sip5628 Vishay, sip5628 Datasheet - Page 10

• Manufacturer Part Number: sip5628
• Description: 14-line Scsi Bus Terminators
• Manufacturer: Vishay

SiP5628
Vishay Siliconix
DETAILED OPERATION
The SiP5628 is a multimode active terminator IC, which
detects the operating mode of the SCSI bus, and switches to
the appropriate termination configuration accordingly.
Two SiP5628 terminators are required at each end of a wide
SCSI bus to terminate 27 lines (18 data, 9 control). In LVD
mode the SiP5628 provides 105-Ω differential impedance and
112-mV differential bias between each TN/TP pair of
terminator lines. In S/E mode the SiP5628 provides 108-Ω
impedance and 2.7-V pull-up on each TxN pin, and low
impedance to ground on each TxP pin. In HPD mode the
SiP5628 disconnects from the bus and presents high
impedance to all TN/TP lines.
Each SiP5628 IC has a 1.3-V DIFFSENS regulator output that
can be used to drive the DIFFSENS line of a SCSI bus. The
DIFFSENS regulator attempts to drive the DIFFSENS control
signal to 1.3 V, but is current limited so that S/E or HPD devices
on the SCSI bus can override the DIFFSENS regulator and put
the bus into S/E or HPD mode of operation.
The MODE pin senses the operational state of the SCSI bus
by detecting the voltage on the DIFFSENS control line through
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Package Reliability represent a composite of all qualified locations.
http://www.vishay.com/ppg?73097.
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an external R/C lowpass filter. 50 kΩ/4.7mF are recommended
component values for the filter to meet SPI-3 mode change
requirements.
Two status lines (S/E and LVD) are provided by the SiP5628.
One and only one status line is asserted HIGH when its
corresponding mode has been detected; the other status line
is driven low. Both status lines are driven low when HPD mode
is detected.
The DISABLE pin is used to connect/disconnect the SiP5628.
If it is pulled to GROUND the SiP5628 is in connect mode, and
operates as a terminator. If it is pulled to TRMPWR or left open
the device is in disconnect mode and presents high
impedance to the SCSI bus.
DIFFSENS Regulator is disabled but the mode detection
circuitry continues to function and the status lines continue to
indicate which mode is detected.
The SiP5628 operates within SCSI specifications with the
TERMPWR voltage between 2.7 V and 5.25 V, which enables
it to operate in both 5-V and 3.3-V systems. The 2.7-V lower
limit guarantees correct performance in a 3.3-V system.
In disconnect mode the
S-41843—Rev. A, 11-Oct-04
Document Number: 73097