HP7501
Ultra320 LVD/SE SCSI Terminator
FEATURES
Fully compliant with Ultra320 (SPI-4),
Ultra3/Ultra160 (SPI-3), Ultra2/Fast-40 (SPI-2)
and Ultra/Fast-20 Standards.
Auto Selection Multi-Mode SE or LVD
Termination for 9 signal line pairs.
Built-in SPI-4 Mode Change Filter
2.7V to 5.25V Operation
Built in Current Limit and Thermal shutdown
Protection Circuitry.
Support Master/Slave input.
SCSI bus hot plug compatible.
Support active negation drive.
28 and 36 pin package.
DESCRIPTION
The HP7501 is a multi-mode SCSI terminator that
conforms to the SCSI (SPI-4) specification which is
designed for the low voltage differential (LVD)
termination. The HP7501 provides backward
c o m pa t i b i l i t y t o t h e S CS I -2 , S CS I - 1 a n d a
Single-Ended specifications.
Multi-mode function set up the use of legacy devices
on the bus without changing any hardware setting.
Automatic selection is made by voltage detection on
the DIFFSEN line. If the device is connected in an
LVD only bus, the HP7501 will use LVD termination. If
the device is connected in a Single Ended mode, the
H P 7 5 0 1 wi l l c o n n e c t i n a S E t e rm i n a t i o n .
HiMARK’s SCSI termination architecture uses high
speed elements for the design, therefore providing the
fast response time.
PACKAGE PINOUT
VREF
NC
NC
R1P
R1N
R2P
R2N
HGND
HGND
HGND
R3P
R3N
R4P
R4N
R5P
R5N
ISO
GND
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
TPWR
HVD
LVD
SE
R9N
R9P
R8N
R8P
HGND
HGND
HGND
R7N
R7P
R6N
R6P
DIF_CAP
DIFFSENSE
MST/SLV
VREF
R1P
R1N
R2P
R2N
HGND
R3P
R3N
R4P
R4N
R5P
R5N
ISO
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
TPWR
TPWR
R9N
R9P
R8N
R8P
HGND
R7N
R7P
R6N
R6P
DIF_CAP
DIFFSENSE
MST/SLV
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
HP7501-A36
HP7501-T28
2003/05/12
Ver. 0.0
1
HIMARK TECHNOLOGY INC.
HP7501
Ultra320 LVD/SE SCSI Terminator
ORDERING INFOMATION
PART NUMBER
HP7501-A36
HP7501-T28
PIN - PACKAGE
SSOP-36 pin
TSSOP-28 pin
FUNCTIONAL DESCRIPTION
HP 7501 is a multi-mode active terminator with
automatically switching on LVD/SE/HVD mode. The
DIFFSENS* is on one of three voltage levels to indicate
LVD/SE/HVD mode. If the voltage on DIFFSESE** is
above 2.16V, below 0.6V or between, that indicates the
bus mode to be HVD, SE, or LVD.
In Figure 1, a bandgap reference is fed into an buffer
to generate reference voltages. A voltage selected by the
control logic through a MUX is used to generate 2.85V or
1.25V reference voltages. A voltage 2.85V and 1.25V is
used in SE mode and LVD mode respectively. The
voltage for a specific mode is sent out through an op
buffer. In SE mode, the RxP pin is switched to ground.
DIFF_CAP with a RC low pass filter monitors the
voltage on DIFFSENS to determine the termination mode
used on bus. The DIFFERENSE CIRCUITRY decodes
the trinary voltage on DIFF_CAP and generates three
control logic signals internally. The control logic will
change the total termination resistance and switch to one
of three termination modes based on the voltage on
DIFFSENS.
SE Mode
: The voltage on DIFFSENSE is between
0V - 0.5V. RxP pin is grounded. When the external driver
for a given line turns off, the active terminator will pull
that signal line to 2.85V (quiescent state). When
operated in an active negation driver, the power amp can
sink 22mA per line and the reference voltage won’t
change over 100mV. The termination resistors maintain
110ohm.
HVD Mode
: The voltage on DIFFSENSE is above
2.4V. HP7501 will identify that there is an HVD (high
voltage differential) device on the SCSI bus and isolate
the termination pins from the bus.
LVD Mode
: The voltage on DIFFSENSE is between
0.7–1.9V. A precious resistor string between two current
sources provides LVD termination. It offers a 105 ohm
differential mode impedance and a 125 ohm common
mode impedance. A fail-safe bias of 112mV is maintained
when no driver is connected to the SCSI bus.
During high temperature (>150
℃
), HP7501 would
thermal shutdown. The termination pins are isolated from
SCSI bus and Vref becomes high impedance. When
ISO=1, the termination pins are isolated from the SCSI
bus, but the bus mode indicators (SE/LVD/HVD) and Vref
remain active. In the above two cases, the DIFFSENSE
driver is shut down and in high impedance.
The TPWR pin is connected to the SCSI bus
TERMPWR line to power up the HP7501. The TERMPWR
line should be bypassed locally. A 2.2uF capacitor and a
0.01uF high frequency capacitor between TPWR and
ground are suggested for different frequency noise.
Capacitors should be placed as close as possible to the
HP7501. The HP7501 should be placed as close as
possible to the SCSI connector to minimize input signal
trace length and result in less reflections and better
performance.
To maintain the specified voltage, a 4.7uF capacitor is
recommended between the Vref (pin36) and ground. A
high frequency capacitor (0.1uF ceramic recommended)
can also be placed on the Vref pin in applications the use
fast rise/fall time drivers. It is also recommended to place
a RC low pass filter between DIFFSENSE and DIF_CAP
to lower noise from the SCSI bus.
DIFFSENS
Noise
Filtering
:
The
HP7501
incorporates a digital filter to remove high frequency
transients on the DIFFSENS control line. The external
filter may be used as well in addition to the internal digital
filter.
A typical SCSI bus configuration is shown in Figure 2.
NOTE:
* DIFFSENS: Refers to the SCSI bus signal
** DIFFSENSE: Refers to the pin name in HP7501.
2003/05/12
Ver. 0.0
2
HIMARK TECHNOLOGY INC.
HP7501
Ultra320 LVD/SE SCSI Terminator
BLOCK DIAGRAM
DIF_CAP
DIFFSENSE
ISO
MSTR/SLV
DIFFSENSE
CIRCUITRY
THERMAL
SHUTDOWN
CIRCUITRY
CONTROL
LOGIG
R1se
R2se
BANDGAP
REFERENCE
R1N
52 Ohm
2.85V
MUX
124 Ohm
52 Ohm
52 Ohm
124 Ohm
R9N
R1P
52 Ohm
1.25V
SE
GND
DRIVER
R9P
SE
GND
DRIVER
VREF
Figure 1. Block Diagram of HP7501
2003/05/12
Ver. 0.0
3
HIMARK TECHNOLOGY INC.
HP7501
Ultra320 LVD/SE SCSI Terminator
PIN DESCRIPTION ( for 36pin SSOP)
PIN
36
SYMBOL
TPWR
DESCRIPTION
2.7V to 5.25V power input pin. Connect to SCSI bus power line. A 4.7µF
capacitor and a 0.1µF high frequency capacitor are recommended between
TPWR and ground
Reference Voltage. Must be decoupled with a 4.7
u
F as shown in Figure 1.
Do not connect any signal to this pin.
Heat Sink Ground. Connect to large area PC board ground trace in order to
increase power dissipation.
1
2,3
8,9,10
26,27,28
4,6,11,13,15
22,24,29,31
5,7,12,14,16
23,25,30,32
17
VREF
NC
HGND
RxP
RxN
ISO
18
19
20
GND
MST/SLV
DIFFSENSE
21
33
34
35
DIF_CAP
SE
LVD
HVD
Termination lines. These lines switch to hard ground in SE mode and are the
positive lines for LVD mode. All lines are in high impedance when HVD is
detected.
Termination lines. These lines switch to the active lines in SE mode and are the
negative lines for LVD mode. All lines are in high impedance when HVD is
detected.
Isolation pin. This pin is used to shut down the terminator if the terminator is
not connected at the end of the bus. Connect the pin to ground will activate the
terminator in normal operation. The terminator will be disabled when the pin is
in high state. An internal pull-down resistor assures that the HP7501 will
operate as normal if the ISO pin is left floating.
Signal Ground.
Mode select pin. When pull high, master mode will enable the DIFFSEN drive
SCSI bus. The DIFFSENSE driver is off when this pin is connected to ground.
This signal will drive 1.3V to the SCSI bus during the Master mode in order to
detect which type of device is connected to the SCSI bus. On power up, the
HP7501 will try to deliver LVD level to the DIFFSENSE line. If only LVD SCSI
devices are on the bus, the DIFFSENSE signal will be successfully driven to
1.3V and the terminator will configure the system for LVD operation. If any SE
device is on the bus, it will present a grounding level to the DIFFSENSE line.
This will indicate HP7501 to configure into SE operation. HP7501 will be in shut
down mode if DIFFSENSE detects a high voltage level.
This pin should be connected to a 0.1uF capacitor to ground and 20K resistor
to SCSI bus DIFFSENS line for DIFFSEN filter.
Single ended. Indicates SE device is on the SCSI bus when this pin is active.
Low Voltage Differential. Indicates the terminator is in LVD operation.
High Voltage Differential. Indicates the HVD device is detected and terminator
is in shut down mode.
PIN DESCRIPTION ( for 28pin TSSOP)
PIN
27,28
SYMBOL
TPWR
DESCRIPTION
2.7V to 5.25V power input pin. Connect to SCSI bus power line. A 4.7µF
capacitor and a 0.1µF high frequency capacitor are recommended between
TPWR and ground.
Reference Voltage. Must be decoupled with a 4.7
u
F as shown in Figure 1.
Heat Sink Ground. Connect to large area PC board ground trace in order to
increase power dissipation.
Termination lines. These lines switch to hard ground in SE mode and are the
positive lines for LVD mode. All lines are in high impedance when HVD is
detected.
Termination lines. These lines switch to the active lines in SE mode and are the
negative lines for LVD mode. All lines are in high impedance when HVD is
detected.
Isolation pin. This pin is used to shut down the terminator if the terminator is
not connected at the end of the bus. Connect the pin to ground will activate the
terminator in normal operation. The terminator will be disabled when the pin is
in high state. An internal pull-down resistor assures that the HP7501 will
operate as normal if the ISO pin is left floating.
1
6,22
2,4,7,9,11
18,20,23,25
3,5,8,10,12
19,21,24,26
13
VREF
HGND
RxP
RxN
ISO
2003/05/12
Ver. 0.0
4
HIMARK TECHNOLOGY INC.
HP7501
Ultra320 LVD/SE SCSI Terminator
14
15
16
GND
MST/SLV
DIFFSENSE
Signal Ground.
Mode select pin. When pull high, master mode will enable the DIFFSEN drive
SCSI bus. The DIFFSENSE driver is off when this pin is connected to ground.
This signal will drive 1.3V to the SCSI bus during the Master mode in order to
detect which type of device is connected to the SCSI bus. On power up, the
HP7501 will try to deliver LVD level to the DIFFSENSE line. If only LVD SCSI
devices are on the bus, the DIFFSENSE signal will be successfully driven to
1.3V and the terminator will configure the system for LVD operation. If any SE
device is on the bus, it will present a grounding level to the DIFFSENSE line.
This will indicate HP7501 to configure into SE operation. HP7501 will be in shut
down mode if DIFFSENSE detects a high voltage level.
This pin should be connected to a 0.1uF capacitor to ground and 20K resistor
to SCSI bus DIFFSENS line for DIFFSEN filter.
17
DIF_CAP
RECOMMENDED OPERATING CONDITIONS
PARAMETER
Termpower Voltage (SE)
Termpower Voltage (LVD)
SYMBOL
Vtpwr
V
il
V
ih
Ta
MIN
4.0
2.7
TYP
MAX
5.25
5.25
UNITS
V
V
NOTES
Logic 0 (Low)
Logic 1 (High)
Operating Temperature
-0.3
2.0
0
+0.8
Vtpwr+0.3
70
V
V
℃
DC CHARACTERISTICS
PARAMETER
TPWR Current (SE)
TPWR Current (LVD)
Input Leakage Current
High
Input Leakage Current
Low
Output Current High
Vout = 2.4 V
Output Current Low
Vout = 0.4V
DIFFSEN Output Voltage
DIFFSEN Source Current
DIFFSEN Sink Current
DIFFSEN SE
Voltage Range
DIFFSEN LVD
Voltage Range
DIFFSEN HVD
Voltage Range
SYMBOL
Itpwr
Itpwr
Iih
MIN
TYP
15
25
MAX
UNITS
mA
mA
uA
NOTES
*1
0
1.0
0
4.0
1.2
5
20
-0.3
0.7
2.4
1.4
15
200
0.5
1.9
Vtpwr+0.3
Iil
Ioh
Iol
Vov
Isc
Isi
Vse
Vlvd
Vhvd
uA
mA
mA
V
mA
uA
V
V
V
2003/05/12
Ver. 0.0
5
HIMARK TECHNOLOGY INC.
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