ss8219g Silicon Standard Corporation, ss8219g Datasheet - Page 2

• Manufacturer Part Number: ss8219g
• Description: Ultra320 Multi-mode Lvd/se Scsi Terminator
• Manufacturer: Silicon Standard Corporation

12/06/2005 Rev.3.01
ORDERING INFORMATION
APPLICATION INFORMATION
To ensure proper operation, the TPWR pin should be
connected to the SCSI bus TERMPWR line. As with all
trace length, thereby reducing the input capacitance
The SS8219G is used in multi-mode active-termination
applications where single ended (SE) and low voltage
differential (LVD) devices might coexist. The LVD termin-
ation section consists of 18 source/sink amplifiers (VTOP,
VBOT), biasing circuitry and nine precision resistor
strings (RTOP, RMID, RBOT). The SE termination
section consists of a 2.85V source/sink regulator with
nine precision 110Ω resistors. The DIFFSENSE section
consists of a 1.3V, 5mA driver and a sensing circuit (Fig.1).
DIFFSENS is used to identify which types of SCSI
devices are present on the bus. If the voltage on
DIFFSENS is between 0V and 0.5V the bus is single-
ended; if it is between 0.7V and 1.9V, the bus is LVD;
and if it is greater than 2.4V, the bus is HVD.
The SS8219G DIFFB pin monitors the DIFFSENS line
to determine the proper operating mode of the device.
HVD Isolation Mode:
is an HVD (high voltage differential) device on the SCSI
bus and isolates the termination pins from the bus.
When DISCNCT is pulled high, or during thermal
shutdown, the termination pins are isolated from the
SCSI bus and VREF is grounded. The DIFFSENSE
driver is shut down during either of these two events.
analog circuitry, the TERMPWR lines should be by-
passed locally. A 2.2µF capacitor and a 0.01µF high
frequency capacitor are recommended between TPWR
and ground and placed as close as possible to the
SS8219G. The IC should be placed as close as possible
to the SCSI connector to minimize both signal and power
Please note for the following sections :
SS8219GX XX
DIFFSENS - refers to the SCSI bus signal.
DIFFSENSE - refers to the SS8219G pin name and internal circuitry related to differential sensing.
DIFFB - refers to the SS8219G pin name and internal circuitry related to monitoring the DIFFSENS line.
The SS8219G identifies that there
GD = RoHS-compliant TSSOP-28
GS = RoHS-compliant SSOP-36
TR = tape and reel; TB = tubes
www.SiliconStandard.com
LVD termination is provided by a precision resistor
is required between the VREF pin and ground of each
SS8219G. A high frequency capacitor (0.1µF ceramic
this internal digital filter.
and reflections which can degrade the bus signals.
The DIFFSENSE pin can drive the SCSI DIFFSENS
line (when M/S is pulled high) to determine the SCSI
bus operating mode. The SS8219G switches to the
appropriate termination mode for the bus based on
the value of the DIFFSENS voltage. These modes are:
LVD mode:
string with two amplifiers. This configuration yields a
105Ω differential and 150Ω common mode impedance.
A fail safe bias of 112mV is maintained when no drivers
are connected to the SCSI bus.
SE mode:
When the external driver for a given signal line turns
off, the active terminator will pull that signal line
to 2.85 volts (quiescent state). When used with an
active-negation driver, the power amp can sink 22mA
per line while keeping the voltage reference in regulation.
The terminating resistors maintain their 110 Ω value.
To maintain the specified regulation, a 4.7µF capacitor
recommended) can also be placed on the VREF pin
in applications that use fast rise/fall time drivers. A
typical SCSI bus configuration is shown in Figure 2.
An internal pull-down resistor assures that the SS8219G
will still terminate the bus if the DISCNCT pin is left floating.
DIFFSENS noise filtering
The SS8219G incorporates an internal digital filter to
remove the noise signal on the DIFFSENS control line,
thereby eliminating erroneous switching between
modes. An external filter may also be used in addition to
For example: SS8219GD TR
=> SS8219 in RoHS-compliant TSSOP-28
supplied on tape and reel
SS8219G
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