EVB90109_12 Datasheet, PDF (3/10 Pages) Melexis Microelectronic Systems – MLX90109 Evaluation Board

EVB90109
MLX90109 Evaluation Board
1 EVB90109 Electrical Specifications
Parameter
Supply Voltage
Resonance frequency
Condition
Vdd = 5Volts
Symbol Min Typ Max Units
Vdd
4.5
5
5.5
Volts
Fres
120
125
130
kHz
Table 1: Electrical specifications
2 Description
2.1 General explanation
The EVB90109 consists of a single chip inductive RFID reader for the 125 kHz frequency range with an
external inductance (L) and capacitance (C) connected as a parallel resonant circuit. The antenna voltage
amplitude can be set On/Off externally with the digital line MODUR2, which controls a resistive and capacitive
network called “Modulation network” connected to the MODU pin of the chip. This allows maximum reading
distance and reliability, can be used to preserve energy by easily setting the evaluation board in power down
mode and finally allows 100% modulation for reader talk first applications. The EVB90109 also includes a
“fast decay” circuit composed of an external transistor and diode in parallel to the resonant antenna, used to
short the antenna for negative swings to dissipate the remaining energy into the transistor and then, to
reduce the fall time of the antenna. For more information, please refer to the application note “100%
Modulation (On/Off keying)”. An additional footprint of “Modulation network” is available on the board and is
accessible through the MODUR3 digital connection. All others digital connections as SPEED, MODE, MODU,
CLOCK and DATA, are available on the DIL-10 connector.
Parallel resonant antenna (L, C4, C5)
Connector DIL-10
MLX90109
Modulation Network (R1, R2)
Fast decay circuit (Q1,
Figure 1: EVB90109
Note: The EVB90109 does not include any pull-up resistors on the digital connections DATA and CLOCK.
This must be done externally, by configuring the IO ports of a microcontroller in pull-up mode, or by adding
two external resistors connected between the digital pins and Vdd.
390129010901
Rev 006
Page 3 of 10
Evaluation Board
Aug-2012