CLRC663 datasheet(123/177 Pages) NXP

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NXP Semiconductors

CLRC663

High performance multi-protocol NFC frontend CLRC663 and CLRC663 plus

14 Application information

A typical application diagram using a complementary antenna connection to the CLRC663 is shown in the

following figure.

The antenna tuning and RF part matching is described in the application note [1] and [2].

001aam269

VDD

PVDD

MICRO-

PROCESSOR

host

interface

TVDD

XTAL1

XTAL2

RXN

VMID

TX1

TVSS

TX2

VSS

28-31

PDOWN

IRQ

DVDD

AVDD

RXP

READER IC

CRXN

CRXP

Cvmid

27.12 MHz

antenna

Lant

Figure 36. Typical application antenna circuit diagram

14.1 Antenna design description

The matching circuit for the antenna consists of an EMC low pass filter (L0 and C0), a matching circuitry (C1

and C2), and a receiving circuits (R1 = R3, R2 = R4, C3 = C5 and C4 = C6;), and the antenna itself. The

receiving circuit component values need to be designed for operation with the CLRC663. A re-use of dedicated

antenna designs done for other products without adaptation of component values will result in degraded

performance.

14.1.1 EMC low pass filter

The MIFARE product-based system operates at a frequency of 13.56 MHz. This frequency is derived from a

quartz oscillator to clock the CLRC663 and is also the basis for driving the antenna with the 13.56 MHz energy

carrier. This will not only cause emitted power at 13.56 MHz but will also emit power at higher harmonics. The

international EMC regulations define the amplitude of the emitted power in a broad frequency range. Thus, an

appropriate filtering of the output signal is necessary to fulfill these regulations.

Remark: The PCB layout has a major influence on the overall performance of the filter.

14.1.2 Antenna matching

Due to the impedance transformation of the given low pass filter, the antenna coil has to be matched to a certain

impedance. The matching elements C1 and C2 can be estimated and have to be fine-tuned depending on the

design of the antenna coil.

CLRC663

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 5.3 — 3 January 2024

123 / 177

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