Datasheet

2.2.1.1 Power Supply Option 1
2.2.1.2 Power Supply Option 2
2.2.1.3 Power Supply Option 3
Circuit Description www.ti.com
Table 3. EVM Power Supply Options
EVM Option Evaluation Goal Jumper Changes Required Voltage on J7 Comments
1 Evaluate ADC JP13 → 1-2; JP14 → 1-2; JP16 → 1-2; 6 V - 36 V Maximum performance and
performance using JP19 → 2-3; JP17 → 1-2; efficiency.
a cascaded
switching power
supply
(TPS5420D) and
LDO solution
(TPS79501DCQ)
2 Evaluate ADC JP13 → 1-2; JP14 → 1-2; JP16 → 1-2; 5.1 V - 5.5 V Maximum performance.
performance using JP19 → 1-2, JP17 → No shunt;
a LDO-based
solution.
3 Evaluate ADC JP13 → connect 3.3V to pin 2 of Do not apply power Isolated power supply for
performance using Jumper; JP14 → connect 3.3V to pin 2 of on J7. current consumption
an isolated ADC Jumper; JP16 → No shunt ; JP19 → No measurements
AVDD and DVDD shunt ; JP17 → No shunt;
for current
consumption
measurements
Option 1 supplies the power to the ADC using cascaded topology of the TPS5420D switching power
regulator and the TPS79501DCQ Low Dropout (LDO) regulator. The TPS5420 is a step-down converter
which works with the input voltage in the range 6 V to 36 V. The switching supply increases efficiency for
higher input voltages but does create noise on the voltage supplies. To reduce the noise, an
ultralow-noise, high-PSSR LDO TPS79501DCQ is used to clean the power supply. The TPS5420D is
designed for output of 5.3 V, which acts as input for TPS79501. The TPS79501 is designed to output a
5-V output, which is the AVDD for the ADC. This voltage rail is input to the LDO TPS79633, which outputs
3.3 V, used for DVDD for the ADC. A separate TPS79633 is designed to output 3.3 V for the CDCE72010
power supply rail. This solution adds two features to the EVM: one is to increase the range of the power
supply on jumper J7 from 6 V to 36 V, 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, ensuring the better performance of the part even when the power source is
fluctuating.
Option 2 supplies power to the ADC using the LDOs TPS79633DCQ and TPS79601DCQ. The LDOs limit
the power supply on J7 to be in the range 5.1 V to 5.5 V only. When using this option, take care powering
up the EVM as higher voltage or reverse polarity can damage the EVM. This is the default power supply
configuration for the ADS61x9/55xx.
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 as reversing the power supply
or connecting to the wrong connector can result in damage to the EVM. One common usage of this option
is to measure the separate current consumption of the relative supplies under particular operating
conditions. For this option, the shunts on jumpers JP13 and JP14 are removed and the input power is
supplied to the center post of the jumper. For convenience, a ground post is provided next to the center
post for header connections that contain power and ground on 0.1" centers.
ADS61x9/55xxEVM 10 SLWU061A – December 2008 – Revised June 2009
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