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Circuit Description
Table 2. EVM Power Supply Jumper Description
EVM Jumper
Description
Jumper
Default 5V Supply Input
J10
Power Supply Input
6V to 36V Supply Input for Power Supply Option 2
J17 (same node as
Default 5V Supply Input
Power Supply Jack
J10)
6V to 36V Supply Input for Power Supply Option 2
1-2
→
Connects U11 Output to Input of U14
JP16
U14 Input Select
2-3
→
Connects Supply Voltage at J10 or J17 to Input of U14
1-2
→
Connects Supply Voltage at J10 or J17 to 5V_AUX
JP19
5V_AUX
2-3
→
Connects TPS7A4501 Output to 5V_AUX
JP17
U11 Enable
Shunt
→
J10 or J17 connected to U11
Table 3. EVM Power Supply Options
EVM
Evaluation Goal
Jumper Changes Required
Voltage on J10
Comments
Option
JP17
→
No Shunt
JP16
→
1-2
Evaluate ADC performance using
Maximum ADC
1
JP19
→
1-2
5.0V to 5.5V
a LDO based solution
performance
JP15
→
1-2
JP18
→
1-2
JP17
→
1-2
Evaluate ADC performance using
Maximum ADC
JP16
→
1-2
a cascaded switching power
performance and
2
JP19
→
2-3
6V to 36V
supply (U11) and LDO (U14)
power supply
JP15
→
1-2
solution
efficiency
JP18
→
1-2
JP17
→
No Shunt
Evaluate ADC performance using
Isolated power supply
JP16
→
No Shunt
an isolated ADC AVDD and
for current
3
JP19
→
No Shunt
Do not apply power
DVDD for current consumption
consumption
JP15
→
AVDD to pin 2
measurements
measurements
JP18
→
DVDD to pin 2
2.2.2.1
Power Supply Option 1
Option 1 supplies power to the ADC using the LDOs TPS79633DCQ and TPS79601DCQ. The LDOs take
a maximum input of 5.5V. When using this option, take care powering up the EVM, because higher
voltage or reverse polarity can damage it. This is the default power-supply configuration for the
ADS62PXXEVM.
2.2.2.2
Power Supply Option 2
Option 2 supplies the power to the ADC using cascaded topology of the TPS5420D switching power
regulator and the TPS7A4501 Low Drop-Out regulator. The TPS5420 is a step-down converter which
works with the input voltage in the range 6V to 36V. The switching supply increases efficiency for higher
input voltages but does create noise on the voltage supplies. To reduce the noise, an low-noise,
high-PSSR LDO TPS7A4501 is used to clean the power supply. The TPS5420D is designed for 5.3V
output, which acts as a supply for the TPS7A4501. The TPS7A4501 is designed to output 5V. This voltage
rail is input to the LDO TPS79633, which outputs 3.3V, used for the ADC. A separate TPS79633 is
designed to output 3.3V for the CDCE72010 supply rail. This solution adds two features to the EVM: one
is to increase the range of the power supply on jumper J10 from 6V to 36V, allowing the user to choose
any power supply source in the specified range without causing significant power dissipation. The other
feature is that the output-voltage rail has a much lower ripple, allowing better performance of the part even
when the power source is fluctuating.
2.2.2.3
Power Supply Option 3
Option 3 is used to evaluate ADC performance using an isolated AVDD and DVDD power supply for
current-consumption measurements. This option must be used with caution, because reversing the power
9
SLAU237B – May 2008 – Revised July 2010
ADS62PXXEVM
Copyright © 2008–2010, Texas Instruments Incorporated
