Hi Leonid,
Can you use the TPS7A57 in your application? That will deliver up to 5A and will give you 5V output. The TPS7A57 will be a better choice for accuracy, however it will cost a few more dollars to implement.
You can parallel the TPS7A20 using ballast resistors. Please see these app notes and let me know what questions you may have. There is no way to connect the reference pins of each TPS7A20 so the error voltage, Ve, is the total accuracy of the LDO (see the EC table).
Comprehensive Analysis and Universal Equations for Parallel LDO's Using Ballast Resistors
Parallel LDO Architecture Design Using Ballast Resistors
The link below provides a new parallel LDO reference design, which should be released in the next month, using the TPS7A57 and ballast resistor technique in case this can help you in your design.
A Scaleable, High-Current, Low-Noise Parallel LDO Reference Design
Thanks,
Stephen
