February 1997
ML6599*
Hot-Insertable Active SCSI Terminator
GENERAL DESCRIPTION
The ML6599 BiCMOS 9 line SCSI terminator provides
active termination in SCSI systems using single ended
drivers and receivers. Active SCSI termination helps to
effectively control analog transmission line effects such as
ringing, noise, crosstalk, and ground bounce. In addition,
the ML6599 provides support for hot-insertability on the
SCSI bus.
The ML6599 provides a V-I characteristic optimized to
minimize transmission line effects during both signal
negation and assertion using a MOSFET-based
architecture. The desired V-I characteristic is achieved by
trimming one resistor in the control block. Internal
clamping controls signal assertion transients and provides
current sink capability to handle active negation driver
overshoots above 2.85V. It provides a 2.85V reference
through an internal low dropout (1V) linear regulator.
The ML6599 also provides a disconnect function which
effectively removes the terminator from the SCSI bus. The
disconnect mode capacitance is typically less than 5pF
per line. Current limiting and thermal shutdown
protection are also included.
FEATURES
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Fully monolithic IC solution providing active
termination for 9 lines of the SCSI bus
Provides on board support for hot-insertability on the
SCSI bus
Low dropout voltage (1V) linear regulator, trimmed for
accurate termination current
Output capacitance typically < 5pF
Disconnect mode — logic pin to disconnect terminator
from the SCSI bus, <100µA
Current sinking — can sink current in excess of 10mA
per line to handle active negation driver overshoots
above 2.85V
Negative clamping on all lines to handle signal
assertion transients
Regulator can source 200mA and sink 100mA while
maintaining regulation
Current limit & thermal shutdown protection
*Some Packages Are Obsolete
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BLOCK DIAGRAM
TERMPWR
V
REF
DISCNKT
2.85V
LINEAR
REGULATOR
1V DROPOUT
2.85V
GND
R
TRIM
V
REF
CONTROL
BLOCK
MOSFETs WITH I
MAX
= 24mA
...
NCLAMP
...
...
...
NCLAMP
NCLAMP
L1
NCLAMP = Negative Clamp
L2
...
L9
9 TERMINATION LINES
1
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
