Power Supplies; Power-Supply Test Points - Texas Instruments ADS9224REVM-PDK User Manual

Power Supplies

4 Power Supplies
The PHI controller provides multiple power-supply options for the EVM, derived from the USB supply of
the computer.
The EEPROM on the ADS9224REVM use a 3.3-V power supply generated directly by the PHI. The ADC
and analog input drive circuits are powered by the
low-noise linear regulator that uses the 5.5-V supply out of a switching regulator on the PHI to generate a
much cleaner 5.0-V output. The 3.3-V supply to the digital section of the ADC is provided directly by an
LDO regulator on the PHI.
The power supply for each active component on the EVM is bypassed with a ceramic capacitor placed
close to that component. Additionally, the EVM layout uses thick traces or large copper fill areas, where
possible, between bypass capacitors and their loads in order to minimize inductance along the load
current path.
The LM7705 outputs a –230-mV option to drive the negative supply (VS–) of the fully-differential input
amplifiers. This option allows the amplifier outputs to swing all the way to ground and achieve a full-scale
differential signal at the ADC input. Configure JP8 in the [1-2] position to use the –230-mV supply for VS–.
If the entire full-scale range is not required, VS– can be connected to GND by configuring JP8 in the [2-3]
position. U8 can be disabled by uninstalling the jumper on JP7.
test points on the EVM.
Designator
TP17
TP18
TP19
TP20
TP21
8
ADS9224REVM-PDK
Table 4. Power-Supply Test Points
Signal
GND EVM ground
LDO_IN_5V5 5.5-V supply from PHI EVM controller
VA 5-V analog supply
DVDD 3.3-V digital supply
VS– Negative supply for fully-differential input amplifiers
Copyright © 2018–2019, Texas Instruments Incorporated
TPS7A4700 onboard the EVM. The TPS7A4700 is a
Table 4 lists the relevant power supply
Description
SBAU315A – July 2018 – Revised June 2019
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