BUF20800/20820EVM Hardware Overview
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summarizes the function of the BUF20800/20820EVM board jumpers. For most application,
Jumpers 2 through 5 are all set to the default positions.
Table 3. BUF20800/20820EVM Test Board Jumper Functions
Jumper
Default
Purpose
JMP1
INT
This jumper selects whether the DV
DD
digital supply pin on the
BUF20800 or BUF20820 is connected to the V
DUT
signal
generated from the USB_DIG_Platform or whether DV
DD
is
connected to terminal T2 to allow for an external supply to power
the digital circuitry. The default INT position connects the DV
DD
pin to the V
DUT
control signal
JMP2
INT
This jumper selects whether the SCL pin on the BU20800 or
BUF20820 is connected to the I2C_SCK_ISO signal generated
from the USB_DIG_Platform or whether the SCL pin is
connected to terminal T4 to allow for an external source to
control the I
2
C clock line. The default INT position connects the
SCL pin to the I2C_SCK_ISO control signal.
JMP3
INT
This jumper selects whether the SDA pin on the BUF20800 or
BUF20820 is connected to the I2C_SDA_ISO signal generated
from the USB_DIG_Platform or whether the SDA pin is
connected to terminal T4 to allow for an external source to
control the I
2
C data line. The default INT position connects the
SDA pin to the I2C_SDA_ISO control signal.
JMP4
INT
This jumper selects whether the LD pin on the BUF20800 or
BUF20820 is connected to jumper JMP5 or whether the LD pin
is connected to terminal T3 to allow for an external source to
control the latch pin. The default INT position connects the LD
pin to jumper JMP5.
JMP5
L
This jumper selection depends on the configuration of JMP4. In
the event that JMP4 is set to INT, JMP5 is used to select
whether or not the LD pin on the BUF20800 or BUF20820 is
connected to the DV
DD
digital supply or whether the LD pin is
connected to ground. The default LOW position connects the LD
pin to ground. If JMP4 is set to the EXT position, JMP4 is not
used.
JMP6
0
This jumper selects the I
2
C A0 address selection. Two separate
I
2
C addresses can be selected depending on whether JMP6 is
set high or low.
JMP7
INT
This jumper selects whether or not the RefH pin on the
BUF20800 is connected or BUF20820 to the AV
DD
signal
generated by the external analog power-supply input at terminal
T1, or whether the RefH pin is connected to a user-designated
reference, which is set using an external input at terminal T5 as
well as resistors R1 and R2. The default INT position connects
the RefH pin to the external power-supply input at terminal T1.
JMP8
INT
This jumper selects whether or not the RefL pin on the
BUF20800 is connected to ground or whether the RefL pin is
connected to a user-designated reference, which is set using an
external input at terminal T5 as well as resistors R3 and R4. The
default INT position connects the RefL pin to ground.
12
BUF20800/20820EVM User Guide and Software Tutorial
SBOU100 – April 2011
© 2011, Texas Instruments Incorporated