Datasheet

Circuit Description
3-9
Operation
When the firmware is loaded and active, D2 (a yellow LED) is lit. If no firmware
is loaded, the U10 output should be in 3-state. In order to ensure that the
onboard host processor does NOT effect the interface between the external
SPI bus to drive the TSC2101, turn OFF the SW2−3.
When the SW2−3 is ON and the firmware is loaded, the PC software enables
the onboard microprocessor to control the SPI bus.
Caution
Do not drive the external SPI bus when the firmware is loaded and
the onboard microprocessor is active. If you want to use the
external SPI bus, disable the microprocessor by removing JMP5,
turning OFF the SW2−3 to isolate the microprocessor SPI bus, and
cycling power to the TSC2101EVM.
Likewise, the I
2
S signals for the digital audio can be driven either externally by
J13 or by the USB audio controller.
Caution
Do not drive the external I
2
S bus when the firmware is loaded and
the onboard microprocessor is active. If you want to use the
external I
2
S bus, disable the microprocessor by removing JMP5,
turning OFF the SW2−1 to isolate the microprocessor I
2
S bus, and
cycling power to the TSC2101EVM.
3.4.2 Power Supply
Power to the TSC2101EVM can be derived directly from the USB interface or
externally supplied through the J11 terminal block or the J12 barrel jack
connector. Supply voltages of 6 Vdc to 10 Vdc must be supplied from an
external supply. Because it is regulated on the TSC2101EVM, this input
voltage does not need to be regulated as long as it falls within this range. D1
prevents damage to the board in the event a power supply is connected in
reverse polarity.
Two linear regulators are on the board. U3 regulates the digital power-supply
voltage to provide 1.8 V for the TSC2101 digital core, or the digital IO power
supply if the IOVDD is selected as 1.8 V by JMP7. Also, U3 provides the 3.3-V
digital power for all of other digital circuits. U4 regulates the analog power
supplies. Its 3.9-V power supply is used for the TSC2101 analog driver power
DRVDD2; its 3.3 VA powers the rest of the analog circuits on the board.
The regulated supply voltages have LEDs attached that alert the user that the
supply is working. D2 (red) is the indicator for the 1.8-V power supply; D4
(green) is the indicator for the 3.3-V power supply; D5 (green) is the indicator
for the 3.9-V driver power; and D6 (green) is the indicator for the 3.3-VA analog
power supply.