-Transducer Sensor Pair
7 PGA450-Q1 Communication Interfaces
The PGA450-Q1 device has several communication options including: SPI, LIN, and UART. All of these
communication interfaces and related circuitry are present on the PGA450Q1EVM.
7.1 SPI
SPI is the main communication method on the PGA450-Q1 device. The 8051W inside the device must be
put in reset to communicate using SPI. The SPI signals can be monitored with the CS, SCLK, SDI, and
SDO test points on the EVM.
7.2 LIN
The EVM includes a LIN transceiver, which is the master transceiver. The PGA450-Q1 device is always a
slave on the LIN bus and has the slave transceiver integrated inside the device.
Figure 4. LIN Master Transceiver
The 5-V supply in Figure 4 is provided by the USB communication board.