The RWD QT ESD is a new, ESD protected option of the RWD-QT-LP module for most demanding electrical noise applications.The module supports HitagS256, HitagS2048, Hitag1, Hitag2 and EM4XXX transponders at 125kHz.Evaluation and development are covered by a baseboard product available on www.eccel.co.uk.
The module simply requires a single power and GND connection from the user PCB, along with two connections to an antenna.
Eccel Technology Ltd (IB Technology) provide a range of suitable antennas designed for use with this module (here).
The RWD QT ESD low-power version is a complete 125kHz reader solution for HITAG® 1, HITAG® S256/S2048 (Plain Memory mode), HITAG® 2 (Password mode), EM400X/4102 and MCRF200I/123 passive RFID transponder types.
The RWD QT ESD module is equipped with additional ESD protection components.The first stage of GPIO pins protection is a serial 100 Ohm resistor limiting current. Along with a 470pF capacitor, this creates a low pass filter with cut-off frequency f3dB= 3.4MHz.The second stage protection is clamping diodes (NXP IP4220CZ6 or similar) with a TVS diode protecting 5V power input. As an option, the module can be sold with an eFuse IC (ST STEF05PUR) which is capable of protecting the module from overcurrent and overvoltage on the 5V power line.The antenna pins can be optionally protected by using TVS diodes –SMAJ36CA of equivalent. In this case, the antenna matching circuit may require additional tuning.
As with other RWD modules, all commands and data response are via a simple TTL level RS232 interface. The module provides internal EEPROM memory for holding lists of authorised identity codes, a manual override switch facility and has LED drives to give visual indication of acceptance.
As with the individual MicroRWD versions, the RWD QT ESD is essentially a proximity system and a Read/Write range of up to 20cm can be achieved with the same level of reliable communication and EMC resilience. The unique AST (Adaptive Sampling) feature allows the RWD to continually adjust and re-tune the sampling to allow for inductive changes in the RF field, an essential feature for real-world reliability and robust operation.The communication protocol with the tags can achieve up to 4k bits/second of data transferand the total time, for example, to read a HITAG® 2 four-byte page, including reading of the serial number, selecting the tag and the read operation itself takes less than 100ms.
The RWD QT ESD is ideally suited to battery powered applications; when power (5 V DC) is first applied to the module the red and green LED outputs “flash” once to indicate successful power-up. The device can also check for broken or shorted antenna and can even detect very badly tuned antennas, these problems are indicated by the red LED output “flashing” continuously until the fault has been rectified.