28140 Parallax Inc, 28140 Datasheet - Page 5

• Manufacturer Part Number: 28140
• Description: READER MODULE RFID
• Manufacturer: Parallax Inc

Specifications of 28140

• Rf Type: Read Only
• Frequency: 125kHz
• Features: Single 5V Power Supply
• Package / Case: Module
• Product: Microcontroller Accessories
• Data Bus Width: 8 bit
• Clock Speed: 125 KHz
• Interface Type: USB
• Operating Supply Voltage: 5.5 V
• Board Size: 46.99 mm x 69.22 mm x 21.84 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

Interference
The Parallax RFID Card Reader, like many RF devices, may experience RF noise in its frequency range.
This may cause the reader to transmit a spurious tag response when no tag is near the unit. This will not
affect most uses of the RFID Card Reader. To completely prevent spurious responses, it is recommended
to simply read two responses in a row within a given amount of time (e.g. 1 second) to ensure that you
are reading a valid tag and not a “tag” generated by noise.
DC Characteristics
At V
Absolute Maximum Ratings
Stresses above 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 those or any other
conditions above those indicated in the operation listings of this specification is not implied.
Exposure to maximum rating conditions for extended periods may affect device reliability.
RFID Technology Overview
Material in this section is based on information provided by the RFID Journal (www.rfidjournal.com).
Radio Frequency Identification (RFID) is a generic term for non-contacting technologies that use radio
waves to automatically identify people or objects. There are several methods of identification, but the
most common is to store a unique serial number that identifies a person or object on a microchip that is
attached to an antenna. The combined antenna and microchip are called an "RFID transponder" or "RFID
tag" and work in combination with an "RFID reader" (sometimes called an "RFID interrogator").
An RFID system consists of a reader and one or more tags. The reader's antenna is used to transmit
radio frequency (RF) energy. Depending on the tag type, the energy is "harvested" by the tag's antenna
and used to power up the internal circuitry of the tag. The tag will then modulate the electromagnetic
Copyright © Parallax Inc.
CC
Supply Voltage
Supply Current, Idle
Supply Current, Active
Input LOW voltage
Input HIGH voltage
Output LOW voltage
Output HIGH voltage
= +5.0V and T
Parameter
Condition
Operating Temperature
Storage Temperature
Supply Voltage (V
Ground Voltage (V
Voltage on any pin with respect to V
A
= 25ºC unless otherwise noted
RFID Card Reader Serial & USB (#28140 / 28340)
V
I
I
V
V
V
V
IDLE
CC
cc
Symbol
CC
IL
IH
OL
OH
ss
)
)
---
---
---
+4.5V <= V
+4.5V <= V
V
V
CC
CC
= +4.5V
= +4.5V
ss
Conditions
Test
CC
CC
<= +5.5V
<= +5.5V
4.5
---
---
---
2.0
---
V
CC
Min.
- 0.7
Value
-40ºC to +85ºC
-55ºC to +125ºC
+4.5V to +5.5V
0V
-0.3V to +7.0V
Specification
v2.1 8/28/2008 Page 5 of 11
5.0
10
100
---
---
---
---
Typ.
5.5
---
---
0.8
---
0.6
---
Max.
V
mA
mA
V
V
V
V
Unit