Datasheet

BUF22821EVM-USB Features www.ti.com
Table 5 summarizes the function of the USB_DIG_Platform jumpers. For most applications, the default
positions should be used. A separate document (SBOU058) provides details regarding the operation and
design of the USB_DIG_Platform.
Table 5. USB_DIG_Platform Jumper Functions
Jumper Default Purpose/Description
JUMP1 EXT This jumper selects external power or bus power.
External power is applied on J5 or T3 (up to +9 V
DC). Bus power is +5 V from the USB. External
power is typically used because the USB bus power
introduces additional noise.
JUMP2 EXT Same as JUMP1.
JUMP3 EE ON This jumper determines where the TUSB3210 loads
the USB_DIG_Platform firmware upon power-up or
reset. The EE Off position is used for development
or firmware update.
JUMP4, JUMP5 L, L This jumper sets the address for the
USB_DIG_Platform board. The only reason to
change from the default is if multiple boards are
being used.
JUMP9 5V This jumper selects the voltage of the device under
test supply (V
DUT
= 5 V or 3 V). This jumper is
typically the only jumper that changes for most
applications.
JUMP10 WP ON This write protects the firmware EEPROM.
JUMP11 WP ON This write protects the calibration EEPROM.
JUMP13 REG Uses the regulator output to generate the V
DUT
supply. The USB bus can be used as the V
DUT
supply.
JUMP14 9V Uses the external power (9 V as opposed to the
bus)
JUMP17 BUS While in the BUS position, V
DUT
operation is normal.
While in the V
RAW
position, the V
DUT
supply is
connected to an external source. This configuration
allows for any value of V
DUT
between 3 V and 5 V.
(1)
JUMP18 V
DUT
Connects the pull-up on GPIO to the V
DUT
supply or
the V
CC
supply.
(1)
Adjusting beyond this range damages the EVM.
4 BUF22821EVM-USB Features
This section describes some of the hardware features present on the BUF22821 Test Board.
4.1 JMP1: V
SD
Control Setting
Jumper JMP1 selects where the BUF22821 digital supply pin is connected. If JMP1 is set to the INT
position, the DV
DD
pin is connected to the switchable V
DUT
signal generated from the USB_DIG_Platform.
This voltage can be set to either +3.3 V or +5 V, depending on how JUMP9 on the USB_DIG_Platform is
set. While JMP1 is set to the INT position, the V
SD
Power button on the BUF22821 software is able to
control whether the V
DUT
supply voltage is turned on or off.
When JMP1 is set in the EXT position, an external supply connected to terminal T2 can be used to
provide the digital supply voltage for the BUF22821.
12
BUF22821EVM-USB Evaluation Board and Software Tutorial SBOU117–September 2011
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