Texas Instruments ADS4449 EVM, Руководство пользователя

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GND
6 V
J2
J3
TPS62420
JP2
1
TPS7A8001
LDO 3.3 V
To ADC
To ADC
PWR IN
J1
TPS2400
JP3
1
JP6
1
TPS7A8001
LDO 1.9 V
JP5
1
Overvoltage
Protection Circuit
Dual Output
DC/DC Converter
Low Noise LDO
Low Noise LDO
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Introduction
3 SLAU485A – January 2013 – Revised April 2016
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ADS4449 EVM User Guide
1.2 EVM Power Supply
Figure 2 illustrates the power supply options available on the EVM. Jumpers are used to choose the
power supply options, with the default jumper positions indicated by the darker portion of the jumper that
represents the presence of the jumper. For jumper and feedback resistor configuration, see
Table 1 .
Figure 2. Simplified ADS4449 EVM Power Supply
Table 1. Power Supply Options
Power Supply
Options
JP2 JP3 JP4 JP5 R3 R7 Comment
Option #1
(Default)
1-2 1-2 1-2 1-2
649
k
Ω
536
k
Ω
Dual outputs DC/DC converter supplies 3.85 V and 2.4 V to two
low-noise LDOs. The low-noise LDOs output 3.3 V and 1.9 V,
respectively.
Option #2 2-3 2-3 2-3 2-3
536
k Ω
390
k Ω
Low-noise LDOs are bypassed. DC/DC converter powers the
ADC directly.
The default power path has an efficient dual output DC-DC switching power supply to first step down the
input supplies for the low-noise LDOs. The low-noise LDOs generate the 3.3 V and 1.9 V for the ADC
power.
The low-noise LDOs can be bypassed, allowing the DC/DC power supply to directly power the ADC. In
this implementation, adjust the feedback resistors of the DC/DC converter accordingly.