GMT G218BR-S5, G218BR-S4, G218BR-D3, G218BT-S5, G218BT-S4 Datasheet
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Global Mixed-mode Technology Inc.
G218B
Ultra160 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) standards.
Supports active negation
3pF channel capacitance
Thermal protection
Hot-Swap compatible
5% tolerance on SE and LVD termination
resistance
28 and 36 pin SSOP package
28 Pin SSOP: Pin Compatible with DS2119
36 Pin SSOP: Pin Compatible with DS2118,
LX5241 and UCC5630
Applications
Server and workstation
High-end PC
Industrial PC
Disk Array (RAID)
SCSI cable
Pin Configuration
General Description
The G218B Multi-mode LVD/SE SCSI terminator provides a smooth transition into the next generation of
the SCSI Parallel Interface (SPI-3). It automatically
senses the bus, via DIFFSENS, and switches the termination to either single-ended (SE) or low voltage
differential (LVD) SCSI, dependent on which type of
devices are connected to the bus. If the G218B detects a HVD SCSI device, it switches to a high impedance state. For a 16-bit Wide SCSI bus to be operational, three G218B terminators are needed.
The Multi-mode terminator contains all functions required 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 G218B integrates 18 regulated supplies with nine
precision resistor strings.
VREF
VREF
VREF
NC/HS GND
NC/HS GND
NC/HS GND
DISCNCT
DISCNCT
DISCNCT
Ver 1.3
Jul 19, 2002
R1+
R1+
R1+
R1-
R1-
R1-
R2+
R2+
R2+
R2-
R2-
R2-
R3+
R3+
R3+
R3-
R3-
R3-
R4+
R4+
R4+
R4-
R4-
R4-
R5+
R5+
R5+
R5-
R5-
R5-
GND
GND
GND
G218B
G218B
G218B
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
10
10
10
11
11
11
12
12
12
13
13
13
14
14
14
28Pin SSOP/TSSOP
28Pin SSOP/TSSOP
28Pin SSOP/TSSOP
28
28
28
27
27
27
26
26
26
25
25
25
24
24
24
23
23
23
22
22
22
21
21
21
20
20
20
19
19
19
18
18
18
17
17
17
16
16
16
15
15
15
TPWR
TPWR
TPWR
TPWR
TPWR
TPWR
R9-
R9-
R9-
R9+
R9+
R9+
R8-
R8-
R8-
R8+
R8+
R8+
NC/HS GND
NC/HS GND
NC/HS GND
R7-
R7-
R7-
R7+
R7+
R7+
R6-
R6-
R6-
R6+
R6+
R6+
DIFFB
DIFFB
DIFFB
DIFFSENSE
DIFFSENSE
DIFFSENSE
M/S
M/S
M/S
1
G218B
G218B
36
36
1
1
VREF
VREF
2
2
NC
NC
3
3
NC
NC
4
4
R1+
R1+
5
5
R1-
R1-
6
6
R2+
R2+
R2-
R2-
7
7
HS/GND
HS/GND
HS/GND
HS/GND
HS/GND
HS/GND
DISCNCT
DISCNCT
R3+
R3+
R3-
R3-
R4+
R4+
R4-
R4-
R5+
R5+
R5-
R5-
GND
GND
10
10
11
11
12
12
13
13
14
14
15
15
17
17
18
18
16
16
8
8
9
9
36Pin SSOP
36Pin SSOP
TPWR
TPWR
35
35
HVD
HVD
34
34
LVD
LVD
33
33
SE
SE
32
32
R9-
R9-
31
31
R9+
R9+
30
30
R8-
R8-
29
29
R8+
R8+
HS/GND
HS/GND
28
28
27
27
HS/GND
HS/GND
26
26
HS/GND
HS/GND
25
25
R7-
R7-
24
24
R7+
R7+
23
23
R6-
R6-
22
22
R6+
R6+
DIFFB
DIFFB
21
21
20
20
DIFFSENSE
DIFFSENSE
19
19
M/S
M/S
TEL: 886-3-5788833
http://www.gmt.com.tw
Global Mixed-mode Technology Inc.
G218B
Ordering Information
PART NUMBER TEMP. RANGE PIN-PACKAGE FEATURE
G218BT-S4 0ºC-70ºC SSOP-28 pin / Tube DISCNCT does not disable VREF
G218BR-S4 0ºC-70ºC SSOP-28 pin / Tape & Reel DISCNCT does not disable VREF
G218BT-S5 0ºC-70ºC SSOP-36 pin / Tube DISCNCT does not disable VREF
G218BR-S5 0ºC-70ºC SSOP-36 pin / Tape & Reel DISCNCT does not disable VREF
G218BT-D3 0ºC-70ºC TSSOP-28 pin / Tube DISCNCT does not disable VREF
G218BR-D3 0ºC-70ºC TSSOP-28 pin / Tape & Reel DISCNCT does not disable VREF
Note:
DIFFSENSRefers to the SCSI bus signal.
DIFFSENSERefers to the G218B pin name and internal circuitry relating to differential sensing.
DIFFBRefers to the G218B pin name and internal circuitry relating to monitoring the DIFFSENS line.
Functional Description
The G218B is used in multi-mode active termination
applications, where single ended (SE) and low voltage
differential (LVD) devices might coexist. The LVD termination 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 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 G218B DIFFB pin monitors the DIFFSENS line to
determine the proper operating mode of the device;
this mode is indicated by the SE/LVD/HVD outputs.
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, the termination pins
are isolated from the SCSI bus, and the bus mode
indicators (SE/LVD/HVD) as well as VREF remains
active. During thermal shutdown, the termination pins
are isolated from the SCSI bus and VREF becomes
high impedance. 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 bypassed locally. A 2.2µF capacitor and a 0.01µF high
frequency capacitor is recommended between TPWR
The G218B identifies that there
and ground and placed as close as possible to the
G218B. The G218B should be placed as close as
possible to the SCSI connector to minimize signal and
power trace length, thereby resulting in less input capacitance 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 G218B switches to the termination mode that is appropriate for the bus based on
the value of the DIFFSENS voltage. These modes are:
LVD mode
resistor 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
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 110Ω
value.
To maintain the specified regulation, a 4.7µF capacitor
is required between the VREF pin and ground of each
G218B. A high frequency cap (0.1µF ceramic 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 Figure2.
An internal pull down resistor assures that the G218B
will be terminating the bus if the DISCNCT pin is left
floating.
LVD termination is provided by a precision
When the external driver for a given signal
Ver 1.3
Jul 19, 2002
2
TEL: 886-3-5788833
http://www.gmt.com.tw
Global Mixed-mode Technology Inc.
Block Diagram
VREF
VREF
(Figure 1)
M/ S
M/ S
DIFFSENSE
DIFFSENSE
CIRCUITRY
CIRCUITRY
DIFFSENSE
DIFFSENSE
(
(
36pin SSOP only
36pin SSOP only
LVD
LVD
SE
SE
VREF
VREF
HV D
HV D
110 Ohms
110 Ohms
)
)
SHUTDOWN
SHUTDOWN
DISCNCT
DISCNCT
THER MAL
THER MAL
CIRCUITRY
CIRCUITRY
CO NTROL
CO NTROL
LOGIC
LOGIC
R1-
R1-
G218B
DIFFB
DIFFB
REFERENCE
REFERENCE
GENERAT ION
GENERAT ION
R9-
R9-
110 Ohms
110 Ohms
VTOP1
VTOP1
+
+_+
_
_
RTO P9
X 9
X 9
RTO P1
RTO P1
R1-
R1-
RMI D1
RMI D1
R1+
R1+
RBO T1
RBO T1
+
+_+
_
_
VBOT1
VBOT1
RTO P9
RMI D9
RMI D9
RBO T9
RBO T9
R9-
R9-
R9+
R9+
R1-
R1-
R1+
R1+
R9-
R9-
R9+
R9+
Ver 1.3
Jul 19, 2002
X 9
X 9
3
SE
SE
GND
GND
DRIV ER
DRIV ER
TEL: 886-3-5788833
http://www.gmt.com.tw
Global Mixed-mode Technology Inc.
SCSI Bus Configuration
TERMPWR
TERMPWR
TERMPWR
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
TPWR
TPWR
TPWR
M/S
M/S
M/S
DISCNCT
DISCNCT
DISCNCT
VREF DIFFB
VREF DIFFB
VREF DIFFB
4.7µF
4.7µF
4.7µF
TPWR
TPWR
TPWR
M/S
M/S
M/S
DISCNCT
DISCNCT
DISCNCT
G218B
G218B
G218B
DIFFSENSE
DIFFSENSE
DIFFSENSE
(Figure 2)
0.1µF
0.1µF
0.1µF
20K
20K
20K
G218B
CONTROL LINES (9)
CONTROL LINES (9)
CONTROL LINES (9)
DIFFSENS
DIFFSENS
DIFFSENS
DATA LINES (9)
DATA LINES (9)
DATA LINES (9)
20K
20K
20K
G218B
G218B
G218B
DIFFSENSE
DIFFSENSE
DIFFSENSE
DIFFB VREF
DIFFB VREF
DIFFB VREF
0.1µF
0.1µF
0.1µF
TPWR
TPWR
TPWR
M/S
M/S
M/S
DISCNCT
DISCNCT
DISCNCT
TPWR
TPWR
TPWR
M/S
M/S
M/S
DISCNCT
DISCNCT
DISCNCT
4.7µF
4.7µF
4.7µF
TERMPWR
TERMPWR
TERMPWR
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
G218B G218B
G218B G218B
G218B G218B
DIFFB VREF
DIFFB VREF
DIFFB VREF
TPWR
TPWR
TPWR
M/S
M/S
M/S
DISCNCT
DISCNCT
DISCNCT
G218B
G218B
G218B
DIFFB VREF
DIFFB VREF
DIFFB VREF
4.7µF
4.7µF
4.7µF
4.7µF
4.7µF
4.7µF
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
VREF DIFFB
VREF DIFFB
VREF DIFFB
4.7µF
4.7µF
4.7µF
TPWR
TPWR
TPWR
M/S
M/S
M/S
DISCNCT
DISCNCT
DISCNCT
VREF DIFFB
VREF DIFFB
VREF DIFFB
4.7µF
4.7µF
4.7µF
G218B
G218B
G218B
DATA LINES (9)
DATA LINES (9)
DATA LINES (9)
Ver 1.3
Jul 19, 2002
4
TEL: 886-3-5788833
http://www.gmt.com.tw
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