Ver: 0.1 Preliminary
Apr 03, 2003
TEL: 886-3-5788833
http://www.gmt.com.tw
1
G220
Global Mixed-mode Technology Inc.
Ultra320 Multi-mode LVD/SE SCSI Terminator
Features
Auto-selectable multi-mode Single-Ended
or LVD Termination
Meets SCSI-1, SCSI-2, SCSI-3 SPI Ultra
(Fast-20), Ultra 2(SPI-2 LVD), Ultra160 (SPI-3
LVD), and Ultra320 (SPI-4 LVD) standards
Supports active negation
3pF channel capacitance
2.9V to 5.5V operation
Thermal protection
Hot-Swap compatible
5% tolerance on SE and LVD termination
resistance
SE/LVD mode indicators
28 pin TSSOP package
Applications
Server and workstation
High-end PC
Industrial PC
Disk Array (RAID)
SCSI cable
General Description
The G220 Multi-mode LVD/SE SCSI terminator pro-
vides a smooth transition into the next generation of
the SCSI Parallel Interface (SPI-4). It automatically
senses the bus, via DIFFSENS, and switches the ter-
mination to either single-ended (SE) or low voltage
differential (LVD) SCSI, dependent on which type of
devices are connected to the bus. If the G220 detects
a HVD SCSI device, it switches to a high impedance
state. For a 16-bit Wide SCSI bus to be operational,
three G220 terminators are needed.
The Multi-mode terminator contains all functions re-
quired to terminate and auto detect and switch modes
for SCSI Parallel Interface (SPI) bus architectures. For
the SE termination, one regulator and nine precision
110ohm resistors are used. For the LVD termination,
the G220 integrates 18 regulated supplies with nine
precision resistor strings.
Ordering Information
ORDER
NUMBER
MARKING
TEMP.
RANGE
PACKAGE
G220D3X G220 0
C to +70C TSSOP-28L
Note: X Specify the packing type
U: Tape & Reel T: Tube
Pin Configuration
R1-
R1+
R2-
NC/ HS GND
R3+
R3-
R4+
R4-
R5+
R5-
DISCNCT
GND
TPWR
R9-
R9+
R8+
R8-
R7-
R6-
R6+
DIFFB
DIFFSENSE
M/S
TSSOP-28L
VREF
R2+
LVD
R7+
G220
1
2
3
4
28
27
26
25
5
6
7
8
9
10
11
12
13
14
24
23
22
21
20
19
18
17
16
15
SE
R1-
R1+
R2-
NC/ HS GND
R3+
R3-
R4+
R4-
R5+
R5-
DISCNCT
GND
TPWR
R9-
R9+
R8+
R8-
R7-
R6-
R6+
DIFFB
DIFFSENSE
M/S
TSSOP-28L
VREF
R2+
LVD
R7+
G220
1
2
3
4
28
27
26
25
5
6
7
8
9
10
11
12
13
14
24
23
22
21
20
19
18
17
16
15
SE
Ver: 0.1 Preliminary
Apr 03, 2003
TEL: 886-3-5788833
http://www.gmt.com.tw
2
G220
Global Mixed-mode Technology Inc.
Description
The G220 is used in multi-mode active termination
applications, where single ended (SE) and low voltage
differential (LVD) devices might coexist. The LVD ter-
mination section consists of 18 source/sink amplifiers
(VTOP, VBOT), biasing circuitry and nine precision
resistor strings (RTOP, RMID, RBOT). The SE termi-
nation section consists of a 2.85V source/sink regula-
tor with 9 precision 110ohm resistor. The DIFFSENSE
section consists of a 1.3V, 5mA driver and a sensing
circuit (Figure 1)
DIFFSENS is used to identify which types of SCSI
devices are present on the bus. If the voltage on
DIFFSENS is between 0-0.5V the bus is single-ended;
if it is between 0.7-1.9V the bus is LVD; and if it is
greater than 2.4V, the bus is HVD.
The G220 DIFFB pin monitors the DIFFSENS line to
determine the proper operating mode of the device.
HVD Isolation Mode The G220 identifies that there is
an HVD (high voltage differential) device on the SCSI
bus and isolates the termination pins from the bus.
When DISCNCT is pulled high, the termination pins
are isolated from the SCSI bus, and VREF is
grounded. 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.
To ensure proper operation, the TPWR pin should be
connected to the SCSI bus TERMPWR line. As with all
analog circuitry, the TERMPWR lines should be by-
passed locally. A 2.2F capacitor and a 0.01F high
frequency capacitor is recommended between TPWR
and ground and placed as close as possible to the
G220. The G220 should be placed as close as possi-
ble to the SCSI connector to minimize signal and
power trace length, thereby resulting in less input ca-
pacitance 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 G220 switches to the termi-
nation mode that is appropriate for the bus based on
the value of the DIFFSENS voltage. These modes are:
LVD mode LVD termination is provided by a precision
resistor string with two amplifiers. This configuration
yields a 105
differential and 150 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 regula-
tion. The terminating resistors maintain their 110
value.
To maintain the specified regulation, a 4.7F capacitor
is required between the VREF pin and ground of each
G220. A high frequency cap (0.1F ceramic recom-
mended) can also be placed on the VREF pin in ap-
plications that use fast rise/fall time drivers. A typical
SCSI bus configuration is shown in Figure2.
An internal pull down resistor assures that the G220
will be terminating the bus if the DISCNCT pin is left
floating.
DIFFSENS noise filtering
The G220 incorporates a internal digital filter to re-
move the noise signal on the DIFFSENS control line,
thereby eliminating erroneous switching between
modes. The external filter may be used in addition to
the internal digital filter.
Ver: 0.1 Preliminary
Apr 03, 2003
TEL: 886-3-5788833
http://www.gmt.com.tw
3
G220
Global Mixed-mode Technology Inc.
Block Diagram
(Figure 1)
DIFFB
DIFFSENSE
SE LVD
THERMAL
SHUTDOWN
CIRCUITRY
DISCNCT
CONTROL
LOGIC
VREF
DIFFSENSE
CIRCUITRY
REFERENCE
GENERATION
VREF
110 Ohms
110 Ohms
R1-
R9-
VTOP1
RTOP1
RMID1
RBOT1
R1+
R1-
R9-
R9+
R1-
R9-
SE
GND
DRIVER
VBOT1
R1+
R9+
+
_
+
_
X 9
X 9
RTOP9
RMID9
RBOT9
M/S
DIFFB
DIFFSENSE
SE LVD
THERMAL
SHUTDOWN
CIRCUITRY
DISCNCT
CONTROL
LOGIC
VREF
DIFFSENSE
CIRCUITRY
REFERENCE
GENERATION
VREF
110 Ohms
110 Ohms
R1-
R9-
VTOP1
RTOP1
RMID1
RBOT1
R1+
R1-
R9-
R9+
R1-
R9-
SE
GND
DRIVER
VBOT1
R1+
R9+
+
_
+
_
+
_
+
_
X 9
X 9
RTOP9
RMID9
RBOT9
M/S
Ver: 0.1 Preliminary
Apr 03, 2003
TEL: 886-3-5788833
http://www.gmt.com.tw
4
G220
Global Mixed-mode Technology Inc.
SCSI Bus Configuration
(Figure 2)
G220
G220
G220
G220
TPWR
M/S
DISCNCT
DIFFSENSE
CONTROL LINES (9)
DIFFSENS
TPWR
TERMPWR
20K
VREF DIFFB
0.1F
DIFFSENSE
DIFFB VREF
TERMPWR
TPWR
M/S
DISCNCT
DIFFB VREF
TPWR
DIFFB VREF
TPWR
DATA LINES (9)
VREF DIFFB
TPWR
VREF DIFFB
DATA LINES (9)
G220
G220
2.2F
2.2F
2.2F
2.2F
2.2F
2.2F
M/S
DISCNCT
M/S
DISCNCT
M/S
DISCNCT
M/S
DISCNCT
4.7F
4.7F
4.7F
4.7F
4.7F
4.7F
0.1F
20K
G220
G220
G220
G220
TPWR
M/S
DISCNCT
DIFFSENSE
CONTROL LINES (9)
DIFFSENS
TPWR
TERMPWR
20K
VREF DIFFB
0.1F
DIFFSENSE
DIFFB VREF
TERMPWR
TPWR
M/S
DISCNCT
DIFFB VREF
TPWR
DIFFB VREF
TPWR
DATA LINES (9)
VREF DIFFB
TPWR
VREF DIFFB
DATA LINES (9)
G220
G220
2.2F
2.2F
2.2F
2.2F
2.2F
2.2F
M/S
DISCNCT
M/S
DISCNCT
M/S
DISCNCT
M/S
DISCNCT
4.7F
4.7F
4.7F
4.7F
4.7F
4.7F
0.1F
20K
Ver: 0.1 Preliminary
Apr 03, 2003
TEL: 886-3-5788833
http://www.gmt.com.tw
5
G220
Global Mixed-mode Technology Inc.
Recommended Operating Conditions
PARAMETER SYMBOL MIN
TYP
MAX
UNITS
V
tpwr
(SE) 4.0
5
5.5
Termpower Voltage
V
tpwr
(LVD) 2.9
5
5.5
V
Logic 0
V
il
-0.3
+0.8 V
Logic 1
V
ih
2.0
V
tpwr
+0.3 V
Operating Temperature
T
amb
0
70 C
Electrical Characteristics
Unless otherwise specified, these specifications apply over the operating ambient temperature range of
0C
T
A
70C.
PARAMETER SYMBOL CONDITION MIN
TYP
MAX
UNITS
LVD Terminator Section
Differential Mode Termination Resistance
Rdm
100 105 110 Ohms
Common Mode Termination Resistance
Rcm
110
150
190
Ohms
Differential Mode Bias
Vdm
All lines Open
100
112
125
mV
Common Mode Bias
Vcm
1.125 1.25
1.375
V
Single Ended Terminator Section
Output Capacitance
Cout
Note
3
pF
SE Termination Resistance
Rse
Vline = 0-3.0 volts
104.5 110
115.5
Ohms
SE Voltage Reference
Vref
2.79 2.85
2.93
Volts
SE output Current
Iose
Vline = 0.2 volts
25.4
mA
Regulator Section
Line Regulation
LI
REG
1.0
2.5
%
Load Regulation
LO
REG
1.3
3.5
%
Current Limit
I
LIM
350
mA
Sink Current
I
SINK
200
mA
DC Section
SE mode (No Load)
4
Termpower Current
I
tpmr
LVD mode (No Load)
20
mA
Input Leakage High
I
ih
-1.0
A
Input Leakage Low
I
il
1.0
A
Output Current High
I
oh
V
out
= 2.4 volts; SE/LVD Pins only
-1.0
mA
Output Current Low
I
ol
V
out
=0.4 volts; SE/LVD Pins only
4.0
mA
DIFFSENS Section
DIFFSENS SE Operating Range
V
seor
-0.3
0.5
V
DIFFSENS LVD Operating Range
V
lvdor
0.7
1.9
V
DIFFSENS HVD Operating Range
V
hvdor
2.4
V
tpwr
+0.3 V
DIFFSENSE Driver Output Voltage
V
dso
M/S=1;
I
ds
= 0-5mA
1.2
1.4
V
DIFFSENSE Driver Source Current
I
dsh
M/S = 1; V
dso
=0V
5
15
mA
DIFFSENSE Driver Sink Current
I
dsl
M/S=1;
V
dso
=2.75V 20
200
A
Note: Guaranteed by Design.
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