IDTQS3389 Datasheet, PDF (1/5 Pages) Integrated Device Technology – QUICKSWITCH PRODUCTS LAST VALUE LATCH 20 ACTIVE BUS TERMINATORS

IDTQS3389
LAST VALUE LATCH 20 ACTIVE TERMINATORS (BUS HOLD)
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QUICKSWITCH^® PRODUCTS
LAST VALUE LATCH
20 ACTIVE BUS TERMINATORS
(BUS HOLD)
IDTQS3389
FEATURES:
• Active termination pulls bus pins to rails
• Holds last value of input signal
• Ideal replacement for resistive termination
• Ultra low 3µA DC quiescent current
• Bus-hold eliminates floating bus lines and reduces static
power consumption
• Low power QCMOS technology
• Operates over 2.7V to 5.5V Vcc range
• TTL-compatible input and output levels
• No added noise or ground bounce
• 20 independent terminator circuits
• Available in QSOP package
APPLICATIONS:
• Bus termination
• Extend data hold time
DESCRIPTION:
The QS3389 provides a set of 20 active termination circuits which pull data
bus signals to the voltage rails. This feature prevents bus signals from floating
in the threshold region of standard TTL I/O devices. The QS3389 can
replace resistor termination solutions which add DC power dissipation and
increase component count. Input clamp diodes help to reduce reflections
and undershoot in transmission line environments. Importantly, the termi-
nator circuits pull signals to whichever logic state the signal previously held
(high or low). For this reason, this device is also referred to as a last value
latch. This device is appropriate for data bus applications where interfacing
devices have CMOS inputs with low input currents. These terminators
provide sufficient drive to overcome leakage currents and drive corre-
sponding signals away from the TTL threshold region.
The QS3389 is characterized for operation at 0°C to +70°C.
FUNCTIONAL BLOCK DIAGRAM
T0
7KΩ
T19
7KΩ
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
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1
c
1999 Integrated Device Technology, Inc.
DECEMBER 1999
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