Ldo Configurations - Analog Devices ADRV9001 User Manual

Reference Manual

LDO CONFIGURATIONS

Note: Consider this section carefully. Failure to implement the LDO modes correctly can result in an incorrect voltage being applied and
potentially damage the RF circuits.
The VDDA_1P0 is a power domain that powers all the transmitter and receiver LO circuits. Power this domain using internal LDOs that
generate the 1 V needed from the 1.3 V supply. Alternatively, power it externally by bypassing some of the internal LDOs. Use this in cases
requiring power savings or with an already available 1 V supply in the system. Save some power by turning off the LDOs and applying a higher
efficiency external power source to the 1 V rails. The new 1 V external power domain is a low-noise supply with a tolerance of ±2.5%.
The LDO configurations on the ADRV9001 can affect the overall power consumption. On the ADRV9001 evaluation board, all the internal LDOs
are used and they generate the 1 V needed for all the rails. This allows for different RF channels while evaluating. In an end system, the user
knows what RF channels they are using and can tailor the RF channels to the system.
To implement an ideal LDO configuration for the end use case:
Use the application to determine how many transmitter, receiver, and LO channels are needed.
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Design a power supply to implement the determined use case.
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Choose what LDO configuration is needed and set the LDO modes appropriately.
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APPLICATION POWER NEEDS
Deciding what LDOs to use/bypass depends on the transmitter, receiver, and LO combinations going to be used. For example, in the 1T/2R
FDD use case, do not use one of the transmit channels and then power down the internal LDOs for this channel. The
Configurations section provides details on how to wire the power domains.
The following board power supply configurations are supported.
CHOOSING THE LDO CONFIGURATION
Before choosing the proper LDO configurations, it is important to understand the power domains used in the system. The LDO configurations
vary depending on the use of RF channels, internal/external LO, or if an external VDDA_1P0 is supplied. Take care when setting the LDO
modes to avoid any potential incorrect voltages getting supplied to the internal blocks.
Table 122 shows the LDO operating modes. Use the enumerators for each mode when setting up the adi_adrv9001_powermanagement_Con-
figure function.
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Figure 279. Power-Saving LDO Configurations
Figure 279 shows three examples.
ADRV9001
Power-Supply
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