Texas Instruments TLV320DAC26EVM, Руководство пользователя

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Switches
3-3 Operation
3.1.5 Power Supply Current Measurement
Four jumpers are on the front of the four power supply pins of the DAC26. The
jumpers can be replaced by current meters that measure and monitor the
currents in the corresponding power supply pins. See the note accompanying
Table 2−1.
3.1.6 IOVDD Voltage Selection
One of the features of the DAC26 is the flexibility of the digital IO power supply
with a range from 1.1 V to 3.6 V. To evaluate this feature, the EVM has the
JMP9 jumper for IOVDD selection. If JMP9 is at 1 to 2 position, IOVDD is 3.3
V; if JMP9 is at 2 to 3, IOVDD is 1.8 V: and without JMP9, an extra power supply
(1.1 V to 3. 6 V) can be connected to IOVDD.
3.2 Switches
The onboard SW1 switch gives users the option to select SPI and I
2
S as well
as MCLK signal resources. Table 3−2 shows the function of the switch.
Table 3−2. Switch Function Reference
Reference
Designator
Setting Function Factory Default Subsection
SW1-1
ON Onboard I
2
S selected
ON 3.2.2 SW1-1
OFF External I
2
S selected
ON 3.2.2
SW1-2
ON Onboard MCLK selected
ON 3.2.3
SW1
SW1-2
OFF External MCLK selected
ON 3.2.3
SW1
SW1-3
ON Onboard SPI selected
ON 3.2.1 SW1-3
OFF External SPI selected
ON 3.2.1
SW1-4
ON USB Reset connected to DAC26
ON 3.2.4 SW1-4
OFF USB Reset not connected to DAC26
ON 3.2.4
3.2.1 SPI Selection
The SPI bus on the DAC26 provides the main interface between a
host-processor and the DAC26 device. The onboard TAS1020B plays the role
of the host processor, if SW1-3 is set to the ON position. If an external
processor or SPI device is used, set the SW1-3 to the OFF position so as to
disable the onboard SPI interface to the TAS1020B and open the DAC26 SPI
port to the external SPI bus.
3.2.2 I
2
S Selection
The I
2
S bus on the DAC26 can interface with the onboard host processor, the
TAS1020B USB controller, or with other offboard external I
2
S processor or
devices. When SW1-1 is set to ON, the manufacturer default, the DAC26 I
2
S
is connected to the TAS1020B’s I
2
S. Otherwise, if SW1-1 is shifted to OFF, the
buffer between the onboard I
2
S port is disabled so that an external I
2
S can
communicate with the DAC26 I
2
S port.