IMP51 1 1/51 1 2
IMP52 8
D
ATA
C
OMMUNICATIONS
9-Line Plug and Play
SCSI Terminator
The 9-channel IMP5218 SCSI terminator is part of IMP's family of high-
performance SCSI terminators that deliver true UltraSCSI performance.
The BiCMOS design offers superior performance over first generation
linear regulator/resistor based terminators.
The IMP5218 has two disconnect pins for SCSI Plug and Play (PnP)
applications.
IMP's new architecture employs high-speed adaptive elements for each
channel, thereby providing the fastest response possible - typically
35MHz, which is 100 times faster than the older linear regulator termi-
nator approach. The bandwidth of terminators based on the older
regulator/resistor terminator architecture is limited to 500kHz since a
large output stabilization capacitor is required. The IMP architecture
eliminates the external output compensation capacitor and the need
for transient output capacitors while maintaining pin compatibility
with first generation designs. Reduced component count is inherent
with the IMP5218.
The IMP5218 architecture tolerates marginal system designs. A key
improvement offered by the IMP5218 lies in its ability to insure reliable,
error-free communications even in systems which do not adhere to rec-
ommended SCSI hardware design guidelines, such as improper cable
lengths and impedance. Frequently, this situation is not controlled by the
peripheral or host designer.
For portable and configurable peripherals, the IMP5218 can be placed in
a sleep mode with two disconnect signals. When disabled, the quiescent
current is typically 375µA, and the outputs are in a high impedance state.
Key Features
x
SCSI plug and play
— Dual disconnect pins
— Logic LOW disconnects lines
x
Hot swap compatible
x
Ultra-Fast response for Fast-20 SCSI applications
x
35MHz channel bandwidth
x
3.5V operation
x
Less than 3pF output capacitance
x
375µA disable-mode current
x
Thermally self limiting
x
No external compensation capacitors
x
Implements 8-bit or 16-bit (wide) applications
x
Compatible with active negation drivers
(60mA/channel)
x
Compatible with passive and active terminations
x
Approved for use with SCSI 1, 2, 3 and UltraSCSI
Block Diagrams
Term Power
Thermal
Limiting
Circuit
Current
Biasing
Circuit
24mA Current
Limiting Circuit
DATA OUTPUT
PIN DB (0)
2.85V
DISCONNECT 1
DISCONNECT 2
1 of 9 Channels
5218_01.eps
© 2000 IMP, Inc.
Data Communications
1
IMP51 1 1/51 1 2
IMP52 8
Pin Configuration
SOWB-16
TERM POWER
NC
D0
D1
D2
D3
D4
GND
1
2
3
4
5
6
7
8
DW Package
IMP5218
16 TERM POWER
15 DISCONNECT 1
14 DISCONNECT 2
13 D8
12 D7
11 D6
10 D5
9
GND
5218_02.eps
TSSOP-20
TERM POWER
NC
NC
D0
D1
D2
D3
D4
NC
1
2
3
4
5
6
7
8
9
IMP5218
20 TERM POWER
19 DISCONNECT 1
18 DISCONNECT 2
17 D8
16 D7
15 NC
14 D6
13 D5
12 NC
11 GND
PW Package
5218_02a.eps
GND 10
Ordering Information
Part Number
IMP5218CDW
IMP5218CDWT
IMP5218CPW
IMP5218CPWT
Temperature Range
0°C to 125°C
0°C to 125°C
0°C to 125°C
0°C to 125°C
Package
16-pin Plastic SOWB
Tape and Reel, 16-pin Plastic SOWB
20-pin Plastic TSSOP
Tape and Reel, 20-pin Plastic TSSOP
5218_t01.at3
Absolute Maximum Ratings
1
Continuous Termination Voltage . . . . . . . . . . . 10V
Continuous Output Voltage Range . . . . . . . . 0V to 5.5V
Continuous Disable Voltage Range . . . . . . . . 0V to 5.5V
Operating Junction Temperature . . . . . . . . . . 0°C to 125°C
Storage Temperature Range . . . . . . . . . . . . . . –65°C to 150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . 300°C
Note:
1. Exceeding these ratings could cause damage to the device. All
voltages are with respect to Ground. Currents are positive
into, negative out of the specified terminal.
Thermal Data
DW Package:
Thermal Resistance Junction-to-Ambient,
θ
JA
. . . . . . 95°C/W
PW Package:
Thermal Resistance Junction-to-Ambient,
θ
JA
. . . . . . 144°C/W
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the
device/pc-board system. All of the ambient airflow is assumed.
2
408-432-9100/www.impweb.com
© 2000 IMP, Inc.
IMP51 1 1/51 1 2
IMP52 8
Recommended Operating Conditions
2
Parameter
Termpwr Voltage
High Level Disable Input Voltage
Low Level Disable Input Voltage
Operating Junction Temperature Range
Symbol
V
TERM
V
IH
V
IL
Min
3.5
2
0
0
Typ
Max
5.5
V
TERM
0.8
125
Units
V
V
V
°C
5218_t02.eps
Note:
2. Recommended operating conditions indicate the range over which the device is functional.
Electrical Characteristics
Unless otherwise specified, these specifications apply at an ambient operating temperature of T
A
=
25°C. TermPwr = 4.75V. Low duty cycle
pulse testing techniques are used which maintain junction and case temperatures equal to the ambient temperature.
Parameter
Output High Voltage
TermPwr Supply Current
Symbol Conditions
V
OUT
I
CC
All data lines = Open
All data lines = 0.5V
DISCONNECT Pins 1, 2 = 0V
Min
2.65
Typ
2.85
6
215
375
Max
9
225
–24
Units
V
mA
mA
µA
mA
µA
µA
nA
pF
MHz
mA
5218_t03.eps
Output Current
Disable Input Current
Output Leakage Current
Capacitance in Disabled Mode
Channel Bandwidth
Termination Sink Current, per Channel
I
OUT
I
IN
I
OL
C
OUT
BW
I
SINK
V
OUT
= 0.5V
DISCONNECT Pins 1, 2 = 4.75V
DISCONNECT Pins 1, 2 = 0V
DISCONNECT Pins = 0V, V
O
= 0.5V
V
OUT
= 0V, Frequency = 1MHz
V
OUT
= 4V
–21
–23
90
–10
10
3
35
60
© 2000 IMP, Inc.
Data Communications
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IMP51 1 1/51 1 2
IMP52 8
Application Information
Figure 1. Receiving Waveform – 20MHz
Figure 2. Driving Waveform – 20MHz
Receiver
1 Meter, AWG 28
IMP5218
Driver
IMP5218
5218_03.eps
Figure 3.
IMP5218 Maximizes Line Current
Cable transmission theory suggests to optimize signal speed and
quality, the termination should act both as an ideal voltage refer-
ence when the line is released (deasserted) and as an ideal
current source when the line is active (asserted). Common active
terminators which consist of linear regulators in series with resis-
tors (typically 110Ω) are a compromise. With coventional linear
terminators as the line voltage increases the amount of current
decreases linearly by the equation;
device the Disconnect 1 and Disconnect 2 pins must be driven per
Table 1.
When enabled, quiescent current is 6mA and the device
will respond to line demands by delivering 24mA on assertion
and by imposing 2.85V on de-assertion.
Disable/Sleep Mode
Disable/Sleep mode can be used for power conservation or to
remove the terminator from the SCSI chain.
The IMP5218 is disabled when both disconnect pins are driven
logic LOW.
Disable mode places the device in a sleep state, where quiescent
current is typically 375µA. When disabled, all outputs are in a
high impedance state and each output has only 3pF of capaci-
tance.
An additional feature of the IMP5218 is its compatibility with
active negation drivers.
(
V
REF
−
V
LINE
)
=
I.
R
The IMP5218, with its unique new architecture, applies the maxi-
mum amount of current regardless of line voltage until the
termination high threshold (2.85V) is reached.
Acting as a near ideal line terminator, the IMP5218 closely repro-
duces the optimum case when the device is enabled. To enable the
4
408-432-9100/www.impweb.com
© 2000 IMP, Inc.
IMP51 1 1/51 1 2
IMP52 8
Application Information
Table 1. Power Up/ Power Down Function Table
DISCONNECT 1
H
H
L
L
Open
DISCONNECT 2
H
L
H
L
Open
Outputs
Enabled
Enabled
Enabled
Disabled/High Impedance
Enabled
Quiescent Current
6mA
6mA
6mA
375
µA
6mA
5218_t04.eps
Typical Characteristics
Figure 4. Receiving Waveform
3.5
Frequency = 1.03844MHz
3.0
2.5
3.0
2.5
3.5
Frequency = 1.00266MHz
Figure 5. Driving Waveform
Line Voltage (V)
2.0
1.5
1.0
0.5
GND
–0.5
Line Voltage (V)
Time (250ns/Div.)
2.0
1.5
1.0
0.5
GND
–0.5
5218_04.eps
Time (250ns/Div.)
5218_05.eps
Receiver
Figure 4
6 Meter, 92Ω
IMP5218
75C08
Driver
Figure 5
IMP5218
75C08
5218_06.eps
Figure 6. End-Driven Cable
© 2000 IMP, Inc.
Data Communications
5
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