SLAU443 Datasheet, PDF (15/68 Pages) Texas Instruments – EEG Front-End Performance Demonstration Kit

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ADS1299EEG-FE Daughter Card Hardware Introduction
Table 2. Power Supply Test Points
Test Point
TP7
TP9
TP10
TP5
TP13
TP6
TP8
Voltage
+5.0V
+1.8V
+3.3V
+5.0V
+2.5V
–2.5V
GND
The front-end board must be properly configured in order to achieve the various power-supply schemes.
The default power-supply setting for the ADS1299EEG-FE is a unipolar analog supply of 5V and DVDD of
either +3V or +1.8V. Table 3 shows the board and component configurations for each analog power-
supply scheme; Table 4 shows the board configurations for the digital supply.
Table 3. Analog Supply Configurations
Power Supplies
JP2 (AVDD)
JP20 (AVSS)
U8
U9
Unipolar Analog Supply
5V
2-3 (default)
1-2 (default)
Don’t Care
Don’t Care
Bipolar Analog Supply
±2.5V
1-2
2-3
TPS72325
TPS73225
DVDD
JP24
Table 4. Digital Supply Configurations
+3.0V
2-3 (default)
+1.8V
1-2
4.2 Clock
The ADS1299 has an on-chip oscillator circuit that generates a 2.048MHz clock (nominal). This clock can
vary by ±5% over temperature. For applications that require higher accuracy, the ADS1299 can also
accept an external clock signal. The ADS1299EEG-FE provides an option to test both internal and
external clock configurations. It also provides an option to generate the external clock from either the
onboard oscillator or from an external clock source.
The onboard oscillator is powered by the DVDD supply of the ADS1299. Care must be taken to ensure
that the external oscillator can operate either with +1.8V or +3.0V, depending on the DVDD supply
configuration. Table 5 shows the jumper settings for the three options for the ADS1299 clocks.
ADS1299 Clock
JP18
JP19
J3– pin 17
Table 5. Clock Jumper Options
Internal Clock from the ADS1299
Not Installed
Don’t Care
Don’t Care
Clock from Oscillator on the EVM
2-3 (default)
1-2
Don’t Care
External Clock Source
1-2
Don’t Care
External Clock Source
SLAU443 – May 2012
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