14.8 COMMUNICATION INTERFACE CHARACTERISTICS
14.8.1 USB - Universal Bus Interface
USB DC Electrical Characteristics
Parameter
Symbol
Conditions
Min.
Input Levels:
Differential Input Sensitivity
VDI
I(D+, D-)
0.2
Differential Common Mode Range VCM
Includes VDI range
0.8
Single Ended Receiver Threshold
VSE
1.3
Output Levels
Static Output Low
VOL
RL of 1.5K ohms to 3.6v
Static Output High
USBVCC: voltage level
VOH
USBV
RL of 15K ohm to VSS
VDD=5v
2.8
3.00
Note 1: RL is the load connected on the USB drivers.
Note 2: All the voltages are measured from the local ground potential.
Figure 45. USB: Data Signal Rise and Fall Time
ST7SCR
Max.
2.5
2.0
0.3
3.6
3.60
Unit
V
V
V
V
V
V
Differential
Data Lines
VCRS
Crossover
points
VSS
tf
tr
USB: Full speed electrical characteristics
Parameter
Symbol
Conditions
Min
Max
Unit
Driver characteristics:
Rise time
tr
Note 1,CL=50 pF
4
20
ns
Fall Time
tf
Note 1, CL=50 pF
4
20
ns
Rise/ Fall Time matching
trfm
tr/tf
90
110
%
Output signal Crossover
Voltage
VCRS
1.3
2.0
V
Note1: Measured from 10% to 90% of the data signal. For more detailed informations, please refer to
Chapter 7 (Electrical) of the USB specification (version 1.1).
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