VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
3.2Gb/s
36x37 Crosspoint Switch
VSC838
Output Termination
The high-speed outputs of the VSC838 are internally back terminated by 50Ω to V
when the
CC
TERM_CTRL pin is HIGH. When this pin is LOW, the output driver functions as an open-drain CML driver.
Setting DRIVE_CTRL LOW (GND) saves 1W under maximum power dissipation conditions. See Table 9 for
allowable types of terminations and modes of operation.
Table 9: Allowed High-Speed Output Terminations and Modes of Operation
(1)
(1)
VOD
VOCM
(V)
DRIVE_
CTRL
TERM_
CTRL
Type
Description
(mV)
typ
typ
1
2
3
4
5
6
7
8
AC-coupled to 50Ω termination to any voltage
AC-coupled to 100Ω differential termination
VCC (HIGH)
VCC (HIGH)
GND (LOW)
VCC (HIGH)
GND (LOW)
VCC (HIGH)
GND (LOW)
VCC (HIGH)
VCC (ON)
VCC (ON)
GND (OFF)
GND (OFF)
VCC (ON)
VCC (ON)
500
500
500
1000
250
500
250
500
2.0
2.0
DC-coupled, terminated in 50Ω to VCC at far-end only
DC-coupled, terminated in 50Ω to VCC at far-end only
DC-coupled, source and far-end terminated in 50Ω to VCC
DC-coupled, source and far-end terminated in 50Ω to VCC
DC-coupled, 100Ω differential termination
2.25
2.0
2.375
2.25
2.25
2.0
VCC (ON)
DC-coupled, 100Ω differential termination
VCC (ON)
NOTE: (1) Measured at output of VSC838, with V = 2.5V.
CC
(1)
Absolute Maximum Ratings
Power Supply Voltage (VCC) Potential to GND ..............................................................................-0.5V to +4.0V
LVTTL Input Voltage Applied ................................................................................................-0.5V to V +1.0V
CC
ECL Input Voltage Applied ....................................................................................................-0.5V to V +0.5V
CC
Output Current (IOUT) .................................................................................................................................... 50mA
o
o
Case Temperature Under Bias (TC)............................................................................................. -55 C to + 125 C
o
o
Storage Temperature (TSTG) ........................................................................................................-65 C to + 150 C
NOTE: (1) Caution: Stresses listed under “Absolute Maximum Ratings” may be applied to devices one at a time without causing perma-
nent damage. Functionality at or exceeding the values listed is not implied. Exposure to these values for extended periods may
affect device reliability.
Operating Conditions
Supply Voltage (VEE).......................................................................................................................................... 0V
Supply Voltage (VCC) ............................................................................................................................+2.5V ±5%
Supply Voltage (VCCP)...........................................................................................................................+2.5V ±5%
o
o
Case Temperature Operating Range (T)..................................................... 0 C to 85 CPackage Pin Descriptions
Page 10
G52351-0, Rev 3.0
02/12/01
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Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
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