uss820d-db ETC-unknow, uss820d-db Datasheet - Page 49

• Manufacturer Part Number: uss820d-db
• Description: Uss-820d Device Controller
• Manufacturer: ETC-unknow

June 2001
Agere Systems Inc.
Electrical Characteristics
Power Considerations
The USB specification places current limits on bus-powered devices. The limit is tighter for a device that has not
yet been configured. The tightest limit is for a suspended device.
The current values listed in Table 44 for a preconfigured device assume fairly low activity (about 5%) on USB. The
maximum value for a configured device assumes the device is transmitting 80% of the time on USB. All current
values assume a 35 pF load on the package pins.
The limit for suspended devices can only be met if careful measures are taken to control the interface to the USS-
820D, as documented in the Suspend and Resume Behavior section.
USB Transceiver Driver Characteristics
Table 45. USB Transceiver Driver Characteristics
* At steady-state drive, when used with an external series resistor of 24 Ω.
Rise and Fall Times:
Rise/Fall Time Matching
Crossover Point
Output Impedance*
(10%—90%)
(90%—10%)
Parameter
(continued)
Symbol
V
Z
t
RFM
CRS
DRV
t
t
R
F
OEN = 0, C
OEN = 0, C
OEN = 0, C
OEN = 0, C
Test Conditions
OEN = 0
L
L
L
L
= 50 pF
= 50 pF
= 50 pF
= 50 pF
USB Device Controller
Min
1.3
90
28
4
4
Max
110
2.0
20
20
43
Unit
ns
ns
%
Ω
V
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