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1 IMP5225
DATA COMMUNICATIONS
18-Line Plug and Play SCSI Terminator
The IMP5225 SCSI terminator is part of IMP's family of highperformance SCSI terminators, which are designed to deliver true UltraSCSI performance. The BiCMOS design offers superior performance over first generation linear passive and active techniques. 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/terminator approach. Products using the older regulator/resistor architecture have bandwidths which are dominated by the reference stabilization output capacitor and are therefore limited to 500kHz (see further discussion in the Functional Description section). The IMP architecture eliminates the output compensation capacitor required in linear regulator/ resistor designs. The IMP5225 architecture tolerates marginal system designs. A key improvement offered by the IMP5225 lies in its ability to insure reliable, error-free communications even in systems which do not adhere to recommended SCSI hardware design guidelines, such as the use of improper cable lengths and impedances. Frequently, this situation is not controlled by the peripheral or host designer. The IMP5225 has two disconnect pins for SCSI Plug and Play (PnP) applications. To enter the disconnect mode, the disconnect pins must be driven LOW thereby disconnecting the IMP5225 from the SCSI bus. Quiescent current is less than 150A when disabled. Reduced component count is inherent in the IMP5225 architecture. Traditional termination techniques require large stabilization and
Key Features
x SCSI Plug and Play -- Dual active LOW disconnect pins x Ultra-Fast response for Fast-20 SCSI x 35MHz channel bandwidth x Sleep-mode current less than 150A -- Disconnects terminator from lows x NO external compensation capacitors x Compatible with active negation drivers x Compatible with passive and active terminations x Approved for use with SCSI 1, 2, 3 and Ultra SCSI x Hot swap compatible x Pin-for-pin compatible with LX5225, LX5205 and UC5607
transient protection capacitors of up to 20F in value and size. The IMP5225 architecture does not require these components, allowing all the cost savings associated with inventory, board space, assembly, reliability, and component costs. The IMP5225 is a superior pin-for-pin replacement for the LX5225, LX5205, UC5607.
Block Diagrams
Term Power
VTERM
Current Biasing Circuit
24mA Current Limiting Circuit
DATA OUTPUT PIN DB (0)
2.85V
DISCONNECT 1 DISCONNECT 2
Enable Logic
-
1 of 18 Channels
+
0.4V VTERM
5225_01.eps
(c) 2000 IMP, Inc.
408-432-9100/www.impweb.com
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Pin Configuration
SOWB-28
DISCONNECT 1 T1 T2 T3 T4 T5 HEAT SINK / GND GND HEAT SINK / GND 1 2 3 4 5 6 7 8 9 IMP5225 28 DISCONNECT 2 27 T18 26 T17 25 T16 24 T15 23 T14 22 HEAT SINK / GND 21 HEAT SINK / GND 20 HEAT SINK / GND 19 T13 18 T12 17 T11 16 T10 15 NC
5225_02.eps
T6 10 T7 11 T8 12 T9 13 VTERM 14 DWP Package
Ordering Information
Part Number
IMP5225CDWP IMP5225CDWPT
Temperature Range
0C to 70C 0C to 70C
Package
28-pin Plastic SOWB Tape and Reel, 28-pin Plastic SOWB
5225_t01.at3
Absolute Maximum Ratings1
TermPwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . +7V Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . 0V to +7V Differential Voltage . . . . . . . . . . . . . . . . . . . . . 0V to 6.5V Operating Junction Temperature Plastic (DWP Package) . . . . . . . . . . . . . . . . 150C Storage Temperature Range . . . . . . . . . . . . . . -65C to 150C Lead Temperature (Soldering, 10 sec.) . . . . . . 300C 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
DWP Package: Thermal Resistance Junction-to-Leads, JL . . . . . . . . 18C/W Thermal Resistance Junction-to-Ambient, JA . . . . . . 40C/W Junction Temperature Calculation: TJ = TA + (PD x JA). The JA numbers are guidelines for the thermal performance of the device/pc-board system. All of the ambient airflow is assumed.
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(c) 2000 IMP, Inc.
IMP5IMP5225 1 1 1/51 1 2
Recommended Operating Conditions
Parameter
Termpwr Voltage Signal Line Voltage Disconnect Input Voltage Operating Junction Temperature Range - IMP5225C
Symbol
VTERM
Min
4.0 0 0 0
Typ
Max
5.5 5.0 VTERM 125
Units
V V V C
5225_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 TA = 25C. TermPwr = 4.75V. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.
Parameter
Output High Voltage TermPwr Supply Current
Symbol Conditions
VOUT ICC All data lines = Open All data lines = 0.2V DISCONNECT Pins < 0.8V
Min
2.65
Typ
2.85 10 424 50
Max
15 450 150 -24 -10 1
Units
V mA A mA A A MHz mA
5225_t03.eps
Output Current Disconnect Input Current Output Leakage Current Channel Bandwidth Termination Sink Current, per Channel
IOUT IIN IOL BW ISINK
VOUT = 0.5V DISCONNECT Pins = 0V DISCONNECT Pins < 0.8V, VO = 0.2V
-20
-22
35 VOUT = 4V 7
(c) 2000 IMP, Inc.
Data Communications
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Application Information
Figure 1. Receiving Waveform - 20MHz
Receiver DISCONNECT 1 IMP5225 DISCONNECT 2 1 Meter, AWG 28
Figure 2. Driving Waveform - 20MHz
Driver DISCONNECT 1 IMP5225 DISCONNECT 2
5225_03.eps
Figure 3.
Cable transmission theory suggests to optimize signal speed and quality, the termination should act both as an ideal voltage reference 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 resistors (typically 110) are a compromise. With coventional linear terminators as the line voltage increases the amount of current decreases linearly by the equation; Acting as a near ideal line terminator, the IMP5225 closely reproduces the optimum case when the device is enabled. To enable the device the DISC1 and DISC2 pins are pulled HIGH. During this mode of operation, quiescent current is 10mA, and the device will respond to line demands by delivering 24mA on assertion and by imposing 2.85V on deassertion. In order to disable the device, the DISC1 and DISC2 pins must be driven LOW. In the disable mode, the device is in a sleep state with quiescent current less than 150A. When disabled, all outputs are in a high impedance state. Sleep mode can be used for power conservation or to remove the terminator from the SCSI chain. An additional feature of the IMP5225 is its compatibility with active negation drivers.
(VREF - VLINE) = I.
R The IMP5225, with its unique new architecture, applies the maximum amount of current regardless of line voltage until the termination high threshold (2.85V) is reached.
Table 1. Power Up/ Power Down Function Table
DISCONNECT 1
H H L L Open
DISCONNECT 2
H L H L Open
Outputs
Disabled Enabled Enabled Disabled Disabled
Maximum Quiescent Current
15mA 15mA 15mA 150A 150A
5225_t04.eps
4
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(c) 2000 IMP, Inc.
IMP5IMP5225 1 1 1/51 1 2
Application Information
HOST
5V
4.7F
PERIPHERAL
TERM POWER
VTERM
4.7F
TERM POWER
VTERM
5V
DISCONNECT
~~~
IMP5225
ACK RST MSG
ACK RST MSG
IMP5225
SCSI CABLE
5225_04.eps
Figure 4. Application Schematic
(c) 2000 IMP, Inc.
Data Communications
DISCONNECT
5
DB (0) DB (1)
~~
DB (0) DB (1)
IMP5225 1
Package Dimensions
SOWB (28-Pin)
A
Inches Min Max SOWB (28-Pin)*
Millimeters Min Max
28
15
B
1 14
P
F
G
D
C SEATING PLANE K J
M
28-Pin (SOWB)DWP.eps
A 0.698 0.713 B 0.291 0.299 C 0.093 0.104 D 0.013 0.018 F 0.016 0.050 G 0.050 BSC J 0.009 0.013 K 0.004 0.012 M 0 8 P 0.394 0.419 * JEDEC Drawing MO-013AE
17.70 18.10 7.40 7.60 2.35 2.65 0.33 0.51 0.40 1.27 1.27 BSC 0.23 0.32 0.10 0.30 0 8 10.00 10.65
5225_t05.at3
IMP, Inc. Corporate Headquarters 2830 N. First Street San Jose, CA 95134-2071 Tel: 408-432-9100 Fax: 408-432-1085 e-mail: info@impinc.com http://www.impweb.com
The IMP logo is a registered trademark of IMP, Inc. All other company and product names are trademarks of their respective owners.
(c) 2000 IMP, Inc. Printed in USA Publication #: 7008 Revision: C Issue Date: 08/19/02 Type: Preliminary

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