Which reader chip suits a microcontroller project?
The one whose datasheet lists the protocols your tags speak, a bus your microcontroller has, and a supply your board can give. A multiprotocol transceiver such as the TRF7970A covers ISO 14443 A and B, ISO 15693 and FeliCa over SPI or a parallel bus, and drives an antenna you design yourself.
Protocols come first
A reader chip answers the tags its datasheet lists, and nothing else. TI's TRF7970A datasheet announces complete protocol handling for ISO/IEC 15693, ISO/IEC 18000-3, ISO/IEC 14443 A and B and FeliCa, plus NFCIP-1 and NFCIP-2, with encoders, decoders and framing at 106, 212 and 424 kbps. A chip that lists fewer of them will not read what it does not list, whatever you do to the antenna.
So the choice starts from the tags, not from the chip. List what the project must read, in NFC Forum tag types and in standards, with the tag types page if the supplier answered in chip references, then keep only the chips whose datasheet covers all of them.
The bus and the power
The same datasheet gives the wiring. The TRF7970A offers a parallel or SPI interface with a 127 byte buffer, takes 2.7 V to 5.5 V, and has programmable input and output levels from 1.8 V to 5.5 V, which is what decides whether a level shifter appears on your board. Its regulator can supply 20 mA to the microcontroller and the rest of the circuit, and its power down mode draws under 1 µA.
Those numbers matter more than they look. A battery powered device that wakes on a tap lives on the power down figure, and a board whose microcontroller runs at 1.8 V lives on the programmable levels.
What it does with the field
Output power is a setting rather than a property: the TRF7970A is programmable at +20 dBm or +23 dBm, and a dual receiver with signal strength reporting exists to survive read holes and ambient noise. A field detector with programmable wake up levels lets the chip sit quiet until a field appears, which is how the same chip can act as a target rather than as a reader, the subject of the device as a tag page.
Reading at a distance is not one of these settings. What the field reaches is decided by the antenna and by the tag, as the range page explains, and the regulations cap the rest.
What the chip does not give you
An antenna, first. The chip drives a loop you design and match, and the antenna page covers what that involves; a matching network is a measurement, not a schematic to copy.
And the protocol stack above the radio. Complete protocol handling means framing and timing, not the tag type operations: finding an NDEF message on a Type 2 tag or walking the files of a Type 4 tag remains your code, as the Type 2 page and the Type 4 page set out.
Before any of it, ask whether the reader has to be yours. A phone is a reader, and for a project that reads a few tags a day it is the cheaper one, a comparison the platform page makes for production.
Frequently asked questions
How do I know which protocols I need?
List the tags the project must read, by NFC Forum type and by standard, then keep only the chips whose datasheet lists all of them.
Can one chip read tags and also act as one?
Some do. The TRF7970A datasheet lists card emulation and passive target operation beside reader mode, with a field detector to wake on a reader.
Does the chip come with an antenna?
No. It drives a loop you design and match to it, and the matching is measured on your board rather than copied from a reference.
What decides the read distance?
The antenna and the tag, not the output setting. Regulations cap the field, and the antenna decides how much of it reaches the tag.