Data Sheet
Copyright © Parallax Inc.  RFID Read/Write Module, Serial & USB (#28440 / 28540)  v2.0 2/22/2018 Page 8 of 10 
ADDR_Serial
 is a unique, read-only serial number with one of 2
32
, or 4,294,967,296, possible values. It 
cannot be changed by the user.  
ADDR_DeviceID
 is a read-only value used to identify the specific tag family (for example, EM4150). The 
32-bit value contains a family code, version code, reserved/unused bits, and a checksum value. It cannot 
be changed by the user.  
Further details of the EM4x50 tag can be found at: 
 www.emmicroelectronic.com/products/rf-identification-security/lf-animal-access-ics/em4450
Electrical Characteristics 
At V
CC
 = +5.0V and T
A
 = 25ºC unless otherwise noted 
Parameter  Symbol  Test Conditions 
Specification 
Unit 
Min. 
Typ. 
Max. 
Supply Voltage 
V
CC
--- 
4.5 
5.0 
5.5 
V 
Supply Current, Idle (Serial) 
I
IDLE
--- 
--- 
9.4 
--- 
mA 
Supply Current, Idle (USB) 
I
IDLE
--- 
--- 
20 
--- 
mA 
Supply Current, Active (Serial) 
I
CC
--- 
--- 
108 
200 
mA 
Supply Current, Active (USB) 
I
CC
--- 
--- 
91 
--- 
mA 
Input LOW voltage 
V
IL
+4.5V <= V
CC
 +5.5V 
--- 
--- 
0.8 
V 
Input HIGH voltage 
V
IH
+4.5V <= V
CC
 +5.5V 
2.0 
--- 
--- 
V 
Output LOW voltage 
V
OL
V
CC
 = +4.5V 
--- 
--- 
0.6 
V 
Output HIGH voltage 
V
OH
V
CC
 = +4.5V 
V
cc
 - 0.7 
--- 
--- 
V 
Absolute Maximum Ratings 
Condition  Value 
Operating Temperature
-40ºC to +85ºC
Storage Temperature
-55ºC to +125ºC
Supply Voltage (V
CC
)
+4.5V to +5.5V
Ground Voltage (V
SS
)
0V
Voltage on any pin with respect to V
SS
-0.3V to +7.0V
NOTICE: 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. 










