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| U3280M Datasheet, PDF (11/18 Pages) ATMEL Corporation – TRANSPONDER INTERFACE FOR MICROCONTROLLER | |||
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U3280M
The antenna coil must be connected with a capacitor as a parallel LC resonant circuit to
the Coil 1 and Coil 2 pins of the IC. The resonance frequency f0 of the antenna circuit
should be in the range of 100 kHz to 150 kHz.
The correct LC combination can be calculated with the following formula:
LA
=
-----------------------1------------------------
CA Ã (2 Ã Ï Ã f0)2
Figure 7. Antenna Circuit Connection
Coil 1
LA
CA
Coil 2
Example: Antenna frequency: f0 = 125 kHz, capacitor: CA = 2.2 nF
LA
=
------------------------------------1--------------------------------------
2.2 nF Ã (2 Ã Ï Ã 125 kHz)2
=
737 µH
Absolute Maximum Ratings
Voltages are given relative to VSS
Parameter
Symbol
Value
Unit
Supply voltage
VDD, VBatt
0 V to +7.0 V with reverse protection
V
Maximum current out of VSS pin
ISS
15
mA
Maximum current into VBatt pin
IBatt
15
mA
Input voltage (on any pin)
VIN
VSS -0.6 â¤VIN â¤VDD +0.6
V
Input/output clamp current (VSS > Vi/Vo > VDD)
IIK/IOK
±15
mA
Min. ESD protection (100 pF through 1.5 kâ¦)
±2
kV
Operating temperature range
Tamb
-40 to +85
°C
Storage temperature range
TSTG
-40 to +125
°C
Soldering temperature (t â¤10 s)
TSD
260
°C
Note: Stresses greater than those listed under absolute maximum ratings may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at any condition beyond those indicated in the operational section of
these specification is not implied. Exposure to absolute maximum rating conditions for an extended period may affect device
reliability. All inputs and outputs are protected against high electrostatic voltages or electric fields. However, precautions to min-
imize build-up of electrostatic charges during handling are recommended. Reliability of operation is enhanced if unused inputs
are connected to an appropriate logic voltage level (for example, VDD).
Thermal Resistance
Parameter
Junction ambient
Symbol
RthJA
Value
180
Unit
K/W
11
4688BâRFIDâ12/04
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