HTRC11001T/03EE View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

Manufacturer

HTRC11001T/03EE

HITAG reader chip

NXP Semiconductors. 

NXP Semiconductors

HTRC110

HITAG reader chip

9. Functional description

9.1 Power supply

The HTRC110 works with an external 5 V± 10 % power supply at VDD. The maximum

DC-current is 10 mA+Îant*2/ π = 137 mA. For optimum performance, the power supply

connection should be by-passed to ground with a 100 nF capacitor close to the IC.

9.2 Antenna driver, data input

The drivers deliver a square shaped voltage to the series resonant antenna circuit. Due to

the full bridge configuration of the drivers this voltage Udrvpp is approximately 10 V

(peak-peak) corresponding to Ûdrv = 5 V. The current flowing through the antenna is sine

shaped. It´s amplitude is approximately:

9.3 Diagnosis

In order to detect an antenna short or open condition the antenna tap voltage is

monitored. An antenna fail condition is reported in the status bit ANTFAIL (see Table 16),

if the antenna tap voltage does not go more negative than the diagnosis level DLEV (see

Table 18). This condition is checked for every coil driver cycle.

9.4 Oscillator/programmable divider/clock

The crystal oscillator at XTAL1/2 works with either crystal or ceramic resonators. It

delivers the input clock frequency of 4, 8, 12 or 16 MHz. The oscillator frequency is

divided by a programmable divider to obtain the carrier frequency of 125 kHz (see

Table 12). Alternatively, an external clock signal (CMOS compatible) may be fed into the

IC via XTAL1. For example, this signal can be derived from the microcontroller clock.

9.5 Adaptive sampling time demodulator

The demodulator senses the absorption modulation applied by a transponder when

inserted into the field. The signal is picked up at the antenna tap point between La and Ca.

It is divided by Rv and the internal resistor Rdem_in to a level below 8 V (peak) with respect

to QGND at the RX-pin (see Figure 3). Internally the signal is filtered with a second order

low pass filter.

The antenna current and therefore the tap voltage is modulated by the transponder in

amplitude and/or phase. This signal is fed into a synchronous demodulator recovering the

baseband signal. The amplification and the bandpass filter edge frequencies of the

demodulator can be adapted to different transponders via settings in the configuration

pages.

037031

Product data sheet

PUBLIC

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

Rev. 3.1 — 9 February 2010

037031

© NXP B.V. 2010. All rights reserved.

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